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SC Series array
43 Dell EMC SC Series Arrays with MySQL | 3063-BP-O
Frozen preallocated pages
Therefore, for high-performance database systems, where performance can be affected by dynamic block
allocation, consider the tradeoff between preallocating and not preallocating space, especially if snapshots
are a requirement. Also, consider the tradeoff between expanding or not expanding a preallocated volume.
Choosing to preallocate upon volume creation means that applying a snapshot profile to the volume or
expanding the volume size at any point in the future will undo the benefit of preallocation. For this reason, Dell
EMC recommends that snapshots should never be used on preallocated volumes, and that preallocated
volumes should never be expanded.
Note: The option to Preallocate Storage is only available after the volume is presented to a server, and only
if Allow Preallocate Storage Selection option has been enabled in DSM and no data has been written to the
volume.
To preallocate storage, right-click a volume in the system tree of Storage Center and select Preallocate
Storage.
Preallocating storage on a volume
If Preallocate Storage is selected, the SC Series array will take from the pagepool the maximum size
specified for the volume. If the pagepool is 20 TB, and the maximum size for a volume is 1 TB, but only 1 MB
of data is written to the volume, the volume will be 1 TB in size after preallocation, and the pagepool will have
19 TB of remaining available space. The Preallocate Storage feature runs in the background and takes time
depending on the size of the volume being preallocated.
To see the progress of any preallocation, change the view in the SC Series interface to Background
Processes.
Progress on preallocation process