Use disk pools (auxiliary storage pool) to control which objects
are allocated to which groups of disk units. If you are journaling many active
objects to the same journal, the journal receiver can become a performance
bottleneck. One way to minimize the performance impact of journaling is to
put the journal receiver in a separate disk pool. This also provides additional
protection because your objects are on different disk units from the journal
receiver, which contains a copy of changes to the objects.
iSeries™ servers
have several types of disk pools:
- System disk pool
- The system disk pool contains the operating system. It can also contain
user libraries and objects. The system disk pool is always disk pool number
1.
- Basic disk pool
- Basic disk pools are disk pool numbers 2 through 32. A basic disk pool
can be a library or a non library disk pool. The differences are as follows:
- A library disk pool contains one or more user libraries or user-defined
file systems. It does not contain the operating system. This is the current
recommended method of configuring user disk pools.
- A non library disk pool contains no user libraries or user-defined file
systems. It may contain journals, journal receivers, and save files. If you
place a journal receiver in a non library basic disk pool, the journal must
be in either the system disk pool or the same non library disk pool. The journaled
objects must be in the system disk pool.
- Independent disk pool
- Independent disk pools are disk pools 33 through 255. If
you use independent disk pools, you can only put journals and journal receivers
on independent disk pools that are library capable. If you are going to place
the journal receiver in a switchable independent disk pool, the journal receiver,
the journal, and journaled object must be in the same disk pool group (though
they do not have to be in the same disk pool).
When disk pools were first introduced, they were called auxiliary storage
pools (ASPs). Only non library user ASPs were available. Many systems still
have this type of ASP. However, recovery steps are more complex for non library
user ASPs. Therefore, for systems implementing journaling for the first time,
library disk pools are recommended.
Journal management and independent disk pools has more specific information
about using journaling with independent disk pools. Manage disk units in disk
pools has specific information about disk pools. The Independent disk pools
topic has detailed information about setting up independent disk pools.