On Mon, 2004-09-13 at 00:45, Bryan J. Smith wrote:
> I'll have to research more, but there seems to be a _lot_ of post-stock
> 2.4 patches for XFS.
- Foreword ...
I started with my own RPM builds for Red Hat Linux 7.0 from SGI's
"stable" tag in CVS in February 2001 (they would release XFS 1.0 for Red
Hat Linux 7.1 based on that tag 2 months later, with a full
CD/installer). Since then, my systems have been largely Red Hat Linux
7.3 (XFS 1.2) and 9 (XFS 1.3.1) with the official SGI kernel and
user-space RPMs (the last being 2.4.20). From what I've seen, trying to
use any other 2.4 offering has caused most people a lot of grief.
Most of my prior knowledge of XFS and the stock kernel integration comes
from the 2.5.3+ announcements and the kernel congress news through
mid-way through the 2.5 release cycle. E.g., from the FAQ:
http://oss.sgi.com/projects/xfs/faq.html#linuskernel
"XFS is included in the 2.5 series as of 2.5.36.
We might even be included at some point in the 2.4 series when some
2.5 features are backported. There are more core kernel changes for
2.4, so the patch is a bit more intrusive. Still, the easiest way to
get the "latest and greatest" is by checking the out the xfs
development tree by cvs."
Since 2.6 became available, I instantly looked to testing XFS again. I
waited a few months after the Fedora Core 2 (CL4.0) release, as it was a
first ".0" revision in the traditional Red Hat distribution release
cycle. In a nutshell, I waited for at least 1 kernel revision (to
2.6.5). As such, I have just started deploying XFS "test systems"
w/FC2. I still use root (/) as Ext3, for recoverability considerations
(so I can still boot any 2.4 recovery CD, or other 2.4-based utility).
- On to the merge and other details ...
Okay, I found it, the first 2.4.24 pre-release (mid-Dec 2003):
http://www.kerneltraffic.org/kernel-traffic/kt20031226_246.html#3
In early October, basically as 1.3 (and subsequent 1.3.1) was released,
Hellwig did an _excellent_ status overview:
http://verein.lst.de/~hch/xfs/status.txt
You'll quickly note why SGI continues to favor Alan Cox (Red Hat)
kernels. Of all the major commercial distros, at least from my very
NetApp/Solaris-centric background, I always found (and still find) Red
Hat provided (provides) the most "direct" UNIX experience/expectations.
The "core" subsystem modifications are largely "static" now according to
the README:
ftp://xfs.org/mirror/SGI/Release-1.3.1/README
As such, it looks like SGI changed their stance on XFS in 2.4 in early
December 2003 (around 2.4.21/22) -- about 6 weeks after the 1.3.1
release. This is a _major_ change in SGI's view -- they were always
_anal_ on the inclusion of XFS in the stock 2.4, and didn't "push" Linus
like a _lot_ of the other filesystems (e.g., ReiserFS shipped in stock
2.4.1 without a _lot_ compatibility, and JFS had similar, massive
support missing too when it was added).
Tosatti originally rejected the idea, considering the common attitude
that it should only be in 2.6. I can only assume SGI figured it was "as
good as it would get for 2.4" and wanted to "get in" before the 2.4.25
'maintenance mode' freeze:
http://www.kerneltraffic.org/kernel-traffic/kt20031208_244.html#7
*UNFORTUNATELY* it looks like SGI XFS in 2.4 is very "stripped down."
In other words, things that affect major subsystems are _not_ included
in 2.4. So I would _not_ use 2.4 XFS in production. Just my view based
on this nugget:
http://www.kerneltraffic.org/kernel-traffic/kt20031214_245.html#9
As well as looking through the massive, elementary patches in the
ChangeLogs that are being made to 2.4.24+ and not as many as 2.6.x.
2.6.x continues to look a heck of a lot better for XFS IMHO. I'm sure
SGI would agree that 2.6 is the better path, especially in the
near-future. Their change in view on 2.4 seems to be driven by the fact
that 2.6 "isn't there yet" (i.e., well accepted by distributors and/or
deployed by users), and the backports to 2.4 were sufficient to support
XFS to an acceptable degree for future maintenance.
I think their reference to maintaining their own tree for 3+ years,
syncing back in the various changes for each kernel patchlevel, really
says, "hey, we've merged all the changes with every patchlevel version,
and now we're seeing very few things that need to change for XFS." Not
as good as 2.6, but "good enough."
- Final comments ...
XFS has been very "production quality" for a long time. XFS has
supported more "standard Linux interfaces" from Day 1 than any other
journaling filesystem. But SGI was 100x more anal on having the "full
support" there for everything in the Linux kernel before deploying.
-- Bryan J. Smith b.j.smith@ieee.org ------------------------------------------------------------------ "Communities don't have rights. Only individuals in the community have rights. ... That idea of community rights is firmly rooted in the 'Communist Manifesto.'" -- Michael Badnarik----------------------------------------------------------------------- This list is provided as an unmoderated internet service by Networked Knowledge Systems (NKS). Views and opinions expressed in messages posted are those of the author and do not necessarily reflect the official policy or position of NKS or any of its employees.
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