FreeNAS replication

Forums › Self-hosted › FreeNAS replication

lyndondrake

236 posts

Master Geek

ID Verified

#127053 28-Jul-2013 17:19

Hi,

I've setup a FreeNAS box recently, partly for the fun of doing a project but also to get a decent backup system in place.

I managed to pick up an HP N40L in PB Tech's sale a few weeks ago, put 4x2TB drives in, and found FreeNAS surprisingly easy to get up and running with a ZFS RAIDZ2 pool (so hopefully can lose 2 drives before I lose data). The firmware's been flashed so I can do hotswaps of the drives (tested this before putting any data on it). Now it's acting as a TimeMachine target, as well as storage for my Mac Mini server and I've archived a bunch of stuff off my laptop. The only extra hardware I'm planning to drop in is an HP P410 card with FBWC in JBOD mode to reduce the possibility of write corruption.

The next step is getting offsite backup going. To that end I'm currently ZFS replicating onto an external drive which I take into work, but I'm thinking about setting up a cheaper FreeNAS box somewhere else and replicating to that. With Snap VDSL I shouldn't hit bandwidth usage issues if I time the snapshot replication to run in the early hours of the morning, and in any case provided I do the first snapshot locally then the incremental snapshots shouldn't be too large.

Has anyone else tried something similar?

Lyndon

chevrolux

4962 posts

Uber Geek
Inactive user

#868289 30-Jul-2013 08:24

How much data allowance do you have?

I would have thought the easy way to do it would have the remote box VPN in to your home network and then just use rsync to copy the dirves across.
The initial backup will be immense but you could do that locally and then take the remote box offsite.

I think the latest version of FreeNAS has OpenVPN built in so as long as you have a decent router with OpenVPN server on it you are happy as.

lyndondrake

236 posts

Master Geek

ID Verified

#868308 30-Jul-2013 08:46

Yep, local seed of the replication is definitely the way forward. The reason I was thinking of ZFS replication is that rsync only does file-level changes (& e.g. the TimeMachine images are opaque to rsync), whereas ZFS can do some degree of block-level diff, I think. Even with that the data allowance might be the killer, but I was planning to use Snap's early hours of the morning option.

The VPN thing is something I'd probably do at the router level, as then I can avoid the CPU load of an encrypted SSH tunnel and either use direct rsync, or zfs + netcat.

Ragnor

8223 posts

Uber Geek

Trusted

#869857 1-Aug-2013 12:04

What you want to do should work really well, that's what ZFS replication was designed for. Haven't tried it myself though.

PANiCnz

990 posts

Ultimate Geek

#870223 1-Aug-2013 19:10

Isn't the need for "HP P410 card with FBWC in JBOD mode" redundant with ZFS? Seems a waste of money to me.

lyndondrake

236 posts

Master Geek

ID Verified

#870228 1-Aug-2013 19:14

Apparently it's not. ZFS does all the redundancy, but what it can't do is guarantee writes if there's an untimely power failure. Sod's law, I've already had one power failure in the middle of transferring data. The problem is that it's (possibly) silent corruption at that point. Similar thing with putting ECC RAM in. After I'd read a fair bit about it, I decided that given this is meant to be a reasonably serious effort to preserve my data, it was worth the extra expense.

A cheaper alternative is a UPS, albeit a couple of steps further away on the hardware chain from where you actually need to guarantee the writes.

Plus it's kind of fun. Expensive fun, but still fun.

jpoc

1043 posts

Uber Geek

#871189 3-Aug-2013 13:09

PANiCnz: Isn't the need for "HP P410 card with FBWC in JBOD mode" redundant with ZFS? Seems a waste of money to me.

I think that you are correct. ZFS specificly avoids the Raid 5 write hole which is what can give Raid 5 users silent data corruption in the event of a power fail during write. It may actually be worse than redundant because the ZFS documentation is full of warnings about the effects of putting things like that in between ZFS and the underlying storage.

I have a fair amount of experience of ZFS on Free-BSD on several servers. All with nothing other than dumb controllers between ZFS and the drives and I have never had any problems even when a faulty fusebox gave me multiple power disconnects.