HP Storage Mirroring V5.1 Software - Manual (Page 185)

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Queue
The Queue tab contains settings for Storage Mirroring queue usage.
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Folder—This is the location where the disk queue will be stored. Storage Mirroring displays the
amount of free space on the volume selected. Any changes made to the queue location will not
take effect until the Storage Mirroring service has been restarted on the server.
Select a location on a non-clustered volume that will have minimal impact on the operating
system and applications being protected. For best results and reliability, this should be a
dedicated, non-boot volume. The disk queue should not be on the same physical or logical
volume as the data being replicated. Also, for best results, select a location that is on a different
volume as the location of the Windows pagefile.
Although the read/write ratio on queue files will be 1:1, optimizing the disk for write activity will
benefit performance because the writes will typically be occurring when the server is under a
high load, and more reads will be occurring after the load is reduced. Accordingly, use a
standalone disk, mirrored (RAID 1) or non-parity striped (RAID 0) RAID set, and allocate more
I/O adapter cache memory to writes for best performance. A RAID 5 array will not perform as
well as a mirrored or non-parity striped set because writing to a RAID 5 array incurs the
overhead of generating and writing parity data. RAID 5 write performance can be up to 50% less
than the write performance of a single disk, depending on the adapter and disk.
Another option is to use a solid state disk, which are hard drives that use RAM instead of disk
platters. These devices are typically quite costly, but they will provide superior performance as a
queuing device when the best performance is required.
NOTE: Scanning the Storage Mirroring queue files for viruses can cause unexpected results.
If anti-virus software detects a virus in a queue file and deletes or moves it, data
integrity on the target cannot be guaranteed. As long as you have your anti-virus
software configured to protect the actual production data, the anti-virus software can
clean, delete, or move an infected file and the clean, delete, or move will be replicated
to the target. This will keep the target from becoming infected and will not impact the
Storage Mirroring queues.