ZFS pool upgrade

TrueNAS General
1

Hi all.

I haven’t updated ZFS yet after upgrading to 24.10 from 24.04, because I wanted to maintain compatibility with the previous version in case of problems. Do you think I can still avoid upgrading ZFS to move to 25.04, or do I have to at least update ZFS to version 24.10 before moving to it?

Thanks in advance.

2

New versions, 25.04, can work with previous versions fine. You would only need to upgrade your pool if you needed new features, like Raid-Z expansion, if your current pool didn’t have them enabled.

3

One rule of thumb that I use, is not to upgrade the ZFS pool version until all my boot environments support all the features. Meaning a new ZFS pool feature that just came out, won’t be supported by old TrueNAS versions. So if you upgrade pool version, you are now 100% committed to using that new TrueNAS version. No easy way of going back.

This can mean upgrading just 1 or 2 features at a time, from the command line. With those features selected because they are usable by all your installed boot environments, (aka older TrueNAS versions). Harder yes, but much, much safer in case you want to roll back TrueNAS versions, (even temporarily).

Last, never upgrade the pool version on the boot-pool. This needs to be using a common feature set that Grub can understand. Further, their are extremely few reasons why a boot-pool would want a pool upgrade.

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4

Thank you. I don’t know commands to upgrade single features, I will look into this. If I upgrade from WebUI, I think it’s only involved zpool, not boot-pool, correct?

5

Yes, you have the “upgrade” button for each zpool in the webui. As far as I know there is no “upgrade” button for the boot-pool in the webui.

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6

Also, when upgrading from the WebUI / GUI, it does everything. Not generally what people what.

The individual features are enabled from the command line. Something like this:

zpool set feature@raidz_expansion=enabled POOL_NAME

To get the list of features, and their status:

zpool get all POOL_NAME | grep feature

Last, to get a brief over-view of each feature, bring up the manual page and search for the feature;

man zpool-features

That brief description may not be enough for a new ZFS user to determine if they want that feature. However, if you don’t know what the feature is, then you likely don’t “need” it. Or at least not right away.

The more important features are already enabled.

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7

Thank you, very useful!