Oracle single-instance
As stated previously, the presence of a MetroCluster system does not necessarily add to or change any best practices for operating a database. The majority of databases currently running on customer MetroCluster systems are single instance and follow the recommendations in the Oracle on ONTAP documentation.
Failover with a preconfigured OS
SyncMirror delivers a synchronous copy of the data at the disaster recovery site, but making that data available requires an operating system and the associated applications. Basic automation can dramatically improve the failover time of the overall environment. Clusterware products such as Veritas Cluster Server (VCS) are often used to create a cluster across the sites, and in many cases the failover process can be driven with simple scripts.
If the primary nodes are lost, the clusterware (or scripts) is configured to bring the databases online at the alternate site. One option is to create standby servers that are preconfigured for the NFS or SAN resources that make up the database. If the primary site fails, the clusterware or scripted alternative performs a sequence of actions similar to the following:
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Forcing a MetroCluster switchover
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Performing discovery of FC LUNs (SAN only)
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Mounting file systems and/or mounting ASM disk groups
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Starting the database
The primary requirement of this approach is a running OS in place on the remote site. It must be preconfigured with Oracle binaries, which also means that tasks such as Oracle patching must be performed on the primary and standby site. Alternatively, the Oracle binaries can be mirrored to the remote site and mounted if a disaster is declared.
The actual activation procedure is simple. Commands such as LUN discovery require just a few commands per FC port. File system mounting is nothing more than a mount
command, and both databases and ASM can be started and stopped at the CLI with a single command. If the volumes and file systems are not in use at the disaster recovery site prior to the switchover, there is no requirement to set dr-force- nvfail
on volumes.
Failover with a virtualized OS
Failover of database environments can be extended to include the operating system itself. In theory, this failover can be done with boot LUNs, but most often it is done with a virtualized OS. The procedure is similar to the following steps:
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Forcing a MetroCluster switchover
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Mounting the datastores hosting the database server virtual machines
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Starting the virtual machines
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Starting databases manually or configuring the virtual machines to automatically start the databases For example, an ESX cluster could span sites. In the event of disaster, the virtual machines can be brought online at the disaster recovery site after the switchover. As long as the datastores hosting the virtualized database servers are not in use at the time of the disaster, there is no requirement for setting
dr-force- nvfail
on associated volumes.