[Evms-devel] Patch for snapshotting an XFS volume?

[Chia C. <chi...@zy...>]

Hi,

We cannot reliably create snapshot objects from XFS volumes. The software
versions are: kernel 2.4.23 with XFS, device-mapper 1.00.07, and evms 2.2.1.
I found the following article that seems to indicate that some kind of patch
is required to make snapshotting on XFS working.

http://www.kerneltraffic.org/kernel-traffic/kt20031027_238.html#4

"4. Status Of LVM With Journaled Filesystems In 2.4
15 Oct 2003 - 17 Oct 2003 (8 posts) Subject: "LVM Snapshots"
Topics: Disk Arrays: LVM <topics/Disk_Arrays-_LVM.html>, FS: JFS
<topics/FS-_JFS.html>, FS: ReiserFS <topics/FS-_ReiserFS.html>, FS: XFS
<topics/FS-_XFS.html>, FS: ext3 <topics/FS-_ext3.html>, Virtual Memory
<topics/Virtual_Memory.html>
People: Marcelo Tosatti <quotes/Marcelo_Tosatti.html>, Philippe Troin
<quotes/Philippe_Troin.html>, Marc-Christian Petersen
<quotes/Marc-Christian_Petersen.html>
Christoph Pleger discovered that he was unable to use LVM with the XFS
filesystem under kernel 2.4.22; in fact, ext3 and ReiserFS wouldn't work
with LVM either. Only JFS filesystem snapshots could be mounted with LVM.
After doing some research, he learned that an additional kernel patch was
needed to get LVM working with these other filesystems; but he couldn't
locate that patch. He asked if anyone had any pointers. Marc-Christian
Petersen posted it to the list, but added that Marcelo Tosatti had decided
not to include it in the 2.4 kernel sources. Philippe Troin searched the
archives for that discussion, but with no luck, and asked why Marcelo had
made that decision. Marc-Christian said it took place in private email; and
posted the relevant bit. In that email, from September 2003, Marcelo had
said he wanted to add some VM patches first, and that "LVM has already been
updated on 2.4.23-pre. Lets do more changes later on." Philippe thanked
Marc-Christian, and summarized, "Nothing technical then, Marcelo is just
being slow for stability's sake and easier testing. I guess that will go in
somewhere in a later 23-pre or in 24." Meanwhile, Marcelo also replied to
the list, explaining that the LVM patch had not been accepted "Because the
patch touches generic fs code. Dont use LVM with XFS for now." Christoph
Pleger said he'd used LVM and XFS together without a problem, and asked why
Marcelo had issued that caution. Marcelo replied:
Because the filesystem code lacks locking somewhere (thats what the patches
adds).
It seems its not safe to create snapshots of journalled fs'es without this
patch."

Please help me to find the latest version of this patch.

Thanks

Chia
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