6 System and Network Configuration</ti tle> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <meta http-equiv="Content-Language" content="EN"> <meta http-equiv="Content-Style-Type" content="text/css"> <meta http-equiv="Content-Script-Type" content="text/javascript"> <meta name="ro bots" content="all" scheme="http://www.robotstxt.org/"> <meta name="doctitle" content="Oracle® High Availability Architecture and Best Practices 10g Release 1 (10.1)"> <meta name="partno" content="B10726-01"> <meta name="docid" content="MAXAV"> <link rel="Start" href="../../index.htm" title="Home" type="text/html"> <link rel="Copyright" href="../../dcommon/html/cpyr.htm" title="Copyright" typ e="text/html"> <link rel="Stylesheet" href="../../dcommon/css/doccd.css" title="Default" type="text/css"> <link rel="Contents" href=" toc.htm" title="Contents" type="text/html"> <link rel="Index" href="index.htm" title="Index" type="text/html"> <link rel="Prev" href= "partpage3.htm" title="Previous" type="text/html"> <link rel="Next" href="configbp.htm" title="Next" type="text/html"> <link rel="alt ernate" href="../b10726.pdf" title="PDF version" type="application/pdf"> </head> <body> <div class="header"> <p><a name="top" id="top " href="#BEGIN">Skip Headers</a></p> <table summary="" cellspacing="0" cellpadding="0" width="100%"> <tr> <td align="left" valign="to p"><font color="#330099" face="Helvetica, Arial, sans-serif"><strong>Oracle® High Availability Architecture and Best Practices<br > 10<i>g</i> Release 1 (10.1)</strong><br> Part Number B10726-01</font></td> <td valign="bottom" align="right"> <table summary="" ce llspacing="0" cellpadding="0" width="270"> <tr> <td align="center" valign="top"><a href="../../index.htm"><img src="../../dcommon/gif s/prodicon.gif" alt="Go to Documentation Home" border="0"><br> <font size="-2">Home</font></a></td> <td align="center" valign="top">< a href="../../nav/portal_3.htm"><img src="../../dcommon/gifs/bookicon.gif" alt="Go to Book List" border="0"><br> <font size="-2">Book List</font></a></td> <td align="center" valign="top"><a href="toc.htm"><img src="../../dcommon/gifs/conticon.gif" alt="Go to Table o f Contents" border="0"><br> <font size="-2">Contents</font></a></td> <td align="center" valign="top"><a href="index.htm"><img src=".. /../dcommon/gifs/indxicon.gif" alt="Go to Index" border="0"><br> <font size="-2">Index</font></a></td> <td align="center" valign="top "><a href="../../mix$101/b12039/toc.htm"><img src="../../dcommon/gifs/mix.gif" alt="Go to Master Index" border="0"><br> <font size="- 2">Master Index</font></a></td> <td align="center" valign="top"><a href="../../dcommon/html/feedback.htm"><img src="../../dcommo n/gifs/feedback.gif" alt="Go to Feedback page" border="0"><br> <font size="-2">Feedback</font></a></td></tr></table></td></tr></table > <hr> <table summary="layout table" cellspacing="0" cellpadding="0" width="100%"> <tr> <td align="left" valign="top"> <table summary ="layout table" cellspacing="0" cellpadding="0" align="left" width="90"> <tr> <td align="center" valign="top"><a href="partpage3.htm" ><img src="../../dcommon/gifs/larrow.gif" alt="Go to previous page" border="0"><br> <font size="-2">Previous</font></a></td> <td alig n="center" valign="top"><a href="configbp.htm"><img src="../../dcommon/gifs/rarrow.gif" alt="Go to next page" border="0"><br> <font s ize="-2">Next</font></a></td></tr></table></td> <td align="right" valign="top"><a href="../b10726.pdf"><font size="-2">View PDF</font ></a></td></tr></table> <a name="BEGIN"></a></div> <div class="IND"> <a name="1010704"></a>  <h1 class="Title"><font face="Arial, Helvetica, sans-serif" color="#330099">6<br> <a name="MAXAV007">System and Network Configu ration</a></font></h1>  <a name="1011253"></a> <p class="BP">This chapter provides recommendations for configuring the subcomponents that make up the database server tier and the network. It includes the following sections:</p> <ul class="LB1"> <li class="LB1" type="disc"><a name="1006188"></a><a href="sysnet.htm#1006192">Overview of System Configuration Recommendations</a></li> <li class="LB1" type="disc"><a name="1011304"></a><a href="sysnet.htm#1011291">Recommendations for Configuring Storage</a></li> <li class="LB1" type="disc"><a name="1011309"></a><a href="sysnet.htm#1011292">Recommendations for Configuring Server Hardware</a></li> < li class="LB1" type="disc"><a name="1011314"></a><a href="sysnet.htm#1011294">Recommendations for Configuring Server Software</a></li > <li class="LB1" type="disc"><a name="1010935"></a><a href="sysnet.htm#1011296">Recommendations for Configuring the Network</a></li> </ul> <a name="1006192"></a>  <h2 class="H1"><font face="Arial, Helvetica, sans-serif" color="#330099">Overvie w of System Configuration Recommendations</font></h2>  <a name="1011299"></a> <p class="BP">The goal of configuring a highly available environment is to create a redundant, reliable system and database without sacrificing simplicity and performance. T his chapter includes recommendations for configuring the subcomponents of the database server tier.</p> <a name="1011326"></a> <p cl ass="BP">These principles apply to all of the subcomponent recommendations:</p> <ul class="LB1"> <li class="LB1" type="disc"><a name= "1011327"></a><strong class="Bold">Redundancy</strong>: Choose components and capabilities that are redundant to reduce the risk from failures</li> <li class="LB1" type="disc"><a name="1011328"></a><strong class="Bold">Consolidation</strong>: Consolidate components where appropriate to reduce the number of components that can fail</li> <li class="LB1" type="disc"><a name="1011329"></a><strong cla ss="Bold">Expansion</strong>: Plan for future growth</li> <li class="LB1" type="disc"><a name="1011335"></a><strong class="Bold">Mana geability</strong>: Choose components that are reliable and can be serviced online <p><a name="1011330"></a></p> <div align="center" > <table class="NoteAlso" border="0" width="80%" cellpadding="0" cellspacing="0" dir="ltr" summary="This is a layout table to format a note" title="This is a layout table to format a note"> <tr class="NoteAlso"> <td class="NoteAlso"><a name="1011333"></a><font face= "Arial, Helvetica, sans-serif"><strong class="NH"><strong class="Bold">See Also</strong>:</strong></font> <a name="1011334"></a> <p class="NB">Your vendors' HA architecture and best practices documentation and recommendations for hardware, operating system, and clu ster configurations</p></td></tr></table></div></li></ul> <a name="1011291"></a>  <h2 class="H1"><font face="A rial, Helvetica, sans-serif" color="#330099">Recommendations for Configuring Storage</font></h2>  <a name="1011337"></a > <p class="BP">Electronic data is one of the most important assets of any business. Storage arrays that house this data must protec t it and keep it accessible to ensure the success of the company. This section describes characteristics of a fault-tolerant storage subsystem that protects data while providing manageability and performance. The following storage recommendations for all architectur es are discussed in this section:</p> <ul class="LB1"> <li class="LB1" type="disc"><a name="1011338"></a><a href="sysnet.htm#1011346" >Ensure That All Hardware Components Are Fully Redundant and Fault-Tolerant</a></li> <li