freebsd 7.0 ZFS Quick Start Guide

Ok, ZFS is now in the tree, what's now? Below you'll find some instructions how to quickly get 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 

Now, setup one pool using RAIDZ:

# zpool create tank raidz da0 da1 da2 

It should automatically mount /tank/ for you.

Ok, now we want to put /usr/ on ZFS and use some nifty file systems layout. I know you probably have some files already, so we will work on /tank/usr directory and once we are 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 most files in this directory are already compressed:

# 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 and my own home/pjd/ file system. I know we use RAIDZ, but I want to have directory where I put extremely important stuff, so I'll define that each block has to be stored in three 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.

Would 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@20070406
# mount -r /dev/zvol/tank/ufs@20070406 /ufs20070406

# zfs clone tank/ufs@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:

WARNING: Due the way ZFS is currently implemented (also in Solaris), this might not work in low memory conditions (i.e. at those times you really need the swap space). See http://lists.freebsd.org/pipermail/freebsd-current/2007-September/076831.html for more information.

# 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@justincase 

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

# zfs rollback tank/home/pjd@justincase 
# zfs destroy tank/home/pjd@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.

For a more light-hearted introduction to ZFS' features, see this humorous presentation given by Pawel at EuroBSDCon 2007: http://youtube.com/watch?v=o3TGM0T1CvE