CentOS - Jul 2007 - NFS filesystem recommendations please (and problems with XFS)

Hello all,

I am implementing a new mail server into our environment consisting of 
three machines - two Dell Opterons that will act as load balanced 
Postfix servers, and a 1.5TB RAID10 NFS server.  All three machines are 
running CentOS 4.5.

Since the NFS is going to be used for only mail, I was kicking around 
the idea to use XFS.  I have CentOS installed on an ext3 partition, and 
with the leftover space on the NFS I created an XFS partition.  I tried 
to implement XFS into the kernel, and was coming across some issues.  
Even after installing xfprogs and xfsprogs-devel, and issuing the command:

yum --enable-plusrepos install kernel

I booted up the kernel and still could not mount my XFS share.  I keep 
getting this error:

mount: fs type xfs not supported by kernel

After googling around (and not finding out how to get XFS enabled in the 
kernel), people had some concerns about using XFS due to issues and it 
being about as fast as ext3. 

Also people said that I might run into issues with XFS if I run 
NFS+lvm+xfs+md but I'm not sure if I run lvm and md and if that applies 
to me.

I found this benchmarking blog someone wrote that compares the speeds in 
Ubuntu with all the filesystems in a Postfix server environment 
(although it's not NFS):

http://piao-tech.blogspot.com/2007/04/file-system-benchmarks-for-postfix-mail.html

With all this said, I'd like to use XFS, if it indeed is going to be the 
fastest for the solution I want to implement.  If you guys can help me 
get that installed by telling me what I need - great!  If you think XFS 
isn't going to work as efficiently and fast as I want it to, and there 
is another filesystem (such as ext3) that will be more stable and just 
as fast in my setup, I'm all ears.

Thanks everyone in advance.

Patrick

On 7/21/07, Patrick - South Valley Internet <patrickm at garlic.com>
wrote:
> Hello all,
>
> I am implementing a new mail server into our environment consisting of
> three machines - two Dell Opterons that will act as load balanced
> Postfix servers, and a 1.5TB RAID10 NFS server.  All three machines are
> running CentOS 4.5.
>
> Since the NFS is going to be used for only mail, I was kicking around
> the idea to use XFS.  I have CentOS installed on an ext3 partition, and
> with the leftover space on the NFS I created an XFS partition.  I tried
> to implement XFS into the kernel, and was coming across some issues.
> Even after installing xfprogs and xfsprogs-devel, and issuing the command:
>
> yum --enable-plusrepos install kernel
>
> I booted up the kernel and still could not mount my XFS share.  I keep
> getting this error:
>
> mount: fs type xfs not supported by kernel
You need to install kernel-module-xfs from the centosplus repo.

Akemi

On Saturday 21 July 2007, Patrick - South Valley Internet wrote:
...
> After googling around (and not finding out how to get XFS enabled in the
> kernel), people had some concerns about using XFS due to issues and it
> being about as fast as ext3.
>
> Also people said that I might run into issues with XFS if I run
> NFS+lvm+xfs+md but I'm not sure if I run lvm and md and if that applies
> to me.
Just a few random opinions/thoughts on the topic.

* more components (nfs, fs, lvm, ...) uses more stack space
* xfs eats stack this is why it's not really good on 32-bit (4K stack)
* performance diff vs. ext3 varies not only with work load but also with 
hardware
* ext3 is much more widely used and wont cause you any head aches when a new 
kernel arrives

/Peter 
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Am Samstag, 21. Juli 2007 schrieb Patrick - South Valley
Internet:
> With all this said, I'd like to use XFS, if it indeed is going to be
the
> fastest for the solution I want to implement. ?If you guys can help me
> get that installed by telling me what I need - great! ?If you think XFS
> isn't going to work as efficiently and fast as I want it to, and there
> is another filesystem (such as ext3) that will be more stable and just
> as fast in my setup, I'm all ears.
Just to add some positive feedback: I implemented XFS on an x86_64 box running 
CentOS around here. The machine is an NFS, Samba and Emailserver (kolab, that 
means postfix + cyrus imapd). The machine has a Hardware SCSI RAID with 8 10k 
U320 HDs. So far we had a minor issue with some small undeletable files that 
could be tracked down to a XFS bug (which is fixed by now). Other than that 
the box has been running rock stable. We started with CentOS 4.2 or 4.3 and 
are now at 4.5 via continuous yum updates.

Before the machine went into production I had about two weaks for doing heavy 
benchmarking and some reinstalls. Using XFS and tuning the parameters of the 
RAID array gave a massive performance boost. I also tried tuning ext3 but got 
only about half the throughput than with XFS, so I decided to go XFS.

Of course these results depend on usage pattern, hardware, etc. So do your own 
benchmarks. I myself asked our heavies nfs users for their homedirs or parts 
of it and benchmarked by copying these around in parrallel. This was quite 
enlightening and much more useful than artifical benchmarks.

regards,
Andreas Micklei

-- 
Andreas Micklei
IVISTAR Kommunikationssysteme AG
Ehrenbergstr. 19 / 10245 Berlin, Germany
http://www.ivistar.de

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