Here we go again.

After installing ZFS on a Debian based Proxmox Node I now need some bang on a CentOS Server.

To remind you all: ZFS on Linux is considerably stable and matured, but you put it in place on your own risk.

ZFS Native comes from http://zfsonlinux.org/

I use a Centos 6.3 minimal installation and I have a 2GB disk configured to it for demo.

fdisk -l Disk
/dev/sdb: 2147 MB, 2147483648 bytes

Updated (26.04.2013)
And a Russian fellow describes his way to install it which I used and improved. http://habrahabr.ru/post/152853/

He build his own repo under http://yum.aclub.net/pub/linux/centos/6/umask-zfsonlinux/x86_64/ which is maintained as per 05.03.2013

So we start with:

cd /etc/yum.repos.d/
wget http://yum.aclub.net/pub/linux/centos/6/umask-zfsonlinux/umask-zfsonlinux.repo
rpm --import http://yum.aclub.net/pub/linux/centos/5/umask/RPM-GPG-KEY-umask

There is an original repo from zfs on Linux now which we are going to use since it has the latest version 0.6.1 of ZFS http://zfsonlinux.org/epel.html

yum localinstall --nogpgcheck 

If you don’t have yet enabled the EPEL repo please do now cause we need a pew packages from there. You can find details here or else: Obsulete since 08.2013 due to dkms in epel with a incompatible version

rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm

We now install DKMS and all necessary packages for building the kernel modules:

yum update
yum install dkms gcc make kernel-devel perl

And now we come to the serious stuff … installing zfs ..

yum install spl zfs

That might take a while now depending on the machine performance since its compiling the packages.

You now better turn on ZFS in case you plan to reboot that server again.

chkconfig zfs on

That should do the jobs now. you can see it it works by running

# zpool status
no pools available

Now lets configure some ZFS. For a deeper howto please refer for example to http://www.datadisk.co.uk/html_docs/sun/sun_zfs_cs.htm

It is advised to use if possible a full disk and let it hand by zfs rather than a slice.

# zpool create -f zfs-data /dev/sdb

zpool status shows what we just configured

# zpool status
pool: zfs-data
state: ONLINE
scan: none requested
config:
NAME        STATE     READ WRITE CKSUM
zfs-data    ONLINE       0     0     0
sdb       ONLINE       0     0     0
# zfs list
NAME       USED  AVAIL  REFER  MOUNTPOINT
zfs-data   104K  1.95G    30K  /zfs-data

In general you could now already use /zfs-data as a filesystem.

We can create underneath another filesystem.

We need to check first the permissions of /zfs-data it sometimes is set wrongly.

chmod 755 /zfs-data
zfs create zfs-data/compressed

Lets quickly turn on compression.

zfs set compression=on zfs-data/compressed

zfs list
NAME USED AVAIL REFER MOUNTPOINT
zfa-data 141K 1.95G 30K /zfa-data
zfa-data/compressed 30K 1.95G 30K /zfa-data/compressed

ZFS mounts the filesystems automatically when booting the system.

Kernel upgrade

If you run yum update and the kernel gets updated then please follow the following steps to update zfs on Centos:

in some occasions after upgrading the kernel it might happen that zfs is not able to load zfs.ko and returns a

Load the module manually by running 'insmod /zfs.ko' as root.

Try the following to fix this. search first for your kernel version. (in this case you will see that I use a openvz kernel)

uname -a
Linux oVirt 2.6.32-042stab077.7 #1 SMP Mon Apr 22 14:59:15 MSK 2013 x86_64 x86_64 x86_64 GNU/Linux

make sure you have the kernel headers installed.

yum whatprovides kernel-headers

search for 042stab077.7

install missing headers with

 yum install vzkernel-devel-2.6.32-042stab076.5.i686

In this case I had to take an earlier version because there were no headers for 77 and then get with yum -y upgrade the latest version 078 for the kernel and its headers. Reboot to go to the latest version if this has changed

reboot

reinstall zfs

yum reinstall dkms spl zfs spl-modules-dkms zfs-modules-dkms

That should work now