[dm-crypt] writing greater than 1GB of data through the mapper to a file hangs kernel 3.2.x
arno at wagner.name
Fri Jul 6 07:06:27 CEST 2012
On Thu, Jul 05, 2012 at 05:03:40PM -0400, .. ink .. wrote:
> > I am using pclinuxos and "uname -a" gives:
> > Linux mtz 3.2.18-pclos2.bfs #1 SMP PREEMPT Thu May 24 04:44:50 CEST
> > 2012 i686 i686 i386 GNU/Linux
> > Using this kernel version:
> > i created a 2GB file using dd, then i opened a plain mapper on the
> > file and then attempted to write 1GB of data through the mapper using
> > dd and the system lock up. I tried it 3 times and it lock up 3 times.
> just to add to above with test results:
> i created a 2GB file, then run the following commands to see where it
> would lock up
> [root at mtz ink]# dd if=/dev/zero of=/dev/mapper/zzz bs=1024 count=110K
> 115343360 bytes (115 MB) copied, 7.15232 s, 16.1 MB/s
> [root at mtz ink]# dd if=/dev/zero of=/dev/mapper/zzz bs=1024 count=140K
> 146800640 bytes (147 MB) copied, 4.80232 s, 30.6 MB/s
> [root at mtz ink]# dd if=/dev/zero of=/dev/mapper/zzz bs=1024 count=200K
> 209715200 bytes (210 MB) copied, 9.2493 s, 22.7 MB/s
> [root at mtz ink]# dd if=/dev/zero of=/dev/mapper/zzz bs=1024 count=500K
> 524288000 bytes (524 MB) copied, 36.333 s, 14.4 MB/s
> [root at mtz ink]# dd if=/dev/zero of=/dev/mapper/zzz bs=1024 count=800K
> 838860800 bytes (839 MB) copied, 205.896 s, 4.1 MB/s
> The last one locked the system couple of times but it managed to succeed.
> I then attempted to write 900MB to /dev/mapper/zzz and the system
> locked up and had to hard power down two hours later..
just tried this with 3.3.8 (self-compiled from kernel.org) on top
of debian Squeeze:
R gatewagner:~/f/luks# dd if=/dev/zero of=/dev/mapper/e1 bs=1024 count=500K
524288000 bytes (524 MB) copied, 11.0068 s, 47.6 MB/s
R gatewagner:~/f/luks# dd if=/dev/zero of=/dev/mapper/e1 bs=1024 count=800K
838860800 bytes (839 MB) copied, 18.7919 s, 44.6 MB/s
R gatewagner:~/f/luks# dd if=/dev/zero of=/dev/mapper/e1 bs=1024 count=900K
943718400 bytes (944 MB) copied, 18.6192 s, 50.7 MB/s
R gatewagner:~/f/luks# dd if=/dev/zero of=/dev/mapper/e1 bs=1024 count=2000K
2097152000 bytes (2.1 GB) copied, 44.9154 s, 46.7 MB/s
What I notice is that your transfer speeds are awfully low compared
to mine. And my set-up is slow with a 3-way RAID 1 on 5400rpm 2.5" disks.
Your speed seems to be dropping with larger transfers, something which
it should not do (unless you write enough to change disk zones) and which
I do not see in my system.
I suspect this is a different problem, e.g. a dying and/or overheating
controller. It may also be a RAM problem that only hits on large
enough transfers. See cryptsetup FAQ on how to test RAM.
> first time experience like the one reported here in the second
> paragraph: http://www.pclinuxos.com/forum/index.php/topic,106847.msg912803.html#msg912803
That looks like a ZuluCrypt artefact to me, not something you would
see with cryptsetup.
Arno Wagner, Dr. sc. techn., Dipl. Inform., Email: arno at wagner.name
GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
One of the painful things about our time is that those who feel certainty
are stupid, and those with any imagination and understanding are filled
with doubt and indecision. -- Bertrand Russell
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