Scenario: You have an existing RAID array in OMV and you have replaced each drive one at a time with a larger drive. Now you wish to grow the array into the larger size but it turns out the GUI of OMV does not have that option. When you navigate to “RAID Management” and then click “Grow,” it comes up with an empty list of devices. This is expected since all of your drives are used in the array already.

To grow the array into the new larger size after all drives have been upgraded, access the console of OMV (e.g., via SSH) and issue the command:

where the letter X represents the number of your md device. The first md device is typically zero (i.e., md0).

After issuing the command, you should receive a confirmation immediately that the array has been resized. Something like this for an md0 device:

mdadm: component size of /dev/md0 has been set to [the new size in K]

You can confirm the change has taken place by navigating back to RAID Management where you will then see the RAID is in a resync process.