Date: Mon, 18 Feb 2008 18:37:35 +0000 From: Gavin Atkinson <gavin.atkinson@ury.york.ac.uk> To: Richard Todd <rmtodd@ichotolot.servalan.com> Cc: freebsd-current@freebsd.org Subject: Re: ZFS: data sometimes not getting correctly flushed to disk (possible mmap/write issue)? Message-ID: <1203359855.43782.60.camel@buffy.york.ac.uk> In-Reply-To: <20080215231507.EAB7D641@mx2.synetsystems.com> References: <20080215231507.EAB7D641@mx2.synetsystems.com>
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On Fri, 2008-02-15 at 16:59 -0600, Richard Todd wrote:
> Bit of a long story behind this one: I've been playing with the "picard"
> program in ports to do re-tagging of audio (mp3/ogg) files, and was having
> problems with the tagging process creating corrupted .ogg files. On
> further investigation trying to debug this, I found that the "picard"
> program seemed to be correctly writing the files if I checked them
> immediately, but the files were corrupt when I looked at them later.
> Further investigation and coming up with test cases brought me to the
> surprising conclusion that ZFS was to blame -- under certain conditions ZFS
> seems not to be writing all the data in the file out to disk correctly.
> The file appears to be good only so long as the file's data is in cache, but
> the data actually on disk doesn't match what's in cache.
I don't currently have a system that I can test this with, but is there
any chance you could make the following change to your script?
#!/bin/sh
NAME=$1
LEN=$2
rm $NAME
./a.out $NAME $LEN
./gen2.py $NAME
md5 $NAME
+ cp $NAME /some/ufs/filesystem/$NAME.1
ls -l $NAME
sudo umount /u3
sudo mount -t zfs u3 /u3
md5 $NAME
+ cp $NAME /some/ufs/filesystem/$NAME.2
ls -l $NAME
+ md5 /some/ufs/filesystem/$NAME.?
and when you find files that differ, compare the two copies stored on
the UFS filesystem with cmp(1)? I'd be interested to know exactly what
the corruption looks like - is a single bit differen? Or was an entire
page destroyed?
Gavin
Gavin
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