[CentOS] centosplus kernel (XFS)

Bryan J. Smith thebs413 at earthlink.net
Thu Oct 27 17:39:20 UTC 2005

Ajay Sharma <ssharma at revsharecorp.com> wrote:
> I'm not a 'filesystem' guy, but is my assumption correct
> that XFS is great for large files and reiserfs is good for
> a ton of tiny files?

I'm not going to get deep into that.  XFS has lots of
features to avoid fragmentation and other issues.  Some of
those features tend to be more of an issue when you have lots
of smaller, temporary files.  But XFS is great for
filesystems where you have a combination of small and large
-- far better than most other implementations.

The reason *I* like to run XFS are:

#1  Structure hasn't changed in 10 years
#2  Very, very trusted off-line repair (if on-line fsck
detects an issue) -- largely because of #1 (hasn't changed in
10 years!)
#3  On-line fsck, On-line fragmentor, On-line copy/dump
#4  Extended Attributes (EAs) for things like Access Control
Lists (ACLs), Quotas and SELinux are natively supported in
inodes -- which means on-line copy/dump transfers them

> On my mail server, I used reiserfs.  Is there a better
> (faster) filesystem choice here?

ReiserFS doesn't use a traditional UNIX inode layout and
requires various support modules to emulate them for NFS,
Quotas, EAs, etc...  And many of those features are broken.

But my #1 issue with ReiserFS has been the constant
structural changes.  Even if you trust the journal, if a
journal replay doesn't resolve all consistencies, I've
regularly run into the issue where the off-line fsck tools
are not "up-to-date" with structural changes.

My first move _before_ running any fsck on ReiserFS is to do
a full dd of the slice.  Why?  Because 9 times out of 10, I'm
going to lose the filesystem when I run reiser.fsck.

> And on my MythTV box at home, I used XFS 
> because the only thing on the partition is large video
> files.

The problem with XFS is the lack of support by the distro
vendors.  I don't trust the stock kernel XFS implementation,
and I don't trust vendors to include the proper user-space

With Red Hat and kernel 2.6, that 4KiB stacks is the main
issue SGI is having.  If an SGI XFS team member addresses
that, then maybe it's the start of Red Hat's interest.

The last XFS system I put into "heavy production" was a
RHL7.3/XFS1.2 implementation.  I tested a RHL9/XFS1.3 system
with lighter duties.  Ironically, once XFS went into the
stock 2.4 kernel/backport, it was far worse -- the 2.6
release is not what I expected either, but at least it's not
as bad.

There are severe limitations to Ext3 that ReiserFS v3 doesn't
solve, and ReiserFS v4 still has a lot of the same
compatibility issues of ReiserFS v3.  So AFAIAC,
professionally, XFS is the only filesystem that augments Ext3

Bryan J. Smith                | Sent from Yahoo Mail
mailto:b.j.smith at ieee.org     |  (please excuse any
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