HP XP P9500 Storage - Manual (Page 89)

allocated to the tier nearest to the specified tier. When a tier is over-commited, the tier to be
assigned is as follows:
◦ When tier 1 is over-committed, the pages are allocated to tier 2. If tier 2 is over-committed,
the unallocated pages are allocated to tier 3.
◦ When tier 2 is over-committed, the pages are allocated to tier 1. If tier 1 is over-committed,
the unallocated pages are allocated to tier 3.
◦ When tier 3 is over-committed, the pages are allocated to tier 2. If tier 2 is over-committed,
the unallocated pages are allocated to tier 1.
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If I/Os occur that exceed the I/O performance of the tier:
If the tiering policy on the THP V-VOL is set to all tiers, the tier range is considered and
the tier capacity and the limit performance are allocated. ◦
◦ However, if the tiering policy level on the THP V-VOL is set to a specific tier, the tier range
is considered and only the tier capacity is allocated. In this case, if I/O loads exceed the
assumed value, the tier to which a tiering policy is set may degrade I/O performance.
If you use the Tiering Policy function, configure tiers by considering the I/O loads.
Execution mode settings and tiering policy
The follow depicts how tier relocation is performed after changing the tiering policy setting while
Auto execution mode is used.
The following depicts two cases of how tier relocation is performed after changing the tiering policy
setting while Manual execution mode is used.
Smart Tiers 89