April 2007 Archives

Ok, ZFS is now in the tree, what's now? Below you'll find some
instructions how to quickly make it up and running.

First of all you need some disks. Let's assume you have three spare SCSI
disks: da0, da1, da2.

Add a line to your /etc/rc.conf to start ZFS automatically on boot:

        # echo 'zfs_enable="YES"' >> /etc/rc.conf

Load ZFS kernel module, for the first time by hand:

        # kldload zfs.ko

Now, setup one pool using RAIDZ:

        # zpool create tank raidz da0 da1 da2

It should automatically mount /tank/ for you.

Ok, now put /usr/ on ZFS and propose some file systems layout.  I know
you probably have some files already, so we will work on /tank/usr
directory and once we ready, we will just change the mountpoint to /usr.

        # zfs create tank/usr

Create ports/ file system and enable gzip compression on it, because
most likely we will have only text files there. On the other hand, we
don't want to compress ports/distfiles/, because we keep compressed
stuff already in-there:

        # zfs create tank/usr/ports
        # zfs set compression=gzip tank/usr/ports
        # zfs create tank/usr/ports/distfiles
        # zfs set compression=off tank/usr/ports/distfiles

(You do see how your life is changing, don't you?:))

Let's create home file system, my own home/pjd/ file system. I know we
use RAIDZ, but I want to have directory where I put extremly important
stuff, you I'll define that each block has to be stored in tree copies:

        # zfs create tank/usr/home
        # zfs create tank/usr/home/pjd
        # zfs create tank/usr/home/pjd/important
        # zfs set copies=3 tank/usr/home/pjd/important

I'd like to have directory with music, etc. that I NFS share. I don't
really care about this stuff and my computer is not very fast, so I'll
just turn off checksumming (this is only for example purposes! please,
benchmark before doing it, because it's most likely not worth it!):

        # zfs create tank/music
        # zfs set checksum=off tank/music
        # zfs set sharenfs=on tank/music

Oh, I almost forget. Who cares about access time updates?

        # zfs set atime=off tank

Yes, we set it only on tank and it will be automatically inherited by
others.

Will be also good to be informed if everything is fine with our pool:

        # echo 'daily_status_zfs_enable="YES"' >> /etc/periodic.conf

For some reason you still need UFS file system, for example you use ACLs
or extended attributes which are not yet supported by our ZFS. If so,
why not just use ZFS to provide storage? This way we gain cheap UFS
snapshots, UFS clones, etc. by simply using ZVOLs.

        # zfs create -V 10g tank/ufs
        # newfs /dev/zvol/tank/ufs
        # mount /dev/zvol/tank/ufs /ufs

        # zfs snapshot tank/ufs at 20070406
        # mount -r /dev/zvol/tank/ufs at 20070406 /ufs20070406

        # zfs clone tank/ufs at 20070406 tank/ufsok
        # fsck_ffs -p /dev/zvol/tank/ufsok
        # mount /dev/zvol/tank/ufsok /ufsok

Want to encrypt your swap and still use ZFS? Nothing more trivial:

        # zfs create -V 4g tank/swap
        # geli onetime -s 4096 /dev/zvol/tank/swap
        # swapon /dev/zvol/tank/swap.eli

Trying to do something risky with your home? Snapshot it first!

        # zfs snapshot tank/home/pjd at justincase

Turns out it was more stupid than risky? Rollback your snapshot!

        # zfs rollback tank/home/pjd at justincase
        # zfs destroy tank/home/pjd at justincase

Ok, everything works, we may set tank/usr as our real /usr:

        # zfs set mountpoint=/usr tank/usr

Don't forget to read zfs(8) and zpool(8) manual pages and SUN's ZFS
administration guide:

        http://www.opensolaris.org/os/community/zfs/docs/zfsadmin.pdf

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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