HP StorageWorks Storage Mirroring for Linux User's Guide (T2558-96317, June 2009)

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Queue
The Queue tab contains settings for Storage Mirroring queue usage.
 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 daemon has been restarted on the server.
Select a location on a 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.
 Maximum system memory for queue—This is the amount of system memory, in MB, that will
be used to store data in queues. When exceeded, queuing to disk will be triggered. This value is
dependent on the amount of physical memory available but has a minimum of 32 MB. By default,
128 MB of memory is used. If you set it lower, Storage Mirroring will use less system memory,
but you will queue to disk sooner which may impact system performance. If you set it higher,
Storage Mirroring will maximize system performance by not queuing to disk as soon, but the
system may have to swap the memory to disk if the system memory is not available.
Since the source is typically running a production application, it is important that the amount of
memory Storage Mirroring and the other applications use does not exceed the amount of RAM in
the system. If the applications are configured to use more memory than there is RAM, the
system will begin to swap pages of memory to disk and the system performance will degrade.
For example, by default an application may be configured to use all of the available system
memory when needed, and this may happen during high-load operations. These high-load
operations cause Storage Mirroring to need memory to queue the data being changed by the
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.