HP Storage Mirroring V4.5 Software - Manual (Page 65)

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Case: Both source SQL servers have a database named “Accounting”
(
Source3\instance1|Accounting
and
Source4\instance2|Accounting
). You can
protect and failover each SQL server’s copy of the database without any issue.
Mirror type
The following options specify what files you want sent from the source to the target during a mirror.

Full—Copies all of the directories and files in the replication set to the target machine. If a mirror
has already been completed, another full mirror will overwrite the data on the target.

Checksum— (Default) This option performs a checksum comparison calculation. A checksum
calculation is a formula applied to blocks of data to determine if the binary make-up of the block
is identical. If the checksums on the source and target machine are the same, the block is skipped.
If the checksums on the source and target machine are not the same, the block on the source is
sent to the target. With this option, the entire file is not overwritten; only the block that is received
from the source is overwritten.
Enable compression
This setting enables compression of data that is transmitted from the source to the target. Significant
improvements in bandwidth utilization have been seen in Wide Area Network (WAN) configurations
or in any case where network bandwidth is a constraint.
Compression may be used in Local Area Network (LAN) configurations, though it may not provide any
significant network improvements.
You can specify compression for different source/target connections, but all connections to the same
target will have the same compression settings.
By default, compression is disabled. To enable it, select Enable Compression, then set the level
from minimum to maximum compression.
NOTE: All the database filenames (
*.mdf
,
*.ldf
, and
*.ndf
) must either be:

Uniquely named (for example,
accounting1.mdf
and
accounting2.mdf
), or

Uniquely located on the target (for example,
c:\Source3\accounting1\accounting1.mdf
and
c:\Source4\accounting2\accounting2.mdf
)
NOTE: The Mirror type setting also applies to the restoration connection.