Last I checked XFS was still supported; when tuned correctly it's still the fastest filesystem for database transaction logs (although some of the log-structured filesystem may eventually beat it).
EXT4 still has some significant performance issues and has regressed quite a bit in that regard in the past few kernels.

I just rechecked, and XFS support in RHEL/CentOS is part of the high-performance/high-scalability add-on in RHEL 5.6, and became "fully" supported in 5.7 (although it has been supported for a long time in the kernel), but there's no reason not to use it in CentOS 5.6 unless you have a paid support contract and didn't pay for the high-performance/high-scalability add-on (if that's even offered by your particular vendor).

XFS is also probably the most stable Linux native filesystem (other than EXT2/EXT3) as it's been in the kernel about as long as EXT3 and still has active development effort to improve quality/reliability/performance.

On 08/02/2011 12:19 AM, der.hans wrote:
> moin moin,
> 
> we have a mix of CentOS 5.x boxen. They're currently using ext3 for the OS
> and reiserfs for a RAID0 filesystem for fast writing. We have a couple
> hundred of them.
> 
> We've been experiencing a few kernel panics a month due to reiserfs.
> 
> At one point when researching the problem I found statements that reiserfs
> ( and XFS and JFS ) are not officially supported filesystems for RHEL 5.x
> and therefore also not for CentOS 5.x.
> 
> With 5.6 ext4 is now an officially supported filesystem.
> 
> Is there a list of officially supported filesystems for CentOS?
> 
> Any recommendations for a particular filesystem to use with CentOS 5.6 for
> fast log writing?
> 
> ciao,
> 
> der.hans