Adding Drive to RAIDZ2 Pool

[BigPapaPSP]

I have been using FreeNas a few months with much success. I have a single RAIDZ2 pool consisting of 4 drives -- All identical 10TB drives. I am running low on space, and want to expand or extend this pool..

My server has 6 hotswap bays and four of the six occupy my existing 4-drive RAIDZ2 pool. I thought I could add a 5th 10TB identical drive and add it to that RAIDZ2 pool that already exists. Is this NOT the case? The last thing I want is to add this drive and for it to show up as a single striped drive and not part of the redundancy of my RAIDZ2.

I looks like any of these steps are irreversible -- So....I figured I better post this for confirmation of what my options are.

Thanks in advance.

Dj

 

[BigPapaPSP]

Further info... about 6 months ago I was exploring FreeNas and I set up a server with a pool of 4TB drives. But when I tried to do this exact same thing, They were added as striped drives and didn't appear to be part of my RaidZ2 drive cluster/array -- but existed outside of the RAIDZ2 as a non-redundent striped drive. And with no option available to change it from striped drive into part of the RAIDZ2 -- I abandoned the setup... Rebuilt the machine on new hardware (which was the plan anyway) and increased my drives to 10tb instead of the 4tb drives -- and started my current server with the 4 drives (10TB each). So, I'm a bit gun shy... This is no longer a test system -- it's my production server at this point. SO want to be very clear what my options are.

Thanks for any advise, assistance, solutions....

Dj

 

[Basil Hendroff]

You won't be able to extend the existing vdev, but you can extend the pool by adding a second vdev (mirrored disks for redundancy). Further details can be found in https://forums.freenas.org/index.ph...ning-vdev-zpool-zil-and-l2arc-for-noobs.7775/

 

[PhiloEpisteme]

So, I'm a bit gun shy... This is no longer a test system -- it's my production server at this point. SO want to be very clear what my options are.

Keep backups :). They go a long way to ensuring you don't accidentally lose any data. @Seymour Butt is correct though, with your current hardware you will not be able to increase the size of that vdev. In general, you have 3 options to increase the size of a pool consisting of a single vdev.

1. Add a second vdev. This vdev can use any sort of striping, mirroring etc that you wish and can use any number of drives.
2. Replace each drive, one by one, in your current vdev with a larger disk. Once every drive in the vdev has been replaced, and not before, with a larger disk your new vdev will have expanded capacity and thus your pool will have extended capacity.
3. Backup your data and destroy the pool and rebuild it using a vdev with more drives, larger drives, or both. Do note that this is not expanding your pool but instead is destroying it and remaking it with more capacity.

A couple of key points you'll want to pay special attention to as you learn more about FreeNAS: A pool is made of vdevs. vdevs are made of disks. You can add new vdevs to a pool. You can increase the size of a vdev by increasing the size of every disk in the vdev. If you lose a vdev in a pool you will lose the pool. No level of disk parity is a replacement for backups.

 

[BigPapaPSP]

Keep backups :). They go a long way to ensuring you don't accidentally lose any data.

Yeah, backups are a great concept... but how does one backup 40TB??? Floppies??? :) This server is a dual node rack mount SuperServer. I will re-do the FreeNas build that is idle on the 2nd node... and build an vdev with 6 drives from the start...

Thanks for the help....

 

[PhiloEpisteme]

Yeah, backups are a great concept... but how does one backup 40TB???

Many large drives :) I recently purchased 8x8TB drives for my backup drives. Some folks use cloud backup solutions but you'll have to do some research to figure out if that is a solution that will work for you.

 

[Basil Hendroff]

@BigPapaPSP A redundant disk array is not a substitute for backups. There seems to be a widespread misconception that if you have implemented some form of RAID, you don't need backups. You will be devastated if you lose your 40TB pool. You will regret not having taken a backup of your data.

At the very least, regularly snapshot your data onto 4 x 10TB external drives (manually intensive). Ideally, invest in snapshotting and replication of your data to a second server (a fully automated solution).

 

[Basil Hendroff]

NB: Snapshots and replication is functionality that is built into FreeNAS. All the details are in the FreeNAS User Guide