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Tim Thomas's Blog
Creating ZFS File Systems from a ZFS Pool
In a previous blog entry I gave a couple of examples of how to create one big ZFS pool on all of the disks in a Sun Fire X4500. The ZFS pool was called bigpool and the mount point defaulted to /bigpool.
You could just store files in the /bigpool, but what you might want to do next is create more ZFS file systems out of the pool for various purposes.
I can easily create a new file system out of bigpool as follows:
root# zfs create bigpool/mynewfs
root# zfs list bigpool/mynewfs
NAME USED AVAIL REFER MOUNTPOINT
bigpool/mynewfs 24.5K 4.81T 24.5K /bigpool/mynewfs
The mount point defaults to /bigpool/mynewfs..let's say that I don't like that; in this case I don't have any data in the new file system so I can destroy it and start again...
root# cd bigpool/mynewfs
root# zfs destroy bigpool/mynewfs
cannot unmount '/bigpool/mynewfs': Device busy
I did this just to see what happened: OK, I proved that I cannot delete a busy file system...now...try again...
root# cd /
root# zfs destroy bigpool/mynewfs
root# zfs create -o mountpoint=/mynewfs bigpool/mynewfs
root# zfs list bigpool/mynewfs
NAME USED AVAIL REFER MOUNTPOINT
bigpool/mynewfs 24.5K 4.81T 24.5K /mynewfs
Note that I am not having to edit /etc/vfstab or create the mount points: ZFS doesn't use /etc/vfstab unless you want it to (see "Legacy Mountpoints" in the ZFS Administration Guide ) and ZFS creates the mount points for you as well..it is as simple as that.
I am fickle; I now want to change the mount point without destroying the file system...
root# zfs set mountpoint=/fickle bigpool/mynewfs
root# zfs list bigpool/mynewfs
NAME USED AVAIL REFER MOUNTPOINT
bigpool/mynewfs 24.5K 4.81T 24.5K /fickle
Job done. By the way, this won't work if the file system is busy...see below..
root# cd /fickle
root# zfs set mountpoint=/ohnoyoudont bigpool/mynewfs
cannot unmount '/fickle': Device busy
All good fun!
Posted at 02:37PM Sep 03, 2007 in Storage |
