Managing quotas on virtual volumes

File Services Administration Guide for Hitachi NAS Platform
Version
14.7.x
14.6.x
Audience
anonymous
Part Number
MK-92HNAS006-29
Three types of quotas are maintained for each virtual volume:
  • Explicit User/Group Quotas. A quota explicitly created to impose restrictions on an individual user or group, defining a unique set of thresholds.
  • Default User/Group Quotas. A quota set automatically for all users and groups that do not have explicit quotas, set by defining a set of Quota Defaults (thresholds) for creating a quota automatically when a file is created or modified in the virtual volume. .

    Default quotas for virtual volumes operate in the same way as those defined for file systems. User (Group) quota defaults define a set of thresholds for creating a quota for a user (or group) the first time that user (or group) saves a file in the virtual volume.

    Initially, quota defaults are not set. When activity occurs in the virtual volume, it is tracked, but quotas are not automatically created. When at least one threshold is set to a non-zero value, a User or Group quota (as appropriate) will be created for the owner of the directory at the root of the virtual volume.

  • Virtual Volume & Quotas. A virtual volume quota tracks the space used within a specific directory on the virtual volume . A quota can be explicitly created to define a set of thresholds restricting all operations in the virtual volume, unrelated to which user or group initiated them.
Note: Quotas track the number and total size of all files. At specified thresholds, emails alert the list of contacts associated with the virtual volume and, optionally, Quota Threshold Exceeded events are logged. Operations that would take the user or group beyond the configured limit can be disallowed by setting hard limits.

When Usage and File Count limits are combined, the server will enforce the first quota to be reached.

Important information about virtual volumes and quotas

The server treats the virtual volume 'root' directory, together with all its sub-directories, as a self-contained file system. The virtual volume tracks its usage of space and number of files, to provide a way of monitoring file system usage. This tracking allows quotas to be imposed on disk space usage, as well as the total number of files.

Quotas can be set for the entire virtual volume, and on individual users, and on groups of users. Default user and group quotas can be defined, and in the absence of explicit user or group quotas, the default quotas apply.

The following caveats apply in measuring the virtual volume status against quota thresholds:
  • Metadata and snapshot files. Neither file system metadata nor snapshot files count towards the quota limits.
  • Symbolic link calculation. Files with multiple hard links pointing to them are included only once in the quota calculation. A symbolic link adds the size of the symbolic link file to a virtual volume and not the size of the file to which it links.