VERITAS File System 4.1 Administrator's Guide

Quota
Quota Limits
Chapter 7128
Quota Limits
You can set limits for individual users to file and data block usage on a file system. You can set
two kinds of limits for each of the two resources:
• The hard limit is an absolute limit that cannot be exceeded under any circumstances.
• The soft limit, which must be lower than the hard limit, can be exceeded, but only for a
limited time. The time limit can be configured on a per-file system basis only. The VxFS
default limit is seven days.
A typical use of soft limits is when a user must run an application that could generate large
temporary files. In this case, you can allow the user to exceed the quota limit for a limited
time. No allocations are allowed after the expiration of the time limit. Use the edquota
command to set limits (see “Using Quotas” on page 129 for an example).
Although file and data block limits can be set individually for each user, the time limits apply
to the file system as a whole. The quota limit information is associated with user IDs and is
stored in a user quota file (see “Quota Files on VxFS” on page 128 ).
The quota soft limit can be exceeded when VxFS preallocates space to a file. See “Attribute
Specifics” on page 70 for information on extent allocation policies.
Quota limits cannot exceed two terabytes on a Version 5 disk layout.
Quota Files on VxFS
A quotas file (named quotas) must exist in the root directory of a file system for any of the
quota commands to work. The files in the root directory are referred to as the external quotas
file. VxFS also maintains an internal quotas file for its own use.
The quota administration commands read and write to the external quotas file to obtain or
change usage limits. VxFS uses the internal file to maintain counts of data blocks and inodes
used by each user. When quotas are turned on, the quota limits are copied from the external
quotas file into the internal quotas file. While quotas are on, all the changes in the usage
information and changes to quotas are registered in the internal quotas file. When quotas are
turned off, the contents of the internal quotas file are copied into the external quotas file so
that all data between the two files is synchronized.