[CentOS] centosplus kernel (XFS)

[Bryan J. Smith]

Dan Pritts <danno at internet2.edu> wrote:
> How current is this experience?  

I've never tried ReiserFS on Red Hat.  But it was as current
as SuSE Linux 9.x and Mandrake Linux 9.x.  Prior to Mandrake
Linux 9.x, I found Mandrake notorious for not keeping the
reiserfs tools consistent with their kernels.

> I hear from proponents that reiser admittedly had problems
> in early days but they've cleaned up their act.

Linus forced them to stop changing structures so radically so
often.  But still, there are still a lot of kernel-driver
changes that don't always make it into the mkfs.reiserfs
off-line tools.

Let me say that again ... I *DO* believe the kernel
implementation of ReiserFS is quite *RELIABLE*, maintaining
good consistency and an effective meta-data journal (never
tried full-data with it).  Other than various feature
support, I've _never_ had a problem there.

*BUT* if you find yourself in a pickle where the filesystem
cannot be made consistent by the journal, and have to do a
full fsck.reiserfs -- _avoid_ throwing that "-y" option.  9
times out of 10, you're going to have issues.

Furthermore, if you use a _stock_ kernel, instead of relying
on the distro's, then _you_ are responsible for making sure
you have the appropriate reiserfs user-space/off-line tools
for that kernel implementation.  With Ext3 and XFS, their
structures virtually never change, so you're typically safe
-- or always safe by upgrading to the latest
user-space/off-line tools for those filesystems.

Which is why I prefer filesystems that don't constantly
change in structure.

> Can you elaborate?  I thought that 2.6 kernels had merged
> the mainline XFS stuff.

They did.  Much of the support required in the kernel for XFS
was added in the 2.5 series.  Many other filesystems also use
that support to.  But there is a lot of XFS errata if you
look through the reports and revisions.  ;->

In fact, I've been running XFS on the Fedora Core 2+ releases
with no reliability issues -- but I'm not running anything
serious on them.  Unfortunately, I've run into NFS issues. 
And no one seems to trust XFS on 4K stacks, which Fedora Core
does use.

As far as the kernel 2.4 backport, don't even bother.  I've
seen a lot of people with lots of problems, and the kernel
2.4 errata for XFS seems rather scary.

> I can't find any discussion of problems on the
> XFS web site

Join the mailing lists.  ;->

> and the "xfs/download/latest" area on oss.sgi.com has
> files dated 2003.

Yes, because the last "official" release was for Red Hat
Linux 9.  The official releases for Red Hat Linux 7.3 and 9
are ones I actually still have running in production (nearly
all are 7.3, XFS 1.2).  Those kernels are SGI's own 2.4
kernel with their own XFS mergers (pre-backport from 2.6 that
is now in the stock 2.4 kernel).

Everything since has been in SGI's CVS tree for XFS.  The XFS
team maintains their own, _full_ kernel tree in CVS.  I
seriously _doubt_ distros are pulling in all those SGI
changes into their kernels.  They are most likely just
relying on the stock kernel XFS work.

Which is _not_ synchronized with more recent XFS work AFAICT.


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