Is it safe to upgrade ZFS features on the boot pool?

[Samuel Tai]

When I run zpool status -v freenas-boot, I get:

Code:

  pool: freenas-boot
 state: ONLINE
status: Some supported features are not enabled on the pool. The pool can
        still be used, but some features are unavailable.
action: Enable all features using 'zpool upgrade'. Once this is done,
        the pool may no longer be accessible by software that does not support
        the features. See zpool-features(5) for details.
  scan: scrub repaired 0B in 00:00:16 with 0 errors on Wed Feb 10 03:45:16 2021
config:

        NAME                                          STATE     READ WRITE CKSUM
        freenas-boot                                  ONLINE       0     0     0
          gptid/17ae8771-4601-11e9-bf36-d0509901339e  ONLINE       0     0     0

errors: No known data errors

Has anyone upgraded their boot pool via zpool upgrade? Are there any ill effects afterwards?

 

[joeschmuck]

You know, I have never contemplated upgrading the ZFS on a boot pool before. For me it's one of those things, if it works, don't break it. But from a scientific perspective I can see why the question is asked. Sounds like something that should be tested.

 

[Patrick M. Hausen]

Has anyone upgraded their boot pool via zpool upgrade? Are there any ill effects afterwards?

I do that all the time - after a couple of days of testing when I am confident I do not need to roll back the last update. Which is precisely the downside: you cannot boot an older release, anymore.

 

[sretalla]

I recall seeing a comment from iX to not do it... let me see if I can find it.

Well... proof my memory isn't perfect, but it is from a couple of very experienced forum members:

Boot ZFS pool upgrade

I see this in my status reports: ########## ZPool status report for freenas-boot ########## pool: freenas-boot state: ONLINE status: Some supported features are not enabled on the pool. The pool can still be used, but some features are unavailable. action: Enable all features using 'zpool...

www.truenas.com

 

[Kris Moore]

No, please do not upgrade features on the boot pool. They do not improve anything, and if the boot-loader doesn't like it, you could end up bricking your installation.

 

[Patrick M. Hausen]

@Kris Moore You don't update the boot loader?

 

[Kris Moore]

We do, but the issue is that boot-loaders tend to lag behind ZFS in terms of what feature flags it supports. So if you upgrade the boot pool to a flag which hasn't landed in the loader yet, you could render it unbootable. (Same goes for Grub and BSD loaders)

We also don't make any use of the newer features for boot-pools, so there's no real benefit today in zpool upgrade there, apart from getting rid of the notice.

 

[Patrick M. Hausen]

Understood, but still slightly puzzled. I never had a FreeBSD system where the boot loader and ZFS were out of sync. zpool upgrade specifically reminds you to reinstall the boot loader. But OK. Noted ...

 

[Kris Moore]

Understood, but still slightly puzzled. I never had a FreeBSD system where the boot loader and ZFS were out of sync. zpool upgrade specifically reminds you to reinstall the boot loader. But OK. Noted ...

That maybe was true when only using the ZFS that was merged in FreeBSD, but in TrueNAS 12 we are building OpenZFS as an out-of-tree kernel module, which means we can bring features / updates in a bit more rapidly. That plus, if you roll back some old BE could try re-stamping an older version of a loader during an upgrade. So best to not touch it, unless you are very comfortable at the command-line and boot-loaders in general. ;)

 

[Patrick M. Hausen]

So best to not touch it, unless you are very comfortable at the command-line and boot-loaders in general.

I am. I know Forth Probably will have to learn some basic Lua, eventually.

 

[Kris Moore]

I am. I know Forth Probably will have to learn some basic Lua, eventually.

Lol, its not often that I run across another poor soul that knows Forth as well. I did just enough to be dangerous, and I'd prefer to never touch it again :)

 

[Adrian]

I implemented Forth for a Sharp MZ80K (a bit like the original Pet but Z80 based). I spent more time saving and verifying duplicate copies of the source to cassette tape than doing anything useful. I contributed it to a free software library after being beaten to the punch by somebody else with a commercial version. It was the hassle with tapes which drove me to buy an Osborne 1, and thankfully put Forth behind me. I have never been tempted back to it.