Extend Data Volume after RAID Increase

[Matt Blasco]

I currently have two 2TB disks in a RAID1 on a perc H700 controller. I need to add more storage space for VMs, and am deciding between creating a second virtual disk on the H700 (RAID1, two 2TB disks, same as the other) or migrating the current RAID1 to a RAID5 with a total of four 2TB disks.

The latter option would yield a 3x increase in my storage capacity, whereas the former would only yield a 2x increase, so I am leaning towards the RAID1 to RAID5 migration.

If I proceed with the RAID1 to RAID5 migration, how will I need to go about making this additional capacity available to ProxMox such that the "local" storage (mounted at /var/lib/vz) has a total capacity of 6TB rather than the current 2TB?

Thanks in advance for your input.

 

[LnxBil]

Does your controller have the ability to online migrate a two disk raid 1 to a four disk raid 5? I personally do not know any controller of that kind.

Normally, you do a backup, rebuild raid and restore with an offline time of a couple of days.

Easiest thing would be to create another raid and expand the volume group (if LVM) and increase your data volume.

 

[Matt Blasco]

According to this page, the migration is possible specifically from a RAID1 with 2 disks to a RAID5 with 3 or more disks.

I had considered your alternative as well, and that would work fine, but it would also leave me with a new capacity of 4TB as opposed to 6TB.

 

[LnxBil]

I had considered your alternative as well, and that would work fine, but it would also leave me with a new capacity of 4TB as opposed to 6TB.

Yes, but you'll have more write speed. You did not describe your workload, but I'd never use RAID 5 on a system with a huge IO load, e.g. a frequently written database. For NAS appliances and data graveyards, this works, but not for more demanding tasks.