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Understanding Xsan Quotas

Xsan enforces two disk space quotas for each user or group you choose to restrict: a soft quota and a hard quota. You can set these in combination to establish clear limits on the amount of storage a user or group can use, while still allowing temporary access to extra space for unexpected storage needs. You specify quotas individually for each volume on a SAN. A user who has no quotas specified can use all available space on a volume. There are a few options to consider when choosing and setting quotas:

  • Soft quota—The maximum space a user or group is expected to occupy on a regular basis. It is “soft” because it can be exceeded by an amount up to the hard quota for a grace period that you specify.

  • Hard quota—The absolute limit on the space a user or group can occupy. Users are prevented from using more space than specified by their hard quotas.

  • Grace period—A user or group can exceed the soft quota without penalty as long as each returns below the soft quota within the grace period you specify.

  • Soft quotas change to hard quotas—If a user or group exceeds the soft quota for a time longer than the grace period, the soft quota is changed to a hard quota. The user or group will not be able to save additional data on the volume until the user or group members delete enough old files to bring their usage below the soft quota.

To understand how quotas work, assume you have assigned John Wolfe a soft quota of 75 GB, a hard quota of 100 GB, and a grace period of 48 hours. John’s files can occupy up to 75 GB of space at any time, for as long as he needs them. If John unexpectedly needs to use additional files or unusually large files, he can still copy them to the volume, up to a total of 100 GB. Then he has 48 hours to remove the files and return below his 75 GB soft limit. If he is using more than 75 GB after 48 hours, Xsan resets his hard quota to 75 GB and he is forced to reduce his storage use. John is unable to copy or save additional files to the volume until he deletes enough to return below the 75 GB quota.

Checking User Quota Status

You can use Xsan Admin to check file system quotas and see how much allotted storage each user and group is using.

To view quota status, follow these steps:

  1. In Xsan Admin, in the SAN Assets list, choose “Users and Groups” or Quotas.

    You see Users and Groups only if you chose Xsan Admin to manage your users and groups. Otherwise, you see Quotas.

  2. To be sure you’re seeing current information, click Refresh at the top of the window.

    Xsan Admin displays the following information for each user or group:

    • Used: The amount of storage space the user’s files are occupying.
    • Quota: The soft and hard quotas. For example, “500 MB – 1 GB” indicates a soft quota of 500 MB and a hard quota of 1 GB.
    • Quota Status: The status bar represents the full allocation, ranging from zero on the left to the hard quota on the right. The small vertical line within the bar identifies the soft quota. The colored portion of the bar shows how much space the user or group is currently using. A green bar indicates that the user or group is below the soft quota. A yellow bar indicates usage exceeding the soft quota but for a time period that remains within the grace period. A red bar indicates that the user has reached the hard quota, possibly because the soft quota was exceeded beyond the grace period and was changed to a hard quota.

SAN client users who don’t have access to Xsan Admin can use the Xsan Quotas application to check their own quotas.

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