The disk/xfs isolator uses XFS project quotas to track the disk space used by each container sandbox and to enforce the corresponding disk space allocation. When quota enforcement is enabled, write operations performed by tasks exceeding their disk allocation will fail with an EDQUOT error. The task will not be terminated by the containerizer.
To enable the XFS Disk isolator, append disk/xfs to the --isolation flag when starting the agent.
The XFS Disk isolator supports the --enforce_container_disk_quota flag. If enforcement is enabled, the isolator will set both the hard and soft quota limit. Otherwise, no limits will be set, Disk usage accounting will be performed but the task will be allowed to exceed its allocation.
The XFS Disk isolator requires the sandbox directory to be located on an XFS filesystem that is mounted with the pquota option. There is no need to configure projects or projid files. The range of project IDs given to the --xfs_project_range must not overlap any project IDs allocated for other uses.
The xfs_quota command can be used to show the current allocation of project IDs and quota. For example:
$ xfs_quota -x -c "report -a -n -L 5000 -U 10000"
To show which project a file belongs to, use the xfs_io command to display the fsxattr.projid field. For example:
$ xfs_io -r -c stat /mnt/mesos/
Project IDs are not reclaimed until the sandboxes they were assigned to are garbage collected. The XFS Disk isolator periodically checks if sandboxes of terminated containers still exist and deallocates project IDs of the ones that were removed. Such checks are performed at intervals specified by the --disk_watch_interval flag. Current number of available project IDs and total number of project IDs used by the isolator can be tracked using containerizer/mesos/disk/project_ids_free and containerizer/mesos/disk/project_ids_total metrics.
The XFS Disk isolator flag --xfs_kill_containers will create container quotas that have a gap between the soft and hard limits. The soft limit is equal to the limit requested for the disk resource and the hard limit is 10MB higher. If a container violates the soft limit then it will be killed. The isolator polls for soft limit violations at the interval specified by the --container_disk_watch_interval flag.
Note that the --container_disk_watch_interval flag only applies to the XFS Disk isolator when --xfs_kill_containers is set to true.