v28 zpool on FreeNAS 9.2.1.6

[iSCSIinitiator]

Question:

What, if any, are the stability concerns with running a v28 zpool on FreeNAS 9.2.1.6?


Background

I've been running multiple FreeNAS servers for a couple of months now, all with v5000 zpools and all now at FreeNAS 9.2.1.6. I've followed the (very helpful) advice in the forum here and am trying to do all the right things (plenty of ECC RAM, periodic scrubs, etc.). Things are going well so far.

I'm about to set up a new multi-server FreeNAS system which for me will be The Big One - storing lots of important data and acting as a domain controller. The system will be multi-server, as I'll be replicating and rsyncing data to a twin config in another location and a siloed (likely Linux XFS) fail-safe, respectively.

I really want to do everything I can to protect my data and facilitate recovery, should it be necessary. I know I want 9.2.1.6 because the SAMBA 4 DC stuff is critical. However, I also understand that FreeNAS is ahead of many other distributions in its zpool v5000 code base (e.g., hole_birth) and SAMBA 4 integration (e.g., better Windows ACL support) - some of the many reasons I love FreeNAS.

Because of all these factors, I'm contemplating creating a v28 zpool with FreeNAS 8.3.2 and immediately detaching the zpool. Then, on a clean install of FreeNAS 9.2.1.6, I'd auto-import the zpool (but not upgrade it) and then move forward from there.

I've already tried some basic tests with this, and FreeNAS 9.2.1.6 seemed to work with the v28 zpool, and I could even detach the zpool and move the disks back to an 8.3.2 system and auto-import it. I would never want to do this on a production system unless there was a major issue or I was performing a planned upgrade, but I really like the idea that the data/disks would be interoperable with other distributions if I needed them for recovery, etc. While my other servers run RAIDZ2, I'm planning to set up the twin FreeNAS boxes here each with zpools striped across vdevs with 4-way mirrors for increased redundancy and flexibility.

I understand that v5000 zpools have lz4 and other features that I would forfeit using v28, but I don't need these other features, as far as I know. What I'm really concerned about, though, is FreeNAS 9.2.1.6's comfort and stability with a v28 zpool. If replication from a 9.2.1.6 system with a v28 pool to another 9.2.1.6 system with a v28 pool is dangerous, or if Windows ACLs break on a v28 pool, those sorts of things would be dealbreakers for me.

Any thoughts or suggestions would be greatly appreciated.

Thanks very much.

 

[DrKK]

Just a couple days ago, Cyberjock and I were talking about a similar question. His claim was that there was possibly (he wasn't sure) some functionality concerns with 9.2.1.6 with older ZFS versions. We didn't talk much about it, because I was maximally up-to-date for my particular version, and therefore it wasn't a concern for me as I upgraded to 9.2.1.6. But he (Cyberjock) is on an older ZFS version, he DOES NOT want to upgrade necessarily (although I think he's going to), so he was personally concerned about it.

Hopefully he'll weigh in and can refresh us as to what his concerns were.

 

[iSCSIinitiator]

DrKK,

Thanks for the information. Yes, I'm hoping the title will be clickbait for Cyberjock, as I'd appreciate his input.

Also, though, if anyone else has tried this or has knowledge about why it might not be a good idea, that would be really helpful. I'm worried about things like if the development roadmap for FreeNAS 9.3 or future versions indicates that v5000 pools will be required?

Best

 

[DrKK]

I think @cyberjock reads every post. I don't think clickbait is necessary. Unless the post is from someone he has mentally hell-banned.

 

[Ericloewe]

As of a few minutes ago, the roadmap made no mention of any limitations regarding pool versions - if anything, I can imagine support for the creation of older pool versions being added.

What can happen is some new, exciting feature not being available due to it requiring certain features of newer zpools - can't really think of anything, tough.

 

[cyberjock]

Ok, so I'm on v28 as I chose to stay on v28 versus v5000. v5000 is a mess because every other OS out there has a different timetable for releasing feature flags. Staying on FreeNAS and up-to-date means having the latest feature flags. It's great news for those in corporate environments that buy a TrueNAS server for maximum performance and features as there's no risk of them wanting to run to some other OS that won't support the feature flags. But, for home users that *may* want to move to ZFS on Linux or some other OS this could be a problem.

I am on v28 because at the time I wanted the open opportunity to move to ZFS on linux. The problem I'm seeing is the ZFS on linux project is having a serious problem with keeping up with new feature flags that are being developed. One flag FreeNAS has had for 8 months and ZFS on linux isn't even testing it yet. Code was generated but it keeps being pushed back due to other committments and such.

I do plan to upgrade to 9.2.1.6 but I've been so busy with life stuff I haven't had a chance to do it. When I do I will probably upgrade to v5000 as there's no reason for me to stay on v28 anymore.

There are *some* concerns that not keeping up to date could cause some bug that is fixed in the v5000 code to be left unfixed in the v28 code, and this *could* cause problems. There are no solid cases of this, but it is at least conceivable. So staying on the latest code is probably a good idea.

Hope this clears everything up.

 

[iSCSIinitiator]

Cyberjock,

Thanks very much for the info, very helpful as always. One quick follow-up, if you don't mind sharing:

Have you had any experience testing/running a v28 zpool with a FreeNAS 9.X release?

(You mentioned that you're running a v28 zpool and that you haven't upgraded to 9.2.1.6, but I was wondering if you have been using an earlier 9.X release or if you've stuck with FreeNAS 8.)

Thanks again.

 

[cyberjock]

I'm on 9.2.0 and had no problems.

 

[DrKK]

I haven't upgraded my ZFS version from what was on 9.2.0.

I just want to make sure 9.2.1.6 isn't a lemon for me before I do that. lol

 

[titan_rw]

Sorry for the reply to a week old post.

One of my pools is still v28 with freenas being 9.2.0. I guess at some point I'll have to upgrade it. Could probably do it now, as I'm pretty confident now that I'll not need to revert back to 8.3.x, which was the original reason for not upgrading the pool. Never thought about ramifications of using an older pool version on newer freenas's.