Apple Xsan 1.1 - Manual (Page 77)

Chapter 4 Managing Clients and Users 77
About 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 in a SAN. A user for whom no quotas
are specified can use all available space on a volume.
Soft Quota
The soft quota is 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 hard quota is an absolute limit on the space a user or group can occupy. Users are
prevented from using more space than specified by their hard quotas. If a user tries to
exceed his or her hard quota, he or she sees a message containing the error code -1425.
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, and the user or group will not be able to save
additional data on the volume until each deletes old files and returns below the soft
quota.
Example
Suppose you assign Aldo a soft quota of 75 GB, a hard quota of 100 GB, and a grace
period of 48 hours. Aldo’s files can occupy up to 75 GB of space at any time, for as long
as he needs them. If Aldo is surprised by additional or unusually large files, he can still
copy them to the volume, up to a total of 100 GB. He then has 48 hours to remove files
and return below the 75 GB soft limit. If he is still 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. Aldo is
unable to copy or save additional files to the volume until he deletes enough to return
below the 75 GB quota.