Help to move from a mirror to raidZ1

zippy1

Dabbler
Joined
Apr 4, 2016
Messages
13
I am running out of space on my existing FreeNAS server this is setup with:
  • 1a) 3TB (mirror 1a&1b) data
  • 1b) 3TB (mirror 1a&1b) data
  • 1c) 1TB (mirror 1c&1d)Time Machine.
  • 1d) 1TB (mirror 1c&1d)Time Machine.
I then have a second backup FreeNAS server (this is automatically backed up to via rsync):
  • 2a) 3TB (mirror 2a&2b)
  • 2b) 3TB (mirror 2a&2b))
  • 2c) 1TB for a second Time Machine drive.

I am running out of space as only basically have 3TB storage. So I have bought a new 3TB drive and am looking to be able to swap the 1a & 1b mirror to be part of a raidz1 with the additional drive. Whats the best way to do this I was thinking about taking one of the drives say 2b and 1b from each mirror and then setup a new pool with 1b, 2b and the new drive.

Copy from 1a to the need raidz1 pool and then once finished remove 1a and put this back into server 2 and then get another drive and then copy from server 1-2?

Keen to know everyones thoughts and if this is this even possible? especially as I am sure server 1 will still 1b is part of the original mirror and not allow me to add it into a new pool? I was trying to keep at least part of one together as I assume it will be faster to copy on the same server than over LAN?
 

no_connection

Patron
Joined
Dec 15, 2013
Messages
480
With relatively small amount of data I don't see why you need to spread the load out to 3 drives (Z1 with 3 3TB drives right?) compared to just swap out each drive with 8TB for example.
I get the cost appeal part of it, pretty much doubling storage by just buying another 3TB drive, but it also lock you into that since you can't do much more to a Z1. Also the last slot is kinda on it's own since you can't add that to the Z1.
If you meant 4 3TB drive Z1 then space gain is real compared to mirror but I doubt there is a way to cli that with no risk.
 

zippy1

Dabbler
Joined
Apr 4, 2016
Messages
13
Thanks for your reply but 3x8TB is £659.85 so quite a bit more and the backup would also need to be upgraded to match or would be useless... so £1,319.70 is quite a cost difference and then I would also have 4 x 3TB drives just sat there doing nothing.
 

Yorick

Wizard
Joined
Nov 4, 2018
Messages
1,912
Yup, I'd say take 2b, 1b, plus the new drive, build a raidz1 and move data from 1a over. Presumably you won't lose 1a and 2a at the same time. When that's done and you've confirmed that the data is in, blow away the pool that's on 1a, use 1a to put a mirror back on 2a. Eventually, you can destroy that pool as well and recreate as a raidz1, if you want the additional space for backup.

Side note: Used 3TB SAS drives go for 25 bucks (!) on eBay. For backup purposes, they'll work great. See the recent post about that in off-topic.
 

no_connection

Patron
Joined
Dec 15, 2013
Messages
480
You would be replacing the two 3TB drives (1a 1b)with two larger, 8TB was an example. Then move those to backup server and do whatever configuration you want. Or move them to 1c1d. Or remove 1c1d and add a mirror of 2x3TB to main pool.

You are looking at a 50% current space efficiency compared to 66% or 75%
With 3drive Z1 you are getting 66% but are wasting one drive bay to no redundancy. IMO that is not a lot more space.

And with a 4drive Z1 I highly doubt you can make that from GUI with other drives still in it.

That is my thoughts on it.
 

KrisBee

Wizard
Joined
Mar 20, 2017
Messages
1,288
@jacklawry I've just seen your post and I'm liitle suprised no one has mentioned the "RAIDZ1 is not recommended for drives over 1 TiB in size" warning. For servers limited to 4 HDDs that leaves either 4 in a raidz2 or a pool of two mirror vdevs, both with the same 50% storage efficiency. Apart from avoiding the "2 drives fail in a single mirrorr VDEV and all of the data in your entire pool is lost" situation, I wonder why you decided on two pools, each with a single mirror vdev. You could have had a single pool of 2x3TB + 2x1TB with appropriate datasets and quota/reservations as necessary. You only need two larger HDDs to grow the overal pool size by changing one of the mirrors, as opposed to having to change all disks in a raidz pool.

This boils down to what @no_connection has already said. I'd plan purchases to use two mirror vdevs in a single pool on the HP gen9 server. Possibly raidz2 on the HP gen 8.
 
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