Can you extend a RAID-Z volume?

[Evelen]

Hi.

Lets say I start with RAID-Z1 with 3 4TB drives, 1 parity disk and two normal disk for a total 8TB capacity
Can I later add an extra drive and "upgrade" to RAID-Z2 with same capacity, or extend the RAID-Z1 to 12TB capacity?

I have read this was not possible before, but is it any changes in that the last time?

 

[anmnz]

In brief -- this is not possible and is very unlikely ever to be possible.

 

[danb35]

this is not possible

Correct

very unlikely ever to be possible.

Disagree here; the project isn't dead and with Matt behind it, it seems likely to be released--though it's far from clear when that would be.

1 parity disk and two normal disk

RAIDZ doesn't work that way (nor does any other modern RAID AFAIK)--parity is striped through the vdev. RAIDZ1 will use (approximately) one disk's worth of parity, but there is no dedicated parity disk.

 

[Evelen]

Okey, how are you suggesting I build up my storage? I can't go out buying 10 drives at the time.

 

[danb35]

I don't know where you get the "10 drives" figure; the configurations you'll most often see recommended here are:

• Mirrors, in which case you can expand the pool by adding a pair of disks at a time; or
• RAIDZ2 in vdevs of 6-8 disks.

A vdev of 10 disks is do-able, but about the largest you'd want to set up.

 

[sretalla]

Okey, how are you suggesting I build up my storage? I can't go out buying 10 drives at the time.

Maybe ZFS (and FreeNAS, which exclusively uses it) isn't the product for you (at least for now).

You could try Open Xpenology, which I think gives you RAID expandability (it's the open-source version of Synology).