VNX, eNas: Permission denied errors after extending a file system

The below errors are reported when extending a user file system:

[nasadmin@eNasCS ~]$ nas_fs -xtend filesystemexample size=300G pool=filepool -option slice=yes
/nas/sbin/build_config: line 368: /nas/dos/slot_2/boot.cpy: Permission denied
/nas/sbin/build_config: line 368: /nas/dos/slot_2/boot.cpy: Permission denied
/nas/sbin/build_config: line 368: /nas/dos/slot_2/boot.cpy: Permission denied
id        = 40
name      = filesystemexample

Making configuration changes to a file system using CLI or UI may cause 'permission denied' errors to /nas/dos/slot_x/boot.cpy where 'x' is the slot number where the file system is mounted.

[nasadmin@Whatchamacallit-CS1 ~]$ ls -lh /nas/dos
lrwxrwxrwx 1 root root 11 Jul  1  2011 /nas/dos -> /nbsnas/dos

File system manages to extend, however there are permission denied errors reported during the rebuild of the slot_x boot.cfg file.

Any type of NAS configuration change causes a rebuild of the boot.cfg configuration file located in /nbsnas/dos/slot_x ('x' is the slot number of the data mover where the file system is mounted) and during this process a temporary file boot.cpy is created.

The file system can be extended, however 'permission denied' errors are reported against the boot.cpy file which may indicate an issue during the rebuild of the boot.cfg located in /nas/dos/slot_x.

Partition /nbsnas/dos was manually mounted using the below command:

mount /dev/sda1 /nbsnas/dos

As a result, the partition was mounted as a vfat type file system and the group owner was changed to 'root' (rather than nasadmin) causing permission issues with the partition.

Incorrect permissions:

pwd: /nbsnas
drwxr-xr-x 22 root root 16K Dec 31 1969 dos

pwd: /nbsnas/dos
-rwxr-xr-x 1 root root 52 Nov 6 2018 boot.bat
-rwxr-xr-x 1 root root 148K Jun 21 17:08 boot.cfg

Correct permissions:

pwd: /nbsnas
drwxrwxr-x 22 root nasadmin 16K Dec 31 1969 dos

pwd: /nbsnas/dos
-rwxrwxr-x 1 root nasadmin 52 Sep 7 2022 boot.bat
-rwxrwxr-x 1 root nasadmin 2.2K Jun 21 03:21 boot.cfg

The main cause of the issue is that the 'group' owner of the dos and boot files is 'root' when it should be 'nasadmin'. 

/nbsnas/dos should be mounted as an MSDOS file system. In this case, /nbsnas/dos is mounted as a vfat file system.

Command 'mount' shows the type of file system, we can also check the /etc/fstab file on the control station:

Incorrect mount of file system /nbsnas/dos:

• eNas:

/dev/sda1 on /nbsnas/dos type vfat (rw)

• VNX:

/dev/nda1 on /nbsnas/dos type vfat (rw)

Correct mount of file system /nbsnas/dos:

• eNas:

/dev/sda1 on /nbsnas/dos type msdos (rw,sync,umask=002,gid=201)

• VNX:

/dev/nda1 on /nbsnas/dos type msdos (rw,sync,umask=002,gid=201)

Remount the file system as the correct file system type MSDOS:

1. Confirm that the /etc/fstab file is correct and matches the following:

• eNas:

[nasadmin@CS0 ~]$ cat /etc/fstab | grep dos
/dev/sda1       /nas/dos                msdos   noauto,rw,sync,umask=002,gid=201        0 0

• VNX:

[nasadmin@Whatchamacallit-CS1 ~]$ cat /etc/fstab | grep dos
/dev/nda1       /nas/dos                msdos   noauto,rw,sync,umask=002,gid=201        0 0

2. Unmount and then remount the /nas/dos partition using step 2a or 2b:
   1. Failover or failback control station per Dell article 25261, Celerra, VNX Unified: How to fail over or fail back a Control Station (User Correctable) 

2. Manually unmount and remount the /nas/dos partition:

umount /nas/dos
mount /nas/dos

3. Verify the /nas/dos is mounted as MSDOS:

• eNas:

[nasadmin@CS0 ~]$ mount -t msdos
/dev/sda1 on /nbsnas/dos type msdos (rw,sync,umask=002,gid=201)

• VNX:

[nasadmin@Whatchamacallit-CS1 nasadmin]# mount -t msdos
/dev/nda1 on /nbsnas/dos type msdos (rw,sync,umask=002,gid=201)

The /nas/dos partition ownership and permission should now be correct and permission denied errors no longer reported after a successful file system extension.