HP Storage Mirroring Software - Manual (Page 113)

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! ! ! ! Verification
Verification
Verification is the process of confirming that the data on the target is identical to the data on the source. Verification creates
a log file detailing what was verified as well as which files are not synchronized. If the data is not the same, Storage Mirroring
can automatically initiate a remirror. The remirror ensures data integrity between the source and target.
Verification Options
In the Storage Mirroring Management Console, verification can be configured when a connection is established or initiated
manually at any time. (Verification cannot be initiated while a mirror is occuring.) Verification can also be scheduled to occur
at periodic intervals. In the Storage Mirroring Text Client, verification can only be initiatied after a connection is established.
In either case, you must specify how you want the Storage Mirroring verification process to execute. The following options
can be set:
! Start Time —The start time specifies the time for the verification process to begin.
! Verification Interval —The verification interval specifies how often the verification process will be repeated. This interval
can be as short as minutes or as long as days.
! Remirror —You can configure Storage Mirroring to automatically perform a remirror for only those files that are not
synchronized on the source and target. If the verify process indicates that the files are identical on both machines, the
remirror is not performed. There are two remirror options available when verification has found inconsistencies:
! Only if newer on source —If a file on the source is newer than the file on the target based on date and time stamps,
the file is mirrored to the target machine. This option overwrites the file on the target machine. If the file on the
target is newer, the file on the source is not mirrored to the target.
! Block checksum —With this option, each file that fails the verification process is read in blocks to determine which
blocks are not identical. Those blocks that are different are sent to the target machine. With this option, the entire
file is not overwritten on the target machine; just the dissimilar blocks.
The following table illustrates how the remirror options work together, as well as how they work with the global
checksum setting on the Source tab of the Server Properties. Determine which options you need to select when
configuring verification by identifying which type of action you want Storage Mirroring to perform during the verification.
NOTE: Because of the way the Windows Cache Manager handles memory, machines that are doing minimal or light
processing may have file operations that remain in the cache until additional operations flush them out. This
may make Storage Mirroring files on the target appear as if they are not synchronized. When the Windows
Cache Manager releases the operations in the cache on the source, the files will be updated on the target.
NOTE: Verification does not identify files that exist on the target that are no longer on the source machine. See orphan
files for information on deleting files on the target that no longer exist in the source replication set.