6.5 HP StoreAll OS User Guide

22 Using data tiering
A data tier is a logical grouping of file system segments. After creating tiers containing the segments
in the file system, you can use the data tiering migration process to move files from the segments
in one tier to the segments in another tier.
For example, you could create a primary data tier for SAS storage and another tier for SATA
storage. You could then migrate specific data from the SAS tier to the lower-cost SATA tier. Other
configurations might be based on the type of file being stored, such as storing all streaming files
in a tier or moving all files over a certain size to a specific tier.
You can create any number of data tiers. A tier cannot be on tape or on a location external to the
StoreAll file system, such as an NFS share.
StoreAll data tiering is transparent to users and applications and is compatible with StoreAll
software file system snapshots and other StoreAll data services.
IMPORTANT:
• Migration is a storage and file system intensive process which, in some circumstances, can
take days to complete. Migration tasks are best to be run at a time when clients are not
generating significant load. Migration is not suitable for environments where there are no
quiet times to run migration tasks.
• Data tiering has a cool-down period of approximately 10 minutes. If a file was last accessed
during the cool-down period, the file is not moved.
Data tiering policy
A tiering policy specifies migration rules for the file system. One tiering policy can be defined per
file system and the policy must have at least one rule. Rules in the policy can migrate files between
any two tiers in the file system. For example, Rule 1 could move files between Tier 1 and Tier 2,
Rule 2 could migrate files from Tier 2 to Tier 1, and Rule 3 could migrate files between Tier 1 and
Tier 3.
A file is migrated according to the first rule that it matches. You can narrow the scope of rules by
combining directives using logical operators.
For example, you could create a policy that has three simple rules:
• Migrate all files that have not been modified for 30 days from Tier 1 to Tier 2.
• Migrate all files larger than 5 MB from Tier 1 to Tier 2.
• Migrate all MPEG-4 files from Tier 1 to Tier 2.
Changing the tiering configuration
The following restrictions apply when changing the configuration:
• You cannot modify the tiering configuration for a file system while an active migration task is
running.
• You cannot move segments between tiers, assign them to new tiers, or unassign them from
tiers while an active migration task is running or while any rules exist that apply to the segments.
Creating and managing data tiers
You can use the Data Tiering Wizard to create and manage data tiers. Select the file system on
the Management Console, and then select Active Tasks→Data Tiering in the lower Navigator. On
the Task Summary panel, click Data Tiering to open the wizard.
Creating and managing data tiers 377