class="LB1" type="disc"><a name="1011407"></ a><a href="sysnet.htm#1011351">Use an Array That Can Be Serviced Online</a></li> <li class="LB1" type="disc"><a name="1011412"></a><a href="sysnet.htm#1012414">Mirror and Stripe for Protection and Performance</a></li> <li class="LB1" type="disc"><a name="1011417"></ a><a href="sysnet.htm#1011355">Load-Balance Across All Physical Interfaces</a></li> <li class="LB1" type="disc"><a name="1011422"></a ><a href="sysnet.htm#1011364">Create Independent Storage Areas</a></li> <li class="LB1" type="disc"><a name="1012585"></a><a href="sy snet.htm#1011509">Define ASM Disk and Failure Groups Properly</a></li> <li class="LB1" type="disc"><a name="1011446"></a><a href="sys net.htm#1011547">Use HARD-Compliant Storage for the Greatest Protection Against Data Corruption</a></li></ul> <a name="1012595"></a> <p class="BP">The following section pertains specifically to RAC environments:</p> <ul class="LB1"> <li class="LB1" type="disc"><a n ame="1012596"></a><a href="sysnet.htm#1012458">Storage Recommendation for RAC</a></li></ul> <a name="1011346"></a>  <h3 class="H2"><font face="Arial, Helvetica, sans-serif" color="#330099">Ensure That All Hardware Components Are Fully Redundan t and Fault-Tolerant</font></h3>  <a name="1011347"></a> <p class="BP">All hardware components of a storage array must be fully redundant, from physical interfaces to physical disks, including redundant power supplies and connectivity to the array its elf.</p> <a name="1011348"></a> <p class="BP">The storage array should contain one or more spare disks (often called hot spares). Wh en a physical disk starts to report errors to the monitoring infrastructure, or fails suddenly, the firmware should immediately resto re fault tolerance by mirroring the contents of the failed disk onto a spare disk.</p> <a name="1011349"></a> <p class="BP">Connecti vity to the storage array must be fully redundant (referred to as multipathing) so that the failure of any single component in the da ta path from any node to the shared disk array (such as controllers, interface cards, cables, and switches) is transparent and keeps the array fully accessible. This achieves addressing the same logical device through multiple physical paths. A host-based device dri ver reissues the I/O to one of the surviving physical interfaces.</p> <a name="1011350"></a> <p class="BP">If the storage array incl udes a write cache, then it must be protected to guard against memory board failures. The write cache should be protected by multiple battery backups to guard against a failure of all external power supplies. The cache must be able to survive either by using the bat tery backup long enough for the external power to return or until all the dirty blocks in cache are guaranteed to be fully flushed to a physical disk.</p> <a name="1011351"></a>  <h3 class="H2"><font face="Arial, Helvetica, sans-serif" color=" #330099">Use an Array That Can Be Serviced Online</font></h3>  <a name="1011352"></a> <p class="BP">If a physical comp onent fails, then the array must allow the failed device to be repaired or replaced without requiring the array to be shut down or ta ken offline. Also, the storage array must allow the firmware to be upgraded and patched without shutting down the storage array.</p> <a name="1012414"></a>  <h3 class="H2"><font face="Arial, Helvetica, sans-serif" color="#330099">Mirror and St ripe for Protection and Performance</font></h3>  <a name="1012415"></a> <p class="BP">Data should be mirrored to prote ct against disk and other component failures and should be striped over a large number of disks to achieve optimal performance. This method of storage configuration is known as Stripe and Mirror Everything (SAME). The SAME methodology provides a simple, efficient, a nd highly available storage configuration.</p> <a name="1012416"></a> <p class="BP">Oracle's automatic storage management (ASM) feat ure always evenly stripes data across all drives within a disk troup with the added benefit of automatically rebalancing files across new disks when disks are added, or across existing disks if disks are removed. In addition, ASM can provide redundancy protection to protect against component failures or enable mirroring to be provided by the underlying storage array.</p> <a name="1012417"></a> < div align="center"> <table class="NoteAlso" border="0" width="80%" cellpadding="0" cellspacing="0" dir="ltr" summary="This is a layou t table to format a note" title="This is a layout table to format a note"> <tr class="NoteAlso"> <td class="NoteAlso"><a name="101242 0"></a><font face="Arial, Helvetica, sans-serif"><strong class="NH">See Also:</strong></font> <a name="1012421"></a> <ul class="NL"> <li class="NL" type="disc"><a name="1012422"></a>"Optimal Storage Configuration Made Easy" at <code><a href="http://otn.oracle.com/d eploy/availability/pdf/oow2000_same.pdf">http://otn.oracle.com/deploy/availability/pdf/oow2000_same.pdf</a></code></li> <li class="NL " type="disc"><a name="1012423"></a>An internal Oracle study validated the assertions made in "Optimal Storage Configuration Made Eas y". The study can be found at <code><a href="http://otn.oracle.com/deploy/availability/pdf/SAME_HP_WP_112002.pdf">http://otn.oracle.c om/deploy/availability/pdf/SAME_HP_WP_112002.pdf</a></code></li> <li class="NL" type="disc"><a name="1012424"></a><em class="Italic"> <a class="olinkSRC ADMIN" href="../../server$101/b10739/toc.htm">Oracle Database Administrator's Guide</a></em> for more information about ASM</li></ul></td></tr></table></div> <a name="1011355"></a>  <h3 class="H2"><font face="Arial, Helvetic a, sans-serif" color="#330099">Load-Balance Across All Physical Interfaces</font></h3>  <a name="1011356"></a> <p clas s="BP">Load balancing of I/O operations across physical interfaces is usually provided by a software package that is installed on the host. The purpose of this load balancing software is to redirect I/O operations to a less busy physical interface if a single host b us adapter (HBA) is overloaded by the current workload.</p> <a name="1011364"></a>  <h3 class="H2"><font face= "Arial, Helvetica, sans-serif" color="#330099">Create Independent Storage Areas</font></h3>  <a name="1011402"></a> <p class="BP">Create separate, independent storage areas for software, active database files, and recovery-related files.</p> <a name=" 1011365"></a> <p class="BP">The following storage areas are needed:</p> <ul class="LB1"> <li class="LB1" type="disc"><a name="101136 6"></a>Software area: A location where software is installed and log and trace files are created</li> <li class="LB1" type="disc"><a name="1011367"></a>Database area: A location where active database files such as datafiles, control files, online redo logs, and chan ge tracking files used in incremental backups are stored</li> <li class="LB1" type="disc"><a name="1011368"></a>Flash recovery area: A location where recovery-related files are created, such as multiplexed copies of the current control file and online redo logs, arc hived redo logs, backup sets, and flashback log files</li></ul> <a name="1011369"></a> <p class="BP">The storage containing the data base area should be as physically distinct as possible from the flash recovery area. At a minimum, the database area and flash recove ry area should not share the same physical disk drives or controllers. This practice ensures that the failure of a component that pro vides access to a datafile in the database area does not also cause the loss of the backups or redo logs in the flash recovery area n eeded to recover that datafile.