Reserving tier capacity when setting a tiering policy
If you set the tiering policy of a DP-VOL, the DP-VOL used capacity and the I/O performance limitation are reserved from the tier. The reserved limit performance per page is calculated as follows:
The reserved limit performance per page = (The performance limit of the tier) รท (The number of pages in the tier).
A DP-VOL without a tiering policy setting uses the unreserved area in the pool.

