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Figure 11-4 Auto Tiering Relocation
11.2.4. Tiering Policies
For a best performance in various environments, auto tiering has a completely automated
feature that implements a set of tiering polices. Tiering policies determine how new
allocations and ongoing relocations should apply within a volume for those requirements.
Auto tiering uses an algorithm to make data relocation decisions based on the activity level
of each unit. It ranks the order of data relocation across all volumes within each separate
pool. The system uses this information in combination with the tiering policy per volume to
create a candidate list for data movement. The following volume policies are available:
Auto Tiering
It allows moving a small percentage of the “hot” data to higher tiers while maintaining the
rest of the data in the lower tiers. This policy automatically relocates data to the most
appropriate tier based on the activity level of each data. Sub LUNs are relocated based on
the highest performance disk drives available and its hotness. Although this setting
relocates data based on the performance statistics of the volume, the volume sets with
“Highest available Tier” take precedence. Initial space is allocated in the tier which is
healthier and has more free capacity than other tiers, then relocated according to hotness of
the data. This is the recommended policy and it is the default policy for each newly created
volume.