</p> <a name="1011370"></a> <p class="BP">Storage options are defined as follows:</p> <ul class="LB1" > <li class="LB1" type="disc"><a name="1011371"></a>Regular file system: A local file system that is not shared by any other system</ li> <li class="LB1" type="disc"><a name="1011372"></a>Cluster file system (CFS): A file system that is equally addressable and access ible by all nodes in a cluster (unlike a shared file system where access is funneled through a master node)</li> <li class="LB1" type ="disc"><a name="1011373"></a>Automatic storage management (ASM): A tool designed specifically for Oracle database files that integra tes the capabilities of a file system and a volume manager</li> <li class="LB1" type="disc"><a name="1011374"></a>Raw device or logic al volume: A piece of storage typically managed by a logical volume manager that does not contain a file system</li></ul> <a name="10 11512"></a> <p class="BP">The rest of this section includes these topics:</p> <ul class="LB1"> <li class="LB1" type="disc"><a name=" 1011513"></a><a href="sysnet.htm#1011375">Storage Recommendations for Specific HA Architectures</a></li> <li class="LB1" type="disc"> <a name="1011517"></a><a href="sysnet.htm#1011509">Define ASM Disk and Failure Groups Properly</a></li></ul> <a name="1011375"></a> < !--TOC=h3-"1011375"--> <h4 class="H3"><font face="Arial, Helvetica, sans-serif" color="#330099">Storage Recommendations for Specific HA Architectures</font></h4>  <a name="1011376"></a> <p class="BP">For the "Data Guard only" architecture and MAA, the primary site and secondary site should each contain their own identically configured storage areas.</p> <a name="1011378"></a> <p c lass="BP">For the "RAC only" architecture and MAA, follow these recommendations:</p> <ul class="LB1"> <li class="LB1" type="disc"><a name="1011379"></a>Software area should be installed on a regular file system local to each node in the RAC cluster. This configurati on permits Oracle patch upgrades and eliminates the software as a single point of failure.</li> <li class="LB1" type="disc"><a name=" 1011380"></a>Both the database area and the flash recovery area must be accessible to all nodes in the RAC cluster. <ul class="LD2"> <li class="LD2" type="CIRCLE"><a name="1011381"></a>If a cluster file system (CFS) is available on the target platform, then both th e database area and flash recovery area can be created on either CFS or ASM.</li> <li class="LD2" type="CIRCLE"><a name="1011382"></a >If a cluster file system (CFS) is unavailable on the target platform, then the database area can be created either on ASM or on raw devices (with the required volume manager), and the flash recovery area must be created on ASM.</li></ul></li></ul> <a name="1011323" ></a> <p class="BP"><a href="sysnet.htm#1011460">Table 6-1</a> summarizes the independent storage recommendations by architectu re.</p> <a name="1011457"></a> <h5 class="TTW"><a name="1011457"></a><a name="1011460"></a> <strong><font face="Arial, Helvetica, sa ns-serif"><em>Table 6-1 Independent Storage Recommendations for HA Architectures </em></font></strong></h5> <table summary="" c lass="HRuleFormalWide" border="1" frame="HSIDES" rules="ROWS" width="100%" cellpadding="3" cellspacing="0" dir="ltr" title=""> <thead > <tr class="Formal"> <th class="Formal" align="left" valign="bottom" scope="col"><a name="1011464"></a> <font face="Arial, Helvetica , sans-serif"><strong>Storage Area</strong></font></th> <th class="Formal" align="left" valign="bottom" scope="col"><a name="1011484" ></a> <font face="Arial, Helvetica, sans-serif"><strong>Non-RAC Database</strong></font></th> <th class="Formal" align="left" valign= "bottom" scope="col"><a name="1011486"></a> <font face="Arial, Helvetica, sans-serif"><strong>RAC Database (CFS Available)</strong></ font></th> <th class="Formal" align="left" valign="bottom" scope="col"><a name="1011466"></a> <font face="Arial, Helvetica, sans-seri f"><strong>RAC Database (CFS Not Available)</strong></font></th></tr></thead> <tbody> <tr class="Formal" align="left" valign="top"> < td class="Formal"><a name="1011468"></a> <p class="TB">Software area</p></td> <td class="Formal"><a name="1011488"></a> <p class="T B">Regular file system</p></td> <td class="Formal"><a name="1011490"></a> <p class="TB">Regular file system</p></td> <td class="Form al"><a name="1011470"></a> <p class="TB">Regular file system</p></td></tr> <tr class="Formal" align="left" valign="top"> <td class=" Formal"><a name="1011472"></a> <p class="TB">Database area</p></td> <td class="Formal"><a name="1011492"></a> <p class="TB">Regular file system or ASM</p></td> <td class="Formal"><a name="1011494"></a> <p class="TB">CFS or ASM</p></td> <td class="Formal"><a name= "1011474"></a> <p class="TB">Raw or ASM</p></td></tr> <tr class="Formal" align="left" valign="top"> <td class="Formal"><a name="1011 476"></a> <p class="TB">Flash recovery area</p></td> <td class="Formal"><a name="1011496"></a> <p class="TB">Regular file system or ASM</p></td> <td class="Formal"><a name="1011498"></a> <p class="TB">CFS or ASM</p></td> <td class="Formal"><a name="1011478"></a> <p class="TB">ASM</p></td></tr></tbody></table> <a name="1012436"></a> <div align="center"> <table class="NoteAlso" border="0" widt h="80%" cellpadding="0" cellspacing="0" dir="ltr" summary="This is a layout table to format a note" title="This is a layout table to format a note"> <tr class="NoteAlso"> <td class="NoteAlso"><a name="1012439"></a><font face="Arial, Helvetica, sans-serif"><strong cl ass="NH">See Also:</strong></font> <a name="1012440"></a> <ul class="NL"> <li class="NL" type="disc"><a name="1012441"></a><em class ="Italic"><a class="olinkSRC BRADV" href="../../server$101/b10734/toc.htm">Oracle Database Backup and Recovery Advanced User's Guide< /a></em> for details about moving an existing database into ASM</li> <li class="NL" type="disc"><a name="1012447"></a>Your platform-s pecific installation guide and <em class="Italic"><a class="olinkSRC RACIN" href="../../dcommon/html/noexist.htm">Oracle Real Applica tion Clusters Installation and Configuration Guide</a></em> for details about setting up disks for use with ASM</li></ul></td></tr></ table></div> <a name="1011509"></a>  <h3 class="H2"><font face="Arial, Helvetica, sans-serif" color="#330099"> Define ASM Disk and Failure Groups Properly</font></h3>  <a name="1012318"></a> <p class="BP">ASM uses a concept calle d failure groups to protect data against disk or component failures. When using failure groups, ASM optimizes file layout to reduce t he unavailability of data due to the failure of a shared resource. Failure groups define disks that share components, so that if one disk fails, then other disks sharing the component might also fail. An example of what might be defined as a failure group is a strin g of SCSI disks on the same SCSI controller. Failure groups are used to determine which ASM disks to use for storing redundant data. For example, if 2-way mirroring is specified for a file, then redundant copies of file extents will be stored in separate failure gro ups.