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Volume management

31 Dell EMC SC Series: Red Hat Enterprise Linux Best Practices | CML1031

• For the xfs file system, the filesystem check (fsck option) should be disabled in /etc/fstab because it

does not perform any check or repair automatically during boot time. The xfs journaling feature

ensures the file system integrity and data is in a consistent state after abrupt shutdown. If a manual

repair or check is necessary, use the xfs_repair utility to repair damaged file system.

• Set a value of 0 in the sixth field to disable fsck check. Here is an example of an xfs file system entry

in /etc/fstab:

UUID="b060087c-fba6-4517-a386-24dee0844f55" /testfs xfs defaults,discard

0 0

• For a filesystem on iSCSI volumes, use _netdev mount option (see section 2.4.5).

3.9.5 Expanding storage for the filesystem

Certain filesystem types, such as ext4 and xfs, support the online resize operation. The following outlines the

general steps to resize a filesystem online assuming non-partition LUNs are used.

1. Take manual snapshots of LUNs that are going to be expanded. If a filesystem spans across multiple

LUNs, make sure to take a consistent snapshot of all the LUNs in the same filesystem.

2. Expand the size of the existing LUNs in the DSM GUI.

3. Perform a SCSI scan on the host systems, refresh the partition table on each LUN path, and reload

multipath devices.

# rescan-scsi-bus.sh –resize

# echo 1 >> /sys/block/sdX/device/rescan

Reload the multipath devices:

# multipathd -k"resize map testvol"

For PowerPath, the new size is automatically updated.

4. Expand the physical volume and logical volume if the file system is on top of LVM.

# pvresize /dev/mapper/testvol

# lvresize –L $NEW_SIZE_in_MB /dev/vgapp/lvapp

5. Extend the filesystem size to the maximum size, automatically and online.

# xfs_growfs –d /testfs #For xfs

# resize2fs /dev/mapper/vgapp-lvapp #For ext4

Note: As with any partition or filesystem operation, there is some risk of data loss. Dell EMC recommends

capturing a snapshot of the volume and ensuring good backups exist prior to executing the steps.

3.10 Removing volumes

The Linux OS stores information about each volume presented to it. Even if a volume is in an unmapped state

on SC Series storage, the Linux OS will retain information about that volume until the next reboot. If the Linux

OS is presented with a volume from the same target using the same LUN ID prior to any reboot, it will reuse

the old data about that volume. This may result in complications, misinformation and mismanagement of the