# Safe to upgrade ZFS?



## Migelo (Oct 16, 2013)

Hi!

With the release of FreeBSD 9.2 ZFS has also been upgraded. Is it safe to upgrade it by running `zpool upgrade`? I'm just a bit paranoid if it can somehow make my pool unreadable.

Thanks!


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## Sylhouette (Oct 17, 2013)

It should work without a hassle. But before you do, make a backup, just in case. So if things go wrong, you have a backup of your data.

I have done it on most of my servers, four to be precise and I have had no issues at all. But that does not guarantee that it will go ok on your configuration.

gr
Johan


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## ShelLuser (Oct 17, 2013)

No problem.

Keep in mind that a lot of ZFS pool upgrades are merely checks to see if the filesystem is healthy after which the version number gets changed. And that version number is then used as a means of identification by the ZFS userland programs. And that will enable certain features.

You can get a good overview of these features by using `$ zfs upgrade -v`.

In this case you're looking at LZ4 compression and ZFS TRIM. I've had some issues with TRIM on my VPS environments, so if you want to make sure that your system does not start utilizing TRIM right away then be sure to add this to your /boot/loader.conf:


```
vfs.zfs.trim.enabled=0
```


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## Migelo (Oct 18, 2013)

Thanks to both of you.

Regarding TRIM, I actually don't have any SSDs in my pool, so turning it off by modifying /boot/loader.conf would not make any difference. But I'll enjoy the additional encryption.


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## Migelo (Oct 20, 2013)

Ok, I issued `zpool upgrade tank` and it worked without any hiccups.

Thank you for the assistance.


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