</p> <a name="1012319"></a> <p class="BP">Failure groups are used with storage that does not provide its own redundancy capabili ty, such as disks that have not been configured according to RAID. The manner in which failure groups are defined for an ASM disk gro up is site-specific because the definition depends on the configuration of the storage and how it is connected to the database system s. ASM attempts to maintain three copies of its metadata, requiring a minimum of three failure groups for proper protection.</p> <a n ame="1012320"></a> <p class="BP">When using ASM with intelligent storage arrays, the storage array's protection features (such as ha rdware RAID-1 mirroring) are typically used instead of ASM's redundancy capabilities, which are implemented by using the <code>EXTERN AL REDUNDANCY</code> clause of the <code>CREATE DISKGROUP</code> statement. When using external redundancy, ASM failure groups are no t used, because disks in an external redundancy disk group are presumed to be highly available.</p> <a name="1012321"></a> <p class= "BP">Disks, as presented by the storage array to the operating system, should not be aggregated or subdivided by the array because it can hide the physical disk boundaries needed for proper data placement and protection. If, however, physical disk boundaries are alw ays hidden by the array, and if each logical device, as presented to the operating system, has the same size and performance characte ristics, then simply place each logical device in the same ASM disk group (with redundancy defined as <code>EXTERNAL REDUNDANCY</code >),and place the database and flash recovery areas in that one ASM disk group. An alternative approach is to create two disk groups, each concsisting of a single logical device, and place the database area in one disk group and the flash recovery in the other disk g roup. This method provides additional protection against disk group metadata failure and corruption.</p> <a name="1012322"></a> <p c lass="BP">For example, suppose a storage array takes eight physical disks of size 36GB and configures them in a RAID 0+1 manner for p erformance and protection, giving a total of 144GB of mirrored storage. Futhermore, this 144GB of storage is presented to the operati ng system as two 72GB logical devices with each logical device being striped and mirrored across all eight drives. When configuring A SM, place each 72GB logical device in the same ASM disk group, and place the database area and flash recovery areas on that disk grou p.</p> <a name="1012323"></a> <p class="BP">If the two logical devices have different performance characteristics,( for example, one corresponds to the inner half and the other to the outer half of the underlying physical drives) then the logical devices should be placed in separate disk groups. Because the outer portion of a disk has a higher transfer rate, the outer half disk group should be u sed for the database area; the inner half disk group should be used for the flash recovery area.</p> <a name="1012324"></a> <p class ="BP">If multiple, distinct storage arrays are used with a database under ASM control, then multiple options are available. One optio n is to create multiple ASM disk groups that do not share storage across multiple arrays and place the database and flash recovery ar eas in separate disk groups, thus physically separating the database area from the flash recovery area. Another option is to create a single disk group across arrays that consists of failure groups, where each failure group contains disks from just one array.These o ptions provide protection against the failure of an entire storage array.</p> <a name="1011587"></a> <div align="center"> <table cla ss="NoteAlso" border="0" width="80%" cellpadding="0" cellspacing="0" dir="ltr" summary="This is a layout table to format a note" titl e="This is a layout table to format a note"> <tr class="NoteAlso"> <td class="NoteAlso"><a name="1011590"></a><font face="Arial, Helv etica, sans-serif"><strong class="NH">See Also:</strong></font> <a name="1011591"></a> <p class="NB"><em class="Italic"><a class="ol inkSRC ADMIN" href="../../server$101/b10739/toc.htm">Oracle Database Administrator's Guide</a></em></p></td></tr></table></div> <a na me="1011547"></a>  <h3 class="H2"><font face="Arial, Helvetica, sans-serif" color="#330099">Use HARD-Compliant Storage for the Greatest Protection Against Data Corruption</font></h3>  <a name="1011548"></a> <p class="BP">The Har dware Assisted Resilient Data (HARD) initiative is a program designed to prevent data corruptions before they happen. Data corruption s are very rare, but when they do occur, they can have a catastrophic effect on business. Under the HARD initiative, Oracle's storage partners implement Oracle's data validation algorithms inside storage devices. This makes it possible to prevent corrupted data from being written to permanent storage. The goal of HARD is to eliminate a class of failures that the computer industry has so far been powerless to prevent. RAID has gained a wide following in the storage industry by ensuring the physical protection of data; HARD take s data protection to the next level by going beyond protecting physical data to protecting business data.</p> <a name="1011549"></a> <p class="BP">In order to prevent corruptions before they happen, Oracle tightly integrates with advanced storage devices to create a system that detects and eliminates corruptions before they happen. Oracle has worked with leading storage vendors to implement Orac le's data validation and checking algorithms in the storage devices themselves. The classes of data corruptions that Oracle addresses with HARD include:</p> <ul class="LB1"> <li class="LB1" type="disc"><a name="1011550"></a>Writes that physically and logically corru pt data file, control file and log file blocks</li> <li class="LB1" type="disc"><a name="1011551"></a>Writes of Oracle blocks to inco rrect locations</li> <li class="LB1" type="disc"><a name="1011552"></a>Erroneous writes to Oracle data by programs other than Oracle< /li> <li class="LB1" type="disc"><a name="1011553"></a>Writes of partial or incomplete blocks</li></ul> <a name="1011554"></a> <p cl ass="BP">End-to-end block validation is the technology employed by the operating system or storage subsystem to validate the Oracle d ata block contents. By validating Oracle data in the storage devices, corruptions will be detected and eliminated before they can be written to permanent storage. This goes beyond the current Oracle block validation features that do not detect a stray, lost, or corr upted write until the next physical read.</p> <a name="1011555"></a> <p class="BP">Oracle vendors are given the opportunity to imple ment validation checks based on a specification. A vendors' implementation may offer features specific to their storage technology. O racle maintains a Web site that will show a comparison of each vendor's solution by product and Oracle version. For the most recent i nformation, see <code><a href="http://otn.oracle.com/deploy/availability/htdocs/HARD.html">http://otn.oracle.com/deploy/availability/ htdocs/HARD.html</a></code>.