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Shutting Down a Clustered Configuration (CLI)
Cluster Two Paths
FIGURE 21
Related Topics
"Shutting Down a Clustered Configuration (CLI)" on page 199
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Estimating and Reducing Takeover Impact
There is an interval during takeover and failback during which access to storage cannot be
provided to clients. The length of this interval varies by configuration, and the exact effects on
clients depends on the protocol(s) they are using to access data. Understanding and mitigating
these effects can make the difference between a successful cluster deployment and a costly
failure at the worst possible time.
NFS (all versions) clients typically hide outages from application software, causing I/O
operations to be delayed while a server is unavailable. NFSv2 and NFSv3 are stateless protocols
that recover almost immediately upon service restoration. NFSv4 incorporates a client grace
period at startup, during which I/O typically cannot be performed. The duration of this grace
period can be tuned in the Oracle ZFS Storage Appliance; reducing it will reduce the apparent
impact of takeover and/or failback. For planned outages, the Oracle ZFS Storage Appliance
provides grace-less recovery for NFSv4 clients, which avoids the grace period delay. For
more information about grace-less recovery, see the Grace period property in
"NFS Service
Properties" on page
237.
Configuring the Appliance
221
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