HP Storage Mirroring V5.1 Software - Manual (Page 188)

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will vary depending on the type of file activity and other variables. For instance, it will not
affect the overall performance of large database files much (since there is a lot of data, but
only a few file permissions), but may affect the performance of user files significantly (since
there are often thousands of files, each with permissions). In general, the performance
impact will only be noticed during mirrors since that is when the target workload is greatest.

Ignore Delete Operations—This option allows you to keep files on the target machine after they
are deleted on the source. When a file is deleted on the source, that delete operation is not sent
to the target. (All edits to files on the source are still replicated to the target; only deletions of
whole files are ignored.) This option may be useful to give you an opportunity to make a backup
of these files in the event they are needed in the future.

Maximum Pending Mirror Operations—This option is the maximum number of mirror
operations that are queued on the source. The default setting is 1000 . If, during mirroring, the
mirror queued statistic regularly shows low numbers, for example, less than 50 , this value can
be increased to allow Storage Mirroring to queue more data for transfer.

Size of Mirror Packets—This option determines the size of the mirror packets that Storage
Mirroring transmits. The default setting is 65536 bytes. You may want to consider increasing this
value in a high latency environment (greater than 100ms response times).

Block Checksum All Files on a Difference Mirror—This option allows a file difference mirror
to check each block of data, regardless of the file attributes. If this option is not marked, Storage
Mirroring will assume files are synchronized if their attributes match.
NOTE: Regardless of the security model you are using, if you create new user accounts on
the source, you should start a remirror so the new new user account information
associated with any files in your replication set can be transmitted to the target.
NOTE: If a file is deleted using Windows Explorer or My Computer, the file is not actually
deleted, from the file system perspective, but is moved to the Recycle Bin. Because
Storage Mirroring sees this as a move to outside of the replication set and not as a
delete, the file will still be deleted from the target even if you have Ignore Delete
Operations selected.
If delete operations are ignored long enough, the potential exists for the target to run
out of space. In that case, you can manually delete files from the target to free space.
NOTE: Database applications may update files without changing the date, time, or file size.
Therefore, if you are using database applications, you should use the Block Checksum
All option to ensure proper file comparisons.
If you are not using any database applications, disabling this option will shorten
mirror times.