</p> <a name="1011654"></a> <div align="center"> <table class="NoteAlso" border="0" width="80%" cellpadd ing="0" cellspacing="0" dir="ltr" summary="This is a layout table to format a note" title="This is a layout table to format a note"> <tr class="NoteAlso"> <td class="NoteAlso"><a name="1011657"></a><font face="Arial, Helvetica, sans-serif"><strong class="NH">See Als o:</strong></font> <a name="1011658"></a> <p class="NB"><a href="apphard.htm#634660">Appendix A, "Hardware Assisted Resilient D ata (HARD) Initiative"</a></p></td></tr></table></div> <a name="1012458"></a>  <h3 class="H2"><font face="Aria l, Helvetica, sans-serif" color="#330099">Storage Recommendation for RAC</font></h3>  <a name="1012601"></a> <p class= "BP">The following recommendation applies to the "RAC only" architecture and MAA:</p> <ul class="LB1"> <li class="LB1" type="disc"><a name="1012602"></a><a href="sysnet.htm#1012600">Protect the Oracle Cluster Registry and Voting Disk From Media Failure</a></li></ul> <a name="1012600"></a>  <h4 class="H3"><font face="Arial, Helvetica, sans-serif" color="#330099">Protect the Oracle Cluster Registry and Voting Disk From Media Failure</font></h4>  <a name="1012473"></a> <p class="BP">The share d volumes created for the OCR and the voting disk should be configured using RAID to protect against media failure. This requires the use of an external cluster volume manager, cluster file system, or storage hardware that provides RAID protection.</p> <a name="1012 479"></a> <div align="center"> <table class="NoteAlso" border="0" width="80%" cellpadding="0" cellspacing="0" dir="ltr" summary="Thi s is a layout table to format a note" title="This is a layout table to format a note"> <tr class="NoteAlso"> <td class="NoteAlso"><a name="1012482"></a><font face="Arial, Helvetica, sans-serif"><strong class="NH">See Also:</strong></font> <a name="1012483"></a> <p class="NB"><em class="Italic"><a class="olinkSRC RACIN" href="../../dcommon/html/noexist.htm">Oracle Real Application Clusters Instal lation and Configuration Guide</a></em></p></td></tr></table></div> <a name="1011292"></a>  <h2 class="H1"><fo nt face="Arial, Helvetica, sans-serif" color="#330099">Recommendations for Configuring Server Hardware</font></h2>  <a name="1011739"></a> <p class="BP">The main server hardware components are the nodes for the database and application server farm and the components within each node such as CPU, memory, interface boards (such as I/O and network), storage, and the cluster interconne ct in a RAC environment.</p> <a name="1011796"></a> <p class="BP">This section includes the following topics:</p> <ul class="LB1"> < li class="LB1" type="disc"><a name="1011797"></a><a href="sysnet.htm#1011740">Server Hardware Recommendations for All Architectures</ a></li> <li class="LB1" type="disc"><a name="1011802"></a><a href="sysnet.htm#1011749">Server Hardware Recommendations for RAC</a></l i> <li class="LB1" type="disc"><a name="1011807"></a><a href="sysnet.htm#1011757">Server Hardware Recommendations for Data Guard</a>< /li></ul> <a name="1011740"></a>  <h3 class="H2"><font face="Arial, Helvetica, sans-serif" color="#330099">Ser ver Hardware Recommendations for All Architectures</font></h3>  <a name="1011813"></a> <p class="BP">The following rec ommendations apply to all architectures:</p> <ul class="LB1"> <li class="LB1" type="disc"><a name="1011814"></a><a href="sysnet.htm#1 011741">Use Fewer, Faster, and Denser Components</a></li> <li class="LB1" type="disc"><a name="1011819"></a><a href="sysnet.htm#10117 43">Use Redundant Hardware Components</a></li> <li class="LB1" type="disc"><a name="1011824"></a><a href="sysnet.htm#1011745">Use Sys tems That Can Detect and Isolate Failures</a></li> <li class="LB1" type="disc"><a name="1011829"></a><a href="sysnet.htm#1011747">Pro tect the Boot Disk With a Backup Copy</a></li></ul> <a name="1011741"></a>  <h4 class="H3"><font face="Arial, Helvetica, sans-serif" color="#330099">Use Fewer, Faster, and Denser Components</font></h4>  <a name="1011742"></a> <p class="BP">Use fewer, faster CPUs instead of more, slower CPUs. Use fewer higher-density memory modules instead of more lower-densit y memory modules. This reduces the number of components that can fail while providing the same service level. This needs to be balanc ed with cost and redundancy.</p> <a name="1011743"></a>  <h4 class="H3"><font face="Arial, Helvetica, sans-ser if" color="#330099">Use Redundant Hardware Components</font></h4>  <a name="1011744"></a> <p class="BP">Using redundan t hardware components enables the system to fail over to the working component while taking the failed component offline. Choose comp onents (such as power supplies, cooling fans, and interface boards) that can be repaired or replaced while the system is running to p revent unscheduled outages caused by the repair of hardware failures.</p> <a name="1011745"></a>  <h4 class="H 3"><font face="Arial, Helvetica, sans-serif" color="#330099">Use Systems That Can Detect and Isolate Failures</font></h4>  <a name="1011780"></a> <p class="BP">Use systems that can automatically detect failures and provide alternate paths around subsy stems that have failed or isolate the subsystem. Choose a system that continues to run despite a component failure and automatically works around the failed component without incurring a full outage. For example, find a system that can use an alternate path for I/O requests if an adapter fails or can avoid a bad physical memory location if a memory board fails.</p> <a name="1011747"></a>  <h4 class="H3"><font face="Arial, Helvetica, sans-serif" color="#330099">Protect the Boot Disk With a Backup Copy</fo nt></h4>  <a name="1011748"></a> <p class="BP">Because mirroring does not protect against accidental removal of a file or most corruptions of the boot disk, an online copy of the boot disk should be maintained so that the system can be quickly reboote d using the same operating system image if a critical file is removed or corruption occurs on the primary boot image. Operating syste m vendors often provide a mechanism to easily maintain multiple boot images.</p> <a name="1011749"></a>  <h3 c lass="H2"><font face="Arial, Helvetica, sans-serif" color="#330099">Server Hardware Recommendations for RAC</font></h3>  <h4 class="H3"><font face="Arial, Helvetica, sans-serif" color="#330099">Use a Support ed Cluster System to Run RAC</font></h4>  <a name="1011752"></a> <p class="BP">RAC provides fast, automatic recovery f rom node and instance failures. Using a properly supported configuration is necessary for a successful RAC implementation. A supporte d hardware configuration may encompass server hardware, storage arrays, interconnect technology, and other hardware components.</p> < a name="1011755"></a>  <h4 class="H3"><font face="Arial, Helvetica, sans-serif" color="#330099">Choose the Pro per Cluster Interconnect</font></h4>  <a name="1012375"></a> <p class="BP">Select an interconnect that has redundancy, high speed, low latency, low host resource consumption, and the ability to balance loads across multiple available paths. In two-nod e configurations, it may be possible to use a direct-connect interconnect between the two nodes, but a switch should be used instead to provide a degree of isolation between the network interface cards of the two nodes in the cluster. If you plan to have more than t wo nodes in the future, then choose a switch-based interconnect solution instead of direct-connect to reduce the complexity of adding additional nodes in the future. If you have more than two nodes, then a switch-based interconnect is highly recommended and, in many cases, a requirement of the cluster solution being used.