Quotas

• Quotas are imprecise. Processes that are writing to the filesystem will be stopped a short time after the quota limit isreached. They will inevitably be allowed to write some amount ofdata over the configured limit. How far over the quota they areable to go depends primarily on the amount of time, not the amountof data. Generally speaking writers will be stopped within 10s ofseconds of crossing the configured limit.

• _Quotas are implemented in the kernel client 4.17 and higher._Quotas are supported by the userspace client (libcephfs, ceph-fuse).Linux kernel clients >= 4.17 support CephFS quotas but only onmimic+ clusters. Kernel clients (even recent versions) will failto handle quotas on older clusters, even if they may be able to setthe quotas extended attributes.

• Snapshot file data which has since been deleted or changed does not counttowards the quota. See also: http://tracker.ceph.com/issues/24284

Configuration

Like most other things in CephFS, quotas are configured using virtualextended attributes:

If the attributes appear on a directory inode that means a quota isconfigured there. If they are not present then no quota is set onthat directory (although one may still be configured on a parent directory).

To set a quota:

To view quota settings:

To remove a quota: