HP StorageWorks Storage Mirroring user's guide (T2558-96073, February 2008)

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Storage Mirroring operations
Storage Mirroring performs four basic types of operations.
 Mirroring—The initial copy or subsequent resynchronization of selected data
 Replication—The on-going capture of byte-level file changes
 Failure monitoring and failover—The ability to monitor and stand-in for a server, in the event of a failure
 Restoration—A mirror of selected data from the target back to the source
Special Storage Mirroring add-ons and features, as discussed under
Storage Mirroring add-ons and features on page 2-6, build
on these core operations to provide greater protection for different environments and needs.
Mirroring
Mirroring is the process of transmitting user-specified data from the source to the target so that an identical copy of data
exists on the target. When Storage Mirroring initially performs mirroring, it copies all of the selected data, including file
attributes and permissions. Mirroring creates a foundation upon which Storage Mirroring can efficiently update the target
server by replicating only file changes.
If subsequent mirroring operations are necessary, Storage Mirroring can mirror specific files or blocks of changed data within
files. By mirroring only files that have changed, network administrators can expedite the mirroring of data on the source and
target servers.
Mirroring has a defined end point - when all of the selected files from the source have been transmitted to the target. When
a mirror is complete, the target contains a copy of the source files at that point in time.
Source
Target
2/4
1/29
All files can be mirrored
Checksums can calculate
blocks to be mirrored
Different files can
be mirrored
New files are mirrored
Identical files are
not mirrored
Flexible mirroring options allow you to choose
while files are mirrored from the source to the target.