</p> <a name="1011757"></a>  <h3 class="H2"><font fac e="Arial, Helvetica, sans-serif" color="#330099">Server Hardware Recommendations for Data Guard</font></h3>  <a name="1 011758"></a> <p class="BP">The following recommendation applies to both the primary and secondary sites in "Data Guard only" and MAA environments.</p> <a name="1011766"></a>  <h4 class="H3"><font face="Arial, Helvetica, sans-serif" color="#33 0099">Use Identical Hardware for Every Machine at Both Sites</font></h4>  <a name="1011767"></a> <p class="BP">Using i dentical hardware for machines at both sites provides a symmetric environment that is easier to administer and maintain. Such a symme tric configuration mitigates failures or performance inconsistencies following a switchover or failover because of dissimilar hardwar e.</p> <a name="1011294"></a>  <h2 class="H1"><font face="Arial, Helvetica, sans-serif" color="#330099">Recomm endations for Configuring Server Software</font></h2>  <a name="1011870"></a> <p class="BP">The recommendations for se rversoftware apply to all nodes in a RAC environment and to both the primary and secondary sites in a Data Guard and MAA environment because they contain the identical configuration.</p> <a name="1011904"></a> <p class="BP">This section includes the following topic s:</p> <ul class="LB1"> <li class="LB1" type="disc"><a name="1011908"></a><a href="sysnet.htm#1011871">Server Software Recommendation s for All Architectures</a></li> <li class="LB1" type="disc"><a name="1011913"></a><a href="sysnet.htm#1011897">Server Software Recom mendations for RAC</a></li></ul> <a name="1011871"></a>  <h3 class="H2"><font face="Arial, Helvetica, sans-ser if" color="#330099">Server Software Recommendations for All Architectures</font></h3>  <a name="1011924"></a> <p class ="BP">The following recommendations apply to all architectures:</p> <ul class="LB1"> <li class="LB1" type="disc"><a name="1011925"></ a><a href="sysnet.htm#1012767">Use the Same OS Version, Patch Level, Single Patches, and Driver Versions</a></li> <li class="LB1" typ e="disc"><a name="1011934"></a><a href="sysnet.htm#1011874">Use an Operating System That is Fault-Tolerant to Hardware Failures</a></ li> <li class="LB1" type="disc"><a name="1011939"></a><a href="sysnet.htm#1011876">Configure Swap Partititions Appropriately</a></li> <li class="LB1" type="disc"><a name="1011944"></a><a href="sysnet.htm#1011880">Set Operating System Parameters to Enable Future Grow th</a></li> <li class="LB1" type="disc"><a name="1011949"></a><a href="sysnet.htm#1011882">Use Logging or Journal File Systems</a></l i> <li class="LB1" type="disc"><a name="1012765"></a><a href="sysnet.htm#1011884">Mirror Disks That Contain Oracle and Application So ftware</a></li></ul> <a name="1012767"></a>  <h4 class="H3"><font face="Arial, Helvetica, sans-serif" color="# 330099">Use the Same OS Version, Patch Level, Single Patches, and Driver Versions</font></h4>  <a name="1012769"></a> <p class="BP">Use the same operating system version, patch level, single patches, and driver versions on all machines. Consistency wi th operating system versions and patch levels reduces the likelihood of encountering incompatibilities or small inconsistencies betwe en the software on all machines. In an open standards environment, it is impractical for any vendor to test each and every piece of n ew software with every combination of software and hardware that has been previously released. Temporary differences can be tolerated when using RAC or Data Guard as individual systems or groups of systems are upgraded or patched one at a time to minimize scheduled outages, if the goal is that all machines will be upgraded to the same versions and patch levels.</p> <a name="1011874"></a>  <h4 class="H3"><font face="Arial, Helvetica, sans-serif" color="#330099">Use an Operating System That is Fault-Tolera nt to Hardware Failures</font></h4>  <a name="1011875"></a> <p class="BP">Use an operating system that, when coupled w ith the proper hardware, supports the ability to automatically detect failures and provide alternate paths around subsystems that hav e failed or isolate subsystems. Choose a system that can continue running if a component, such as a CPU or memory board, fails and au tomatically provides paths around failed components, such as an alternate path for I/O requests in the event of an adapter failure.</ p> <a name="1011876"></a>  <h4 class="H3"><font face="Arial, Helvetica, sans-serif" color="#330099">Configure Swap Partititions Appropriately</font></h4>  <a name="1011877"></a> <p class="BP">Mirror disks containing swap partiti ons so that if a disk that contains a swap partition fails, it will not result in an application or system failure.</p> <a name="1011 878"></a> <p class="BP">Use disk-based swap instead of RAM-based swap. It is always good practice to make all system memory availabl e for database and application use unless the amount available is sufficiently oversized to accommodate swap.</p> <a name="1011879">< /a> <p class="BP">Do not use TMPFS (a Solaris implementation that stores files in virtual memory rather than on disk) or other file systems that exclusively use virtual memory instead of disks for storage for the <code>/tmp</code> file system or other scratch file systems. This prevents runaway programs that write to <code>/tmp</code> from having the potential to hang the system by exhausting al l virtual memory.</p> <a name="1011880"></a>  <h4 class="H3"><font face="Arial, Helvetica, sans-serif" color=" #330099">Set Operating System Parameters to Enable Future Growth</font></h4>  <a name="1011881"></a> <p class="BP">An example on UNIX is setting shared memory and semaphore kernel parameters high enough to enable future growth, thus preventing an outa ge for reconfiguring the kernel and rebooting the system. Verify that using settings higher than required either presents no overhead or incurs such small overhead on large systems that the effect is negligible.</p> <a name="1011882"></a>  <h4 class="H3"><font face="Arial, Helvetica, sans-serif" color="#330099">Use Logging or Journal File Systems</font></h4>  <a name="1011883"></a> <p class="BP">Journal file systems and logging reduce or eliminate the number of file system checks required following a system reboot, thereby facilitating faster restarting of the system.</p> <a name="1011884"></a>  < h4 class="H3"><font face="Arial, Helvetica, sans-serif" color="#330099">Mirror Disks That Contain Oracle and Application Software</fo nt></h4>  <a name="1011885"></a> <p class="BP">As with server hardware and software, the recommendations for Oracle so ftware apply to both the primary and secondary sites because they contain identical configurations. Mirror disks containing Oracle an d application software to prevent a disk failure from causing an unscheduled outage.