5.6 HP StorageWorks X9000 File Serving Software User Guide (TA768-96035, June 2011)

13 Using data tiering
This chapter describes how to configure and manage data tiering.
Overview
Use the data tiering feature to set a preferred tier where newly created files will be stored. Once
files are created, you can use a tiering job to move them from initial storage, based on file attributes.
When you start the tiering job, you can specify a desired number of file replicas to add (default
is 0).
• You can use any naming convention you choose to identify each tier grouping.
• You can create as many named tiers as your environment requires.
• A segment can belong to only one tier at a time, but it can be reassigned at any time.
Assigning file system segments to distinct tiers allows you to categorize areas in your file system
and storage network. After the tiers are created, you can use rule-based commands to automatically
move files from tier to tier, based on file attributes.
For example, a storage network composed of newer and older drives might be tiered based on
the access speed of the storage media. Using descriptive tier names such as “fast” and “slow,”
you assign each segment in your file system to the appropriate tier, creating a tier of fast segments
and a tier of slower segments.
Using the migrator utility, you can write and execute rules that move frequently accessed files into
the fast storage tier, and move files that are rarely accessed to less expensive storage media in
the slow tier. This is just one example of moving files based on a tiering structure. Other examples
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.
IMPORTANT: Data tiering has a cool-down period of approximately 10 minutes. If a file was
last accessed during the cool-down period, the file will not be moved.
Moving files between tiers
X9000 Software allows you to set a preferred tier where newly created files will be stored. Once
files are created, you can use a tiering job to move them from initial storage, based on file attributes.
Tiering is the ability to programmatically move files from one tier to another in the same file system.
You write rules based on file attributes such as modification time, access time, file size, or file type
to define the tiering policy. The policy then determines which files are to be moved and when.
• A tiering policy (a set of rules) applies to individual files in a specific file system.
• If a file meets the criteria of a rule, it will be moved from its current tier to the rule’s target tier.
• A tiering policy (once configured) is executed via a command or as a cron job, and is
performed in the background by the system.
• Files created or changed within the last five minutes are considered active and will not be
moved.
Writing a rule to implement a policy
A tiering policy is defined by rules. Each rule identifies file attributes to match. It also specifies the
source tier to scan and the destination tier where files that meet the rule’s criteria will be moved
and stored.
108 Using data tiering