Specifying target pool size

Specify target pool size.

A newly created pool consumes a small fraction of the total cluster capacity and appears to the system that it will need a small number of PGs. However, in most cases, cluster administrators know which pools are expected to consume most of the system capacity over time. If you provide this information, known as the target size to IBM Storage Ceph, such pools can use a more appropriate number of PGs (pg_num) from the beginning. This approach prevents subsequent changes in pg_num and the overhead associated with moving data around when making those adjustments.

You can specify target size of a pool by either using the absolute size of the pool or the total cluster capacity.