SAP Solutions on VMware Best Practices Guide
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7. High Availability<br />
© 2011 <strong>VMware</strong>, Inc. All rights reserved.<br />
Page 13 of 32<br />
<str<strong>on</strong>g>SAP</str<strong>on</strong>g> <str<strong>on</strong>g>Soluti<strong>on</strong>s</str<strong>on</strong>g> <strong>on</strong> <strong>VMware</strong><br />
<strong>Best</strong> <strong>Practices</strong> <strong>Guide</strong><br />
The <strong>VMware</strong> Fault Tolerance (FT) and <strong>VMware</strong> High Availability (HA) features together can provide high<br />
availability opti<strong>on</strong>s for <str<strong>on</strong>g>SAP</str<strong>on</strong>g> single points of failure in the virtualized envir<strong>on</strong>ment.<br />
<strong>VMware</strong> FT protects a virtual machine by maintaining a sec<strong>on</strong>d virtual machine that runs in lockstep with<br />
the primary virtual machine. If the primary virtual machine goes down, the sec<strong>on</strong>dary machine takes over<br />
with no downtime. Currently, <strong>VMware</strong> FT supports <strong>on</strong>ly single-CPU virtual machines and is a viable<br />
soluti<strong>on</strong> for lightweight comp<strong>on</strong>ents of the <str<strong>on</strong>g>SAP</str<strong>on</strong>g> architecture such as Central Services. When deploying<br />
<str<strong>on</strong>g>SAP</str<strong>on</strong>g> Central Services standal<strong>on</strong>e in a virtual machine, note the following:<br />
Linux-based guest OS is supported by <str<strong>on</strong>g>SAP</str<strong>on</strong>g> and there are no caveats.<br />
For Windows-based guest OS, see <str<strong>on</strong>g>SAP</str<strong>on</strong>g> note 1609304, Installing a standal<strong>on</strong>e ASCS instance. To<br />
obtain support <strong>on</strong> Windows for a standal<strong>on</strong>e Central Services deployment in a virtual machine follow<br />
these guidelines:<br />
o Use a sapinst that allows installati<strong>on</strong> of standal<strong>on</strong>e Central Services (available from NetWeaver<br />
7.3, but also possible with some earlier versi<strong>on</strong>s).<br />
o Take care of RFC destinati<strong>on</strong>s that point to the virtual hostname of the Central Services by<br />
maintaining RFC group destinati<strong>on</strong>s or implementing a standal<strong>on</strong>e gateway.<br />
o In case of an upgrade, choose the correct upgrade tools (if you need advice, open a <str<strong>on</strong>g>SAP</str<strong>on</strong>g><br />
message under support comp<strong>on</strong>ent BC-UPG).<br />
o For clarificati<strong>on</strong>, open a <str<strong>on</strong>g>SAP</str<strong>on</strong>g> ticket under support comp<strong>on</strong>ent BC-OP-NT-ESX before proceeding<br />
with an installati<strong>on</strong>.<br />
<strong>VMware</strong> HA c<strong>on</strong>tinuously m<strong>on</strong>itors all ESX/ESXi hosts in a cluster and, in case of an ESX/ESXi host<br />
failure, restarts all affected virtual machines <strong>on</strong> the remaining hosts.<br />
Though <strong>VMware</strong> HA and <strong>VMware</strong> FT can provide ESX/ESXi server hardware protecti<strong>on</strong> to <str<strong>on</strong>g>SAP</str<strong>on</strong>g> single<br />
points of failure, it does not m<strong>on</strong>itor the health of the applicati<strong>on</strong> (that is, <str<strong>on</strong>g>SAP</str<strong>on</strong>g> database and Central<br />
Instance or Central Services). If applicati<strong>on</strong> level m<strong>on</strong>itoring is also required, then investigate using thirdparty<br />
clustering software in virtual machines (in-guest clustering), or a soluti<strong>on</strong> from Symantec, called<br />
Applicati<strong>on</strong>HA, which integrates with <strong>VMware</strong> HA. Table 1 summarizes the HA soluti<strong>on</strong>s.<br />
Table 1. Summary of High Availability Scenarios<br />
HA Scenario Hardware<br />
Protecti<strong>on</strong><br />
<strong>VMware</strong> HA<br />
<strong>VMware</strong> FT (SCS)<br />
Symantec<br />
Applicati<strong>on</strong>HA +<br />
<strong>VMware</strong> HA<br />
Applicati<strong>on</strong><br />
Aware<br />
Rolling Patch<br />
Upgrade<br />
Support<br />
Guest-OS boot Complexity<br />
after H/W failure Cost<br />
Yes No No Yes Low<br />
Yes Yes No Yes Medium<br />
In-guest Clustering Yes Yes Yes No High
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