</p> <a name="1011897"></a>  <a name="1011923"></a> <p class="BP">The following recommendations apply to a "RAC only" environment:</p> <ul class="LB1"> <li class="LB1" type="disc"><a name="1012628"></a><a href="sysnet.htm#1011898">Use Supported Clustering Software</a></li> <li class= "LB1" type="disc"><a name="1012633"></a><a href="sysnet.htm#1012626">Use Network Time Protocol (NTP) On All Cluster Nodes</a></li></u l> <a name="1011898"></a>  <h4 class="H3"><font face="Arial, Helvetica, sans-serif" color="#330099">Use Suppor ted Clustering Software</font></h4>  <a name="1011899"></a> <p class="BP">RAC provides fast, automatic recovery from n ode and instance failures. Using a properly supported configuration is a key component of success. A supported software configuration encompasses operating system versions and patch levels, clustering software versions, which possibly includes Oracle-supplied cluste r software. On some platforms (such as Solaris, Linux, and Windows), Oracle supplies cluster software required for use with RAC.</p> <a name="1012664"></a> <div align="center"> <table class="NoteAlso" border="0" width="80%" cellpadding="0" cellspacing="0" dir="ltr" summary="This is a layout table to format a note" title="This is a layout table to format a note"> <tr class="NoteAlso"> <td class=" NoteAlso"><a name="1012667"></a><font face="Arial, Helvetica, sans-serif"><strong class="NH">See Also:</strong></font> <a name="10126 68"></a> <p class="NB"><em class="Italic"><a class="olinkSRC RACIN" href="../../dcommon/html/noexist.htm">Oracle Real Application Cl usters Installation and Configuration Guide</a></em></p></td></tr></table></div> <a name="1012626"></a>  <h4 c lass="H3"><font face="Arial, Helvetica, sans-serif" color="#330099">Use Network Time Protocol (NTP) On All Cluster Nodes</font></h4>  <a name="1012627"></a> <p class="BP">Use NTP to synchronize the clocks on all nodes in the cluster to facilitate anal ysis of tracing information based on timestamps.</p> <a name="1011296"></a>  <h2 class="H1"><font face="Arial, Helvetica, sans-serif" color="#330099">Recommendations for Configuring the Network</font></h2>  <a name="1012077"></a> <p class="BP">This section includes the following topics:</p> <ul class="LB1"> <li class="LB1" type="disc"><a name="1012078"></a><a href="sysnet.htm#1011977">Network Configuration Best Practices for All Architectures</a></li> <li class="LB1" type="disc"><a name="1 012083"></a><a href="sysnet.htm#1012000">Network Configuration Best Practices for RAC</a></li> <li class="LB1" type="disc"><a name="1 012088"></a><a href="sysnet.htm#1012046">Network Configuration Best Practices for Data Guard</a></li></ul> <a name="1011977"></a> <!- -TOC=h2-"1011977"--> <h3 class="H2"><font face="Arial, Helvetica, sans-serif" color="#330099">Network Configuration Best Practices fo r All Architectures</font></h3>  <a name="1012093"></a> <p class="BP">The following recommendations apply to all archi tectures:</p> <ul class="LB1"> <li class="LB1" type="disc"><a name="1012094"></a><a href="sysnet.htm#1011978">Ensure That All Network Components Are Redundant</a></li> <li class="LB1" type="disc"><a name="1012099"></a><a href="sysnet.htm#1011996">Use Load Balancers to Distribute Incoming Requests</a></li></ul> <a name="1011978"></a>  <h4 class="H3"><font face="Arial, Helvet ica, sans-serif" color="#330099">Ensure That All Network Components Are Redundant</font></h4>  <a name="1011979"></a> <p class="BP"><a href="sysnet.htm#1012115">Table 6-2</a> describes the necessary redundant network components that are illustrat ed in <a href="sysnet.htm#1011994">Figure 6-1</a>.</p> <a name="1012112"></a> <h5 class="TTW"><a name="1012112"></a><a name="10 12115"></a> <strong><font face="Arial, Helvetica, sans-serif"><em>Table 6-2 Redundant Network Components </em></font></strong>< /h5> <table summary="" class="HRuleFormalWide" border="1" frame="HSIDES" rules="ROWS" width="100%" cellpadding="3" cellspacing="0" di r="ltr" title=""> <thead> <tr class="Formal"> <th class="Formal" align="left" valign="bottom" scope="col"><a name="1012119"></a> <fon t face="Arial, Helvetica, sans-serif"><strong>Component</strong></font></th> <th class="Formal" align="left" valign="bottom" scope="c ol"><a name="1012121"></a> <font face="Arial, Helvetica, sans-serif"><strong>Fault Tolerance</strong></font></th></tr></thead> <tbody > <tr class="Formal" align="left" valign="top"> <td class="Formal"><a name="1012142"></a> <p class="TB">Exterior connectivity (inclu ding remote IT staff)</p></td> <td class="Formal"><a name="1012144"></a> <p class="TB">Multiple internet service providers (ISP) ens ure that an ISP failure does not make your site unavailable. <a name="1012149"></a></p> <p class="TB">Note: The cables should not be housed within the same trunk into your facility. Otherwise, a saw or shovel can cut connections to multiple ISPs simultaneously.</p>< /td></tr> <tr class="Formal" align="left" valign="top"> <td class="Formal"><a name="1012146"></a> <p class="TB">WAN traffic manager< /p></td> <td class="Formal"><a name="1012148"></a> <p class="TB">Use a primary and a backup WAN traffic manager. (Not used with "Dat abase only" or "RAC only" environments) Environments using Data Guard contain a primary and a backup WAN traffic manager at each site .</p></td></tr> <tr class="Formal" align="left" valign="top"> <td class="Formal"><a name="1012123"></a> <p class="TB">Application lo ad balancer</p></td> <td class="Formal"><a name="1012125"></a> <p class="TB">Implement redundant application load balancers for dire cting client requests to the application server tier. The secondary load balancer should be identically configured with a heartbeat t o the primary load balancer. If the primary load balancer fails, then the secondary load balancer initiates a takeover function.</p>< /td></tr> <tr class="Formal" align="left" valign="top"> <td class="Formal"><a name="1012127"></a> <p class="TB">Firewall</p></td> <t d class="Formal"><a name="1012129"></a> <p class="TB">Implement redundant firewalls and load-balance across the pair. Because the co nnections through a firewall tend to be longer (socket connections versus HTTP), the load-balanceing decision needs to be made when t he session is initiated and maintained during the session. Check with your firewall vendor for available functionality.</p></td></tr> <tr class="Formal" align="left" valign="top"> <td class="Formal"><a name="1012131"></a> <p class="TB">Middle-tier application serve r</p></td> <td class="Formal"><a name="1012133"></a> <p class="TB">Implement application server farms. This provides fault tolerance and scalability.</p></td></tr></tbody></table> <a name="1011993"></a> <p class="BP"><a href="sysnet.htm#1011994">Figure 6-1</a > depicts a single site in an MAA environment, emphasizing the redundant network components.