VNX: Unable to unmount/delete filesystem or checkpoint errors: Device or resource busy/path is unavailable(frozen) or invalid

Attempting to delete or unmount a file system or checkpoint

Trying to unmount/delete file systems fscommon_03 and fscommon_05 and getting the error;

Delete file system fscommon_03. vdm01 : Device or resource busy.

A race condition caused by range locks held on a CIFS file even though the file was closed. This caused a variety of symptoms including: Failure to access the file from a CIFS client; An unmount of the File System hung; A freeze of the File System hung.

Review of the /nas/log/cmd_log.err file and server_log shows the following symptoms;

[nasadmin@CS0 ~]$ tail /nas/log/cmd_log.err
2016-03-23 15:20:40.228 vdm01:517:7580:E: server_umount vdm01 -perm fscommon_03: Device or resource busy
2016-03-23 15:21:09.155 vdm01:517:9117:E: server_umount vdm01 -perm fscommon_05: Device or resource busy
2016-03-23 15:47:32.895 vdm01:517:29927:E: server_umount vdm01 -perm fscommon_03: Device or resource busy
2016-03-23 15:48:05.181 vdm01:517:30473:E: server_umount vdm01 -perm fscommon_05: Device or resource busy
2016-03-24 10:16:10.064 vdm01:517:12748:E: server_umount vdm01 -perm fscommon_05: Device or resource busy
2016-03-24 10:17:20.837 vdm01:517:15520:E: server_umount vdm01 -perm fscommon_03: Device or resource busy
2016-03-24 10:25:41.265 vdm01:517:29433:E: server_umount vdm01 -perm fscommon_03: Device or resource busy

[nasadmin@CS0 ~]$ server_log server_2 |grep -i frozen |tail -10
2016-03-24 12:07:59: CFS: 6: /root_vdm_1/fscommon_03: path is unavailable(frozen) or invalid.
2016-03-24 12:07:59: CFS: 6: /root_vdm_1/fscommon_05: path is unavailable(frozen) or invalid.
2016-03-24 12:09:07: CFS: 6: /root_vdm_1/fscommon_03: path is unavailable(frozen) or invalid.
2016-03-24 12:09:07: CFS: 6: /root_vdm_1/fscommon_05: path is unavailable(frozen) or invalid.
2016-03-24 12:09:07: CFS: 6: /root_vdm_1/fscommon_03: path is unavailable(frozen) or invalid.
2016-03-24 12:09:07: CFS: 6: /root_vdm_1/fscommon_05: path is unavailable(frozen) or invalid.
2016-03-24 12:09:08: CFS: 6: /root_vdm_1/fscommon_03: path is unavailable(frozen) or invalid.
2016-03-24 12:09:08: CFS: 6: /root_vdm_1/fscommon_05: path is unavailable(frozen) or invalid.
2016-03-24 12:09:08: CFS: 6: /root_vdm_1/fscommon_03: path is unavailable(frozen) or invalid.
2016-03-24 12:09:08: CFS: 6: /root_vdm_1/fscommon_05: path is unavailable(frozen) or invalid.

Workaround:

Failover or reboot the affected data mover where the file system or ckeckpoint is currently mounted. Once completed, the unmount/deletion of the file system or checkpoint can be completed without further issues.

Perm Fix:
VNX1 Series: 7.1.74.505, 7.1.76.415 and higher code levels
VNX2 Series: 8.1.3.72 and higher