Monday, April 12, 2010

Xen + ZFS = The Free VI Experiment

Having wrapped up last year's Physical to Virtual project, I decided to take stock of the progress made in the free/opensource virtualization and storage areas - how would the featuresets of commercial hypervisors and storage stack up against their lowcost/free counterparts?

We are a VMWare + NetApp shop for the most part in our production VI - we like to be able to call support when we have an issue in production

Thanks to the dozens of servers we virtualized, we have plenty of hardware to use for this in the lab.
For this experiment I decided to start with Sun's ZFS. Recently the dedeplication feature was added to ZFS. I downloaded and installed build 129 of Solaris and created a 1 Tb zfs pool, then created filesystems and shared them out via NFS for the Xenservers to use.
I turned on dedup and copied 386Gb of VMs from Netapp volume to the ZFS filesystem.
Here is how the dedup savings stacked up:
ZFS:
fcocquyt@lab-zfs-01:~ 2:05pm 1 > zpool list
NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT
data1 928G 103G 825G 11% 4.01x ONLINE -
fcocquyt@lab-zfs-01:~ 2:06pm 2 > zfs list
NAME USED AVAIL REFER MOUNTPOINT
data1/vms 386G 806G 386G /data1/vms
ZFS saved 386-103= 283Gb (283/386 = 73%)


Netapp (ONTap 7.3.1.1):
netapp-01> df -sh
Filesystem used saved %saved
/vol/vm2/ 167GB 229GB 58%


Ok, so ZFS is able to get 73-58=15% better dedup ratio - nice for a free solution!

Xen:
Then I loaded Xenserver 5.5 on 3 old Sunfire x2100's (AMD CPU) each with 2Gb ram
I installed Xencenter and created a pool and used the update tool in Xencenter to update them all to 5.5 U1 and configure the NFS datastore shared from the ZFS system.
I uploaded a CentoS5.3 ISO and Windows 7 ISO and used Xencenter to create a new VM of each flavor.
VM Migration: once I installed xentools I was able to live migrate (VMWare calls this vMotion) the new VMs around the pool's nodes live (each vmotion took < style="font-weight: bold;">What's missing:

In terms of the core featuresets there really is not much missing:
Netapp vs ZFS: both have snapshots, dedup, remote replication
VMWare vs Xenserver: both have snapshots, vMotion, P2V (Have not tried Xen's yet), centralized management

Conclusion: I was very impressed that in less than a day I could setup a free virtual infrastructure in the lab as a proof of concept to compare featuresets with the commercial VI solutions.

1 comment:

VCP #20255 said...

XenServer unit share jumped from 3% in 2008 to 11% at the end of 2009

http://virtualization.info/en/news/2010/04/citrix-announces-q1-2010-earnings-xenserver-market-share-at-11.html