Re: Subject: [Xen-users] iSCSI vs NFS

[Grant McWilliams <grantmasterflash@xxxxxxxxx>]

On Tue, Feb 2, 2010 at 6:28 AM, Joseph Coleman <joe.coleman@xxxxxxxxxxxxxxxxxx> wrote:

Andy,

I did recently switch to iscsi in an ocfs2 format clustered on 2 servers for testing and it is a lot better. However, there is a current bug with it tht Novell is writing a patch for me on and I should hopefully have it today or tomorrow. I also have 2 other servers that have their own iscsi volumes tied to them. All in all I am extremely happy with the consistent performance I am getting for the ISCSI volumes and highly recommend them.

Pros and cons:

NFS:

Extemely easy to manage. And if you SAN provider has de-dupe support the NFS volumes de-dupe really good. But Performance is bad and will cause some thinning in the hairline.

Iscsi:

Consistent reliable performance can be used as a cluster aware file system depending how you format it out.

Doesn’t de-dupe nearly as well as NFS does and isn’t as easy to manage or resize on the fly like NFS so you need to keep an eye on your volumes and manage them a little more closely.

Hope this helps if you have further questions shoot me an email joe.coleman@xxxxxxxxxxxxxxxxxx

Joe,
    The iSCSI with OCFS is faster than NFS?  Where do you suppose the speed increase is coming from? It would seem that you have a lot more layers than before and the addition a clusterfs.  I haven't seen any recent speed tests on cluster fses but about 2 years ago another company I contracted with canceled their Xen deployment because the performance hit from GFS2 crippled their servers. It was somewhere in the order of 30% of the speed of native ext3 on local storage. I left the project after that so I'm not sure if they re-evaluated later. As I've mentioned in another thread I'm going to be doing extensive testing on these various methods.

Do you have any words of advice on your testing methods?


Grant McWilliams

Some people, when confronted with a problem, think "I know, I'll use Windows."
Now they have two problems.

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