The ME5 storage system supports a wide range of Linux file systems. This section focuses on two popular and stable file systems: ext4 and xfs.
File system layout
The file system can be created on top of a LUN, a LUN partition, or a logical volume within LVM. If the file systems reside in LVM, follow the LVM guidelines when creating and grouping multiple file systems.
File system mount options
When mounting a file system, consider the following options and guidelines:
- Create the file system with the mkfs command.
# mkfs.xfs /dev/mapper/vgapp-lvapp
- Identify the file system by its UUID or LVM LV device in the /etc/fstab file. Avoid using any non-persistent device paths such as /dev/sd*.
- UUID can be queried by the blkid command.
# blkid /dev/mapper/vgapp-lvapp
/dev/mapper/vgapp-lvapp: UUID="77d5cb05-12d0-4005-869a-ba641a6b35ee" BLOCK_SIZE="4096" TYPE="xfs"
- Include nofail in the mount option if the Linux operating system experiences a mount issue during system boot. This prevents interruptions during the boot process which would require manual intervention.
- For the xfs file system, the file system 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 file system integrity and that data is in a consistent state after abrupt shutdown. If a manual repair or check is necessary, use the xfs_repair utility to repair a damaged file system.
- To disable fsck check, set a value of 0 in the sixth field for the file system entry in /etc/fstab. Here is an example of an xfs file system entry in /etc/fstab:
UUID="77d5cb05-12d0-4005-869a-ba641a6b35ee" /app-data xfs defaults,discard,nofail 0 0
Certain file system types, such as ext4 and xfs, support the online resize operation. The following procedure outlines the general steps to resize a file system online assuming that non-partition LUNs are used.
- Expand the size of existing volumes in PowerVault Manager. Click Provisioning > Volumes > Volumes table. Select a volume and choose Expand Volume from the action drop-down menu. Enter the extended size in the next Expand Volume window.
Figure 14. Expand Volume in PowerVault Manager
- Perform a SCSI scan on the Linux host, refresh the partition table on each LUN path, and reload multipath devices.
# rescan-scsi-bus.sh --resize
- Reload the multipath devices. Skip this step if multipath devices are disabled.
# multipathd -k"resize map mpathb"
- Expand the LVM physical volume. Skip this step if the file system does not reside in LVM.
# pvresize /dev/mapper/mpathb
- Expand the LVM logical volume. Skip this step if the file system does not reside in LVM.
# lvresize –L $NEW_SIZE /dev/vgapp/lvapp
- Extend the file system size to the maximum size while it is mounted.
xfs
# xfs_growfs –d /app-data
ext4
# resize2fs /dev/mapper/mpathb