ZFS with Offsite rotation

[rcrampton]

I'm sure this has been answered somewhere but I'm not managing to find it.

I currently use rsync and mirror across 3 drives, rotating 1 of the 3 off-site.
To expand storage I set up another 3 disks in a separate mirror.

I'd like to move to ZFS to take advantage of snapshots and protection from bit rot and want to maintain the practice of rotating a disk off-site.

This is a home server where I value data integrity and capacity over speed.

I'm thinking of a 3 disk raid5 on-site with a 4th disk off-site that I rotate monthly'ish.

I believe that's safe from bit rot and has snapshots on-site. My off-site would not have snapshots and could independently bit rot between syncs but I can live with that.

Specifically I'll have 3x 1.8TB disks in raid5 with a 3TB disk rotating off-site.

To expand the pool later I'll auto-expand by swapping out for larger disks one by one.

 

[cyberjock]

If you value data integrity over capacity you should do RAIDZ2. RAIDZ1 is "dead"(link in my sig if you want an explanation).

I'm really confused as to your method of backup without snapshots. ZFS's best backup strategy is snapshots and replication. It's ultra fast and part of ZFS' design.

There's nothing stopping you from using rsync or even just a plain old 'cp' but why do that when snapshots are pretty much perfect for your needs!

 

[rcrampton]

Thanks for the reply. I should replicate snapshots to the backup disk it sounds like?

Also thanks for the information behind raid5 and raid6. The $100 I save by having a 3 disk raid5 over a 4 disk raid6 really isn't something I'll worry about. On the other hand I'm not overly worried about losing a sector every few years during a rebuild and losing a song or a pic. I think I'm happy if I prevent the ongoing systemic bit rot problem. You've got me re-thinking that a little. I don't know what the statistics are of losing a bunch of data, say if I lost 50 songs or 50 pics. I'll pay $100 for an extra drive to cover that, easy decision.

 

[cyberjock]

Well, people don't generally lose a song or a pict. They lose the whole damn pool. And I mean ALL data in the pool is gone. The forum is FULL of examples of lost pools. Why do you think I've put it in my sig so it's in 9000+ places on the forum?

I'm chatting with someone in IRC right now that had a RAIDZ1 of 4 disks and can't mount it because 1 disk failed and the pool won't mount.... he said he's almost in tears because of the family pictures and whatnot that aren't backed up...

 

[rcrampton]

Thanks for the info in your signature.

This isn't as easy as "I'm running ufs and think I'll just move to ZFS". That's what I was thinking and it looks like an unmitigated disaster in the making. Based on what I'm reading in the forums I think there are a lot of boxes like that out there.

ZFS doesn't really look well suited to the typical home user. You need to do some serious reading and understanding of the details to go this route.

I've got an Asus AT5NM10T-I that doesn't support-ECC RAM.

 

[cyberjock]

Thanks for the info in your signature.

This isn't as easy as "I'm running ufs and think I'll just move to ZFS". That's what I was thinking and it looks like an unmitigated disaster in the making. Based on what I'm reading in the forums I think there are a lot of boxes like that out there.

Oh yeah.. there's SO many disasters that are just waiting to happen. Why do you think I do the consultation work. I don't make very much money on it, but I do appreciate that people want to go to ZFS and I'd rather they not learn what not to do the hard way.

ZFS doesn't really look well suited to the typical home user. You need to do some serious reading and understanding of the details to go this route.

Your observation is 100% correct. ZFS was never designed for home users. It's an engineering feat that has relatively high system requirements and a deep understand of the stuff under the hood is required to avoid making fatal mistakes. I'm not the least bit surprised by Apple removing ZFS from their OS after announcing it would be included. As far as I'm concerned(and there's a little evidence of this) is that Apple started playing with ZFS and realized that their userbase is incapable of making smart decisions with ZFS. So they made the responsible choice for their business and abandoned ZFS.

I've got an Asus AT5NM10T-I that doesn't support-ECC RAM.

Yeah.. and as you no doubt know, you are already off to a bad start with that hardware. :(

 

[rcrampton]

Seriously, thanks for your help. This feels a little like narrowly being missed by a speeding car as you walk across the street :)