Appendix B. Higher Level Storage Management Products
This appendix is intended to provide an overview of some of the higher level
storage management products available. The products will be compared in
terms of function and positioning.
The main areas in which higher level tools provide enhanced function are:
The provision of mechanisms to define when information should be backed
up, archived or migrated, and what information should be selected. This
allows the defined operations to be scheduled as required without the need
for operator intervention.
The ability to create copies of a client system′s vital data, so that in the
event of a failure, the client can be restored to the same state that it was at
the time of the last backup.
The ability to free up space at the client system by moving or archiving
infrequently accessed information from the client to the archive storage
space (usually at a server machine). If the information is required again, it
can be retrieved from the archive.
The ability to structure the storage subsystems in such a way that elements
of the subsystem are used in the most efficient fashion. For example,
frequently accessed information, or information requiring high performance
access should be stored in fast storage (usually disk). Information that is
less frequently accessed should be moved to less expensive, lower
performance, higher capacity media such as optical; this should happen
automatically if possible, thereby freeing up space in the much in demand
fast storage. If the second level of storage (that used by the first movement,
or migration) of information becomes full, or for information that is accessed
even more rarely, a third level could be defined of even higher capacity,
cheaper, slower media, such as tape.
Levels in the hierarchy should also be accessible for specific purposes; for
example, backups, or long term archives would be best stored in the tape
5. Disk space utilization
A mechanism by which disk space on a client can be utilized more
efficiently. This is usually implemented by using the client disk as a cache,
and maintaining the full information space at a server. When data is
requested by an application on the client, it can be transparently copied to
the client cache - clients see the cache to be as large as the information
space at the server.
This can be used in conjunction with the capabilities mentioned in the
previous points. The server information space can be treated as a level in a
storage hierarchy, thereby increasing efficiency further. The space can also
be backed up more easily.
6. Central management
Copyright IBM Corp. 1994 337