Lustre 1.6 Operations Manual

9.1.3 Resetting the Quota
To reset the quota that was previously established for a user, run:
# setquota -u $user 0 0 0 0 /srv/testfs
Then run:
# setquota -u $user a b c d /srv/testfs
Caution – Do not use # lfs setquota to reset the previously-established quota.
9.1.4 Quota Allocation
The Linux kernel sets a default quota size of 1 MB. (For a block, the default is 100
MB. For files, the default is 5000.) Lustre handles quota allocation in a different
manner. A quota must be set properly or users may experience unnecessary failures.
The filesystem block quota is divided up among the OSTs within the filesystem.
Each OST requests an allocation which is increased up to the quota limit. The quota
allocation is then quantized to reduce the number of quota-related request traffic. By
default, Lustre supports both user and group quotas to limit disk usage and file
counts.
The quota system in Lustre is completely compatible with the quota systems used on
other file systems. The Lustre quota system distributes quotas from the quota master.
Generally, the MDS is the quota master for both inodes and blocks. All OSTs and the
MDS are quota slaves to the OSS nodes. The minimum transfer unit is 100 MB, to
avoid performance impacts for quota adjustments. The filesystem block quota is
divided up among the OSTs and the MDS within the file system. Only the MDS uses
the filesystem inode quota.
This means that the minimum quota for block is 100 MB* (the number of OSTs + the
number of MDSs), which is 100 MB* (number of OSTs + 1). The minimum quota for
inode is the inode qunit. If you attempt to assign a smaller quota, users maybe not
be able to create files. The default is established at filesystem creation time, but can
be tuned via /proc values (described below). The inode quota is also allocated in a
quantized manner on the MDS.
9-6 Lustre 1.6 Operations Manual • September 2008