HP Storage Mirroring Software - Manual (Page 176)

Workload protection Page 175 of 677
amount of physical memory available but has a minimum of 32 MB. By
default, 128 MB or 512 MB of memory is used, depending on your operating
system. If you set it lower, Storage Mirroring Recover will use less system
memory, but you will queue to disk sooner which may impact system
performance. If you set it higher, Storage Mirroring Recover 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 Recover 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 Recover to need memory to queue the data being changed
by the application. In this case, you would need to configure the applications
so that they collectively do not exceed the amount of RAM on the server.
Perhaps on a server with 1 GB of RAM running the application and Storage
Mirroring Recover, you might configure the application to use 512 MB and
Storage Mirroring Recover to use 256 MB, leaving 256 MB for the operating
system and other applications on the system. Many server applications
default to using all available system memory, so it is important to check and
configure applications appropriately, particularly on high-capacity servers.
Any changes to the memory usage will not take effect until the Storage
Mirroring service has been restarted on the server.
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Maximum disk space for queue—This is the maximum amount of disk
space, in MB, in the specified Folder that can be used for Storage Mirroring
Recover disk queuing, or you can select Unlimited which will allow the
queue usage to automatically expand whenever the available disk space
expands. When the disk space limit is reached, Storage Mirroring Recover
will automatically begin the auto-disconnect process. By default, Storage
Mirroring Recover will use an unlimited amount of disk space. Setting this
value to zero (0) disables disk queuing.
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Minimum Free Space—This is the minimum amount of disk space in the
specified Folder that must be available at all times. By default, 250 MB of
disk space will always remain free. The Minimum Free Space should be
less than the amount of physical disk space minus Maximum disk space for
queue.