</p> <a name="1011994"></a> <h4 class="F TW"><font face="Arial, Helvetica, sans-serif"><em>Figure 6-1 Network Configuration</em></font></h4> <a name="1012153"><img src="maxav 010.gif" alt="Text description of maxav010.gif follows"></a> <p><a href="img_text/maxav010.htm">Text description of the illustration maxav010.gif</a></p> <a name="1011996"></a>  <h4 class="H3"><font face="Arial, Helvetica, sans-serif" color=" #330099">Use Load Balancers to Distribute Incoming Requests</font></h4>  <a name="1011997"></a> <p class="BP">Applicat ion layer load balancers sit logically in front of the application server farm and publish to the outside world a single IP address f or the service running on a group of application servers. All requests are initially handled by the load balancer, which then distrib utes them to a server within the application server farm. End users only need to address their requests to the published IP address; the load balancer determines which server should handle the request.</p> <a name="1011998"></a> <p class="BP">If one of the middle-t ier application servers cannot process a request, the load balancers route all subsequent requests to functioning servers. The load b alancers should be redundant to avoid being a single point of failure because all client requests pass through a single hardware-base d load balancer. Because failure of that piece of hardware is detrimental to the entire site, a backup load balancer is configured th at has a heartbeat with the primary load balancer. With two load balancers, one is configured as standby and becomes active only if t he primary load balancer becomes unavailable.</p> <a name="1012000"></a>  <h3 class="H2"><font face="Arial, He lvetica, sans-serif" color="#330099">Network Configuration Best Practices for RAC</font></h3>  <a name="1012177"></a> <p class="BP">This recommendation applies to RAC environments.</p> <a name="1012517"></a>  <h4 class="H3"><fon t face="Arial, Helvetica, sans-serif" color="#330099">Classify Network Interfaces Using the Oracle Interface Configuration Tool</font ></h4>  <a name="1012518"></a> <p class="BP">Use the Oracle Interface Configuration (OIFCFG) tool to classify network interfaces as public, cluster interconnect, or storage so that RAC properly selects a network interface for internode network traffic .</p> <a name="1012519"></a> <div align="center"> <table class="NoteAlso" border="0" width="80%" cellpadding="0" cellspacing="0" dir ="ltr" summary="This is a layout table to format a note" title="This is a layout table to format a note"> <tr class="NoteAlso"> <td c lass="NoteAlso"><a name="1012522"></a><font face="Arial, Helvetica, sans-serif"><strong class="NH">See Also:</strong></font> <a name= "1012523"></a> <p class="NB"><em class="Italic"><a class="olinkSRC RACAD" href="../../rac$101/b10765/toc.htm">Oracle Real Applicatio n Clusters Administrator's Guide</a></em></p></td></tr></table></div> <a name="1012046"></a>  <h3 class="H2">< font face="Arial, Helvetica, sans-serif" color="#330099">Network Configuration Best Practices for Data Guard</font></h3>  <h4 class="H3"><font face="Arial, Helvetica, sans-serif" color="#330099">Configure System TCP Parameters Appropriately</font></h4>  <a name="1012535"></a> <p class="BP">Configure system TCP parameters that control the sending and receiving buffer sizes so that the bandwidth between sites can be fully utilized for log transport serv ices. The proper buffer size is often governed by the bandwidth delay product (BDP) formula, particularly when using a high-speed, hi gh-latency network.</p> <a name="1012541"></a> <div align="center"> <table class="NoteAlso" border="0" width="80%" cellpadding="0" c ellspacing="0" dir="ltr" summary="This is a layout table to format a note" title="This is a layout table to format a note"> <tr class ="NoteAlso"> <td class="NoteAlso"><a name="1012548"></a><font face="Arial, Helvetica, sans-serif"><strong class="NH">See Also:</stron g></font> <a name="1012549"></a> <ul class="NL"> <li class="NL" type="disc"><a name="1012550"></a><a href="configbp.htm#1007027">"Co nfiguration Best Practices for Data Guard"</a><a href="configbp.htm#1007027"></a></li> <li class="NL" type="disc"><a name="1012557">< /a>Your operating system documentation for details about changing TCP parameters that contorl the sending and receiving buffer sizes< /li></ul></td></tr></table></div> <a name="1012047"></a>  <h4 class="H3"><font face="Arial, Helvetica, sans-se rif" color="#330099">Use WAN Traffic Managers to Provide Site Failover Capabilities</font></h4>  <a name="1012048"></a> <p class="BP">WAN traffic managers provide the initial access to the services located at the primary site. These managers are imple mented at the primary and secondary sites to provide site failover capabilities when the primary site becomes completely unavailable. Geographically separating the WAN traffic managers on separate networks reduces the impact of network failures or a natural disaster that causes the primary site to become unavailable.</p> <a name="1012607"></a> <div align="center"> <table class="NoteAlso" border= "0" width="80%" cellpadding="0" cellspacing="0" dir="ltr" summary="This is a layout table to format a note" title="This is a layout t able to format a note"> <tr class="NoteAlso"> <td class="NoteAlso"><a name="1012610"></a><font face="Arial, Helvetica, sans-serif"><s trong class="NH">See Also:</strong></font> <a name="1012611"></a> <p class="NB"><a href="recover.htm#1006233">"Complete or Partial S ite Failover"</a><a href="recover.htm#1006233"></a></p></td></tr></table></div></div> <div class="footer"> <hr> <table summary="" cel lspacing="0" cellpadding="0" width="100%"> <tr> <td style="width: 33%;" align="left"> <table summary="layout table" cellspacing="0" c ellpadding="0" align="left" width="90"> <tr> <td align="center" valign="top"><a href="partpage3.htm"><img src="../../dcommon/gifs/lar row.gif" alt="Go to previous page" border="0"><br> <font size="-2">Previous</font></a></td> <td align="center" valign="top"><a href=" configbp.htm"><img src="../../dcommon/gifs/rarrow.gif" alt="Go to next page" border="0"><br> <font size="-2">Next</font></a></td></tr ></table></td> <td style="width: 34%;" align="center"><img src="../../dcommon/gifs/oracle.gif" alt="Oracle"><br> <a href="../../dcomm on/html/cpyr.htm"><font size="-2">Copyright © 2003 Oracle Corporation</font></a><br> <font size="-2">All Rights Reserved.</font> </td> <td style="width: 33%;" align="right"> <table summary="" cellspacing="0" cellpadding="0" width="270"> <tr> <td align="center" v align="top"><a href="../../index.htm"><img src="../../dcommon/gifs/prodicon.gif" alt="Go to Documentation Home" border="0"><br> <font size="-2">Home</font></a></td> <td align="center" valign="top"><a href="../../nav/portal_3.htm"><img src="../../dcommon/gifs/bookico n.gif" alt="Go to Book List" border="0"><br> <font size="-2">Book List</font></a></td> <td align="center" valign="top"><a href="toc.h tm"><img src="../../dcommon/gifs/conticon.gif" alt="Go to Table of Contents" border="0"><br> <font size="-2">Contents</font></a></td> <td align="center" valign="top"><a href="index.htm"><img src="../../dcommon/gifs/indxicon.gif" alt="Go to Index" border="0"><br> <fo nt size="-2">Index</font></a></td> <td align="center" valign="top"><a href="../../mix$101/b12039/toc.htm"><img src="../../dcommon/gif s/mix.gif" alt="Go to Master Index" border="0"><br> <font size="-2">Master Index</font></a></td> <td align="center" valign="top" ><a href="../../dcommon/html/feedback.htm"><img src="../../dcommon/gifs/feedback.gif" alt="Go to Feedback page" border="0"><br> <font size="-2">Feedback</font></a></td></tr></table></td></tr></table></div> </body> </html>