Administering Storage Policies

Manage storage policies related to data tiering.

You can configure a storage policy (or rules) for data at the volume level.

A storage policy simplifies the lifecycle management of data in the volume including automated migration of files to low-cost storage alternatives. A storage policy contains rules for files that have a well-defined lifecycle or for files you want to switch to different storage tiers during their lifecycle.

You can specify the rules, at the volume level, to selectively identify files to offload (such as file size, file owner, and file modification time), the schedule for offloading the data (for example, two months after file modification), and the settings for storing (such as the location and credentials for the tier) and recalling the offloaded data. You can configure one rule per volume. You can also associate a schedule to automatically offload data at scheduled intervals based on the associated rules.

Data offload is driven by rules, which are configured per volume. Data offload rule can be based on size of file (s), owner (u, g, or p) of the file, and/or file modification timestamp (m). You can apply one rule per volume.

When a rule is associated with a volume, the rule is first applied on the files in the tiering-enabled volume. When applied on the files in the tiering-enabled volume, the offload is triggered for all files in the snapshot chain as well when the criteria in the rule is met. If the file does not exist in the tiering-enabled volume, rule is applied on the latest state of the file in the snapshot chain. If the file exists in the tiering-enabled volume but has no latest state or if the file was deleted in the tiering-enabled volume, offload does not happen.

Rules can be defined using a combination of the following:

u Username or user ID, as configured in the OS registry (such as /etc/passwd file, LDAP, etc.), of a specific user.

Usage: u:<username or user ID>
g Group name or group ID, as configured in the OS registry (such as /etc/group file, LDAP, etc.), of a specific group.

Usage: g:<groupname or group ID>
a (atime) Time (in seconds or days) since the files were last accessed. The number of seconds can be specified by appending s to value and the number of days can be specified by appending d to the value.

Usage:

NOTE: If the system time on CLDB and file server nodes are different, the atime rule for offloading data may not work as intended.

This tier rule is matched and files are offloaded, when all of the following conditions are met:

Assume that the atime feature is enabled on the volume and that the time in the rule is set to a:300s. Based on this rule, all files that are not accessed since 300s, are offloaded. However, this rule is valid only if time since atime tracking is enabled, is more than 300s. The volume level parameter atimeTrackingStartTime denotes the start time of atime.

For more information, see Tuning Last Access Time.
m (mtime) Time (in seconds or days) since the files were last modified. The number of seconds can be specified by appending s to value and the number of days can be specified by appending d to the value.

Usage:

All files that are not modified since the specified amount of time, are offloaded.NOTE: If the system time on CLDB and file server nodes are different, the mtime rule for offloading data may not work as intended.
s The size of the file in bytes, kilobytes, megabytes, or gigabytes. The size of the file can be specified by appending one of the following to the value: b for bytes, k for kilobytes, m for megabytes, or g for gigabytes.

Usage

All files whose size exceeds the specified size are offloaded.
Or, use the following:
p (Default) Specifies all files. Specifies that this operation is applicable to all the files without restriction. This cannot be combined with any other operator.
"" Indicates none of the files. Specifies that this operation cannot be performed on any of the files.
Use the following to string multiple criteria for offload:
& AND operation to combine multiple expressions as the criteria for the rule.
| OR operation to indicate either of the expressions as the criteria for the rule.
() Delimiters for subexpressions.