how to grow a zfs file system

[pvaneynd]

I'm experimenting with zfs at home, for the moment on top of my md/lvm setup, and I ran out of disk space. Growing the lv is pretty easy:

frost:~# lvextend --size +110G /dev/new-vg/zfs-test
  Extending logical volume zfs-test to 120.00 GiB
  Logical volume zfs-test successfully resized
frost:~# zpool list
NAME       SIZE  ALLOC   FREE    CAP  DEDUP  HEALTH  ALTROOT
zfs-pool  9.94G  9.78G   161M    98%  1.00x  ONLINE  -

Hmm it did not notice the 110GB extra, so I did:

frost:~# zpool export zfs-pool
frost:~# zpool import zfs-pool
frost:~# zpool list
NAME       SIZE  ALLOC   FREE    CAP  DEDUP  HEALTH  ALTROOT
zfs-pool   120G  9.78G   110G     8%  1.00x  ONLINE  -

so simply doing an import/export is enough.

I'm looking at zfs to have a better idea of what btrfs will mean in the future for us.

Comments

[ideological_cuddle]

With "pure" ZFS it would've already had the entire disk, and you'd simply add additional disks to the pool as needed -- though with more than one disk to start you'd be using the ZFS RAID support.

It's been a fair while since I last looked at any btrfs info, but my understanding was that there's a bunch of stuff (and not just at the storage management level) that btrfs isn't supposed to do. So I'm not sure how useful ZFS is going to be as an example.

[cdybedahl]

Part of the thought behind ZFS was/is that it be _both_ the volume manager and the filesystem, so it can optimize across the entire stack. Running it on top of another volume manager won't let it do its intended job properly.

[reddragdiva]

+1

If you're going to ZFS, just ZFS.

[dagbrown]

Newer versions of zfs don't require the export/import step.

If you're running zfs-fuse, though, all bets are off. As far as I can tell, that's an abandoned project (well, the guy behind it is a student at a university, so he probably has bigger things to worry about).

If you're running the ZFS on Linux project, well, it only just developed a POSIX API to let it look like a proper filesystem, and it still fills your kernel logs with oopses. I doubt you'd learn anything useful about zfs from something which is so obviously still in development.

You really should be running zfs on raw disks, though, not on an LVM. It's supposed to take care of all of that for you, not just be a filesystem. And you should probably be running it in an operating system where it's properly supported, like FreeBSD or OpenIndiana (a fork of OpenSolaris).

[pvaneynd]

I'm using zfs-fuse at the moment.

I know that using zfs works better on FreeBSD or Solaris, but I fear that I'm just too used to Debian for some reason :).

I am considering using FreeBSD next time I have to reinstall my little server...