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SC Series array
19 Dell EMC SC Series Arrays with MySQL | 3063-BP-O
3.6 Datapage
A datapage is the space that is allocated from the Assigned disk folder to a volume when a request for space
is made. Possible datapage sizes are:
512 KB: This datapage size is appropriate for application programs with high performance needs, or
environments in which snapshots (replays) are taken frequently under heavy I/O. Selecting this size reduces
the amount of space System Manager can present to servers. Flash-optimized storage types use 512 KB by
default.
2 MB: The default datapage size. This selection is appropriate for most application program needs.
4 MB: This datapage size is appropriate for configurations that use a large amount of disk space with
infrequent snapshots.
Caution: Dell EMC strongly recommends using the default datapage size for MySQL. If there is a need to
change the datapage value, consult with Dell Support to assess the performance impact and to ensure
system resources remain balanced after changing the datapage size.
When creating a volume, the SC Series system assigns the volume a maximum size as requested. Once the
volume is presented to a server, space (datapages) will either be assigned to the volume from the pagepool
all at once or when data is written to the volume. For best practices on volume space allocation in MySQL
environments, see section 3.22, Preallocating storage.
3.7 Tiered storage
All disk space within the pagepool is allocated into one of three tiers. A tier defines the type of storage media
used to save the data. When only two types of disks are used in an SC Series array, the array automatically
creates two tiers of storage. The fastest disks are placed in tier 1, and higher capacity, cost-efficient disks with
lower performance metrics are assigned to tier 3. When three types of disks are used, the array automatically
creates three tiers of storage.