Local Storage

Local Sysdisk

After the PXE installation, the OS drive should be split into 5 partitions (with Ubuntu 18.04 LTS). The last partition corresponds to the additional storage not used for OS, swap or var, and should be mounted on /local_sysdisk. This is usually handled by the post-install script, under the function setup_local_automounts which updates the file /etc/fstab with the following line:

/dev/sda5 /local_sysdisk ext4    defaults        0 0

However, it can happend that the OS disk is given a different name than sda, in which case the system is left misconfigured and boot into emergency mode. In that case, the file /etc/fstab needs to be updated manually with the correct disk name (check with lsblk for example).

RAID array

If the machine is used as a scratch space, it should be configured with either a Hardware of Software RAID array.

Software RAID

After PXE install, you can check if the software RAID is recognized with cat /proc/mdstat or mdadm --detail. The softare RAID might be in auto-read-only mode by default after the first boot, in which case you need to run mdadm --readwrite /dev/mdX. Once you have an operational software RAID device /dev/mdX, you need to mount it under /local_scratch. To do so, add the following line to /etc/fstab if it is not there already:

/dev/mdX /local_scratch auto    defaults        0 0

Then you can mount it with mount -a.

Hardware RAID

You can check that an Hardware RAID device is present with lspci | grep -i raid. If so, check the name of the device with lshw -C disk (let’s say /dev/sdb), and add the following line to /etc/fstab:

/dev/sdb /local_scratch auto    defaults        0 0

You can repeat this process if there are several HW RAID arrays and mount the second one under /local_scratch2. Then you can mount it with mount -a.


On clear, the file /etc/fstab is a bit different

/dev/sdb        /local_scratch  xfs     inode64,nobarrier,noatime       0 0

Some optimization can be done in the choice of the filesystem and the mount options when creating a hardware RAID.