Public bug reported:
Binary package hint: squashfs-tools
# lsb_release -rd
Description: Ubuntu 10.10
Release: 10.10
# apt-cache policy squashfs-tools
squashfs-tools:
Installed: 1:4.0-8
Candidate: 1:4.0-8
Version table:
*** 1:4.0-8 0
500 http://us.archive.ubuntu.com/ubuntu/ maverick/main amd64 Packages
100 /var/lib/dpkg/status
I attempted to make a series of squashfs filesystems. (Many times!).
I'm using The Transparent Archivist (ftp://ftp.flaterco.com/ta/) to
organize the making of the filesystems; this tool calls mksquashfs
repeatedly as it divides a directory-to-be-archived into CD- or DVD-
sized squashfs filesystems. I don't think Transparent Archivist is
implicated in the problem, whatever it is. As far as mksquashfs is
concerned, it is being invoked in the usual way as an independent
subprocess.
Sometimes -- not very often, maybe once in 30-60 invocations --
mksquashfs simply hangs. Having made some of the filesystem it's
supposed to be making, It stops making the filesystem for no apparent
reason. It continues to use a wee bit of processing power after that --
very occasionally rising to the top of the "top" display -- but it makes
no observable progress on the filesystem that it's supposed to be
making. Once I left it running for 4 days; no progress, and no
resumption of work occurred during all that time.
Reading about mksquashfs's earlier bugs led me to edit the Transparent
Archivist's source code in such a way as to add '-no-sparse' to the
invocation parameters of the call to mksquashfs. This change did not
fix the problem; the occasional hanging continued just as before.
I also read Philip Lougher's remarks in Launchpad about problems in
earlier Ubuntu distros with mixing kernel module versions and mksquashfs
versions incorrectly, with respect to lzma support/defaulting. One fix
for that earlier "bug" was to invoke mksquashfs with -no-lzma. The
version of mksquashfs in my 10.10 distro does not recognize that
argument, so there's no way to try that fix.
It's important that you understand that, while I can reliably reproduce
the error, it often takes many invocations of mksquashfs to do so, and
the number of invocations cannot be predicted, EVEN FOR EXACTLY THE SAME
DATA. When mksquashfs hangs, and I abort it manually, I can restart
mksquashfs with exactly the source data and invocation parameters, and
so far it has always worked just fine when I do that.
You're about to ask me, "Is your hardware stable?". The answer is
"Yes". If this is a hardware problem, it is one that appears ONLY
during mksquashfs processing and at no other time. No other
applications are affected by it, and no rebooting is necessary even when
it does happen. Everything else works perfectly.
Realizing that mksquashfs uses all 8 threads of my i7-950 processor, I
have checked its temperature during maximum mksquashfs-mediated loads,
and it always stays below 55 C, and usually below 45C. And all other
processes continue to work without a hitch. So I don't think this is a
hardware problem.
Could "ionice -c 3" be implicated? It's something to think about,
anyway. I need to use that in order to keep the computer useful for
small interactive tasks during these giant, days-long archiving jobs.
However, the hanging problem was occurring before I started using
ionice.
** Affects: squashfs-tools (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/722168
Title:
mksquashfs hangs
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