There are two environments in which the use of independent disk pools can
be beneficial: a multiple-system clustered environment and a single-system
environment.
Multiple-system clustered environment
In a multiple-system
clustered environment, where the servers are members of an iSeries™ cluster
and an independent disk pool is associated with a switchable device in that
cluster, independent disk pools can be switched between systems without having
to perform an initial program load (IPL). The independent disk pool can be
switched because the independent disk pool is self-contained. This can be
a significant advantage because it allows for continuous availability of
data, the primary benefit of independent disk pools.
Switchable independent
disk pools can help you do the following:
- Keep data available to an application even in the event of a single system
outage, either scheduled or unscheduled.
- Eliminate the process of replicating data from one system to another.
- In some situations, isolate disk unit failures within the independent
disk pool.
- Achieve high availability and scalability.
A multiple-system environment also gives you the opportunity
to perform geographic mirroring. Geographic mirroring allows you
to maintain two identical copies of an independent disk pool at two sites
that are geographically separated. By having a second copy of critical data
at a remote location, you ensure greater protection and availability; for
example, in the case of a natural disaster. If you configure the independent
disk pools to be switchable, you increase your options to have more backup
nodes to allow for failover and switchover of independent disk pools between
systems at the same site, in addition to switchover and failover to a system
at another site.
Single-system environment
In a single-system environment,
where an independent disk pool is privately connected to a single server,
independent disk pool or independent disk pool groups can be made unavailable,
independent of other disk pools because the data in the independent disk
pool or independent disk pool group is self-contained. The independent disk
pool or independent disk pool group can also be made available, while the
system is active, without having to perform an IPL. Using independent disk
pools this way can be useful, for example, if you have large amounts of data
that are not needed for normal day-to-day processing. The independent disk
pool containing this data can be left offline until it is needed. When large
amounts of storage are normally kept offline, you can shorten processing
time for operations such as IPL and reclaim storage.
Single-system independent
disk pools can help you do the following:
- Isolate low-use data with the ability to bring the independent disk pool
online only when it is needed.
- Reduce system start time.
- Manage save and restore by independent disk pool.
- Reclaim storage by independent disk pool.
- Divide data between multiple databases.
- Isolate data associated with specific applications or associated with
specific groups of users.
- Consolidate data on small systems to independent disk pools
on a larger system. For example, in the case of multiple branch offices.
- Perform application maintenance that does not affect the entire system.