FFS corruption

[Emmanuel Dreyfus <manu%netbsd.org@localhost>]

Hello

I experienced some nasty FFS corrupton, which was only resolved by
reformatting.L

The filesystem was a root partition image for a Xen NetBSD-7.1/i386 
domU. It was formatetd FFSv1 level 4. Everything was fine until I 
scp it over the network on a new machine. 

After this migration, the filesystem started corrupting the same file
/usr/pkg/etc/httpd/httpd.conf at the same time, which happens to be
/etc/daily end of execution. Other files were affected, ncluding a
/usr/pkg/etc/httpd/httpd.conf.bak set there to recover, but it is
difficult to asset the span of the problem. I assume few files were
touched because the machine could still work after just restoring 
httpd.conf

httpd.conf metadata did not change, its content was just filed with 
some fixed length binary records (sample included below, in case it 
rings a bell to someone). Setting immutable flags did not prevent the 
corruption; And using ktrace on /etc/daily showed it did not touch 
httpd.conf nor even its parent directory.

And fsck did not fid anything wrong. Is there anything ringing a bell
to someone here? Any explanation?

Corrupted httpd.conf sample:
00000000  80 81 01 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000010  5a 8d 0e 5a 60 8e 09 0f  5a 8d 0e 5a 60 8e 09 0f  |Z..Z`...Z..Z`...|
00000020  5a 8d 0e 5a 60 8e 09 0f  00 00 00 00 00 00 00 00  |Z..Z`...........|
00000030  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000060  00 00 00 00 00 00 00 00  00 00 00 00 f4 4e a9 72  |.............N.r|
00000070  90 01 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000080  80 81 01 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000090  7f 8d 0e 5a 7e 77 dc 25  7f 8d 0e 5a 7e 77 dc 25  |...Z~w.%...Z~w.%|
000000a0  7f 8d 0e 5a 7e 77 dc 25  00 00 00 00 00 00 00 00  |...Z~w.%........|
000000b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
000000e0  00 00 00 00 00 00 00 00  00 00 00 00 8b 73 ed 77  |.............s.w|
000000f0  90 01 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000100  80 81 01 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000110  92 8d 0e 5a 54 43 af 15  92 8d 0e 5a 54 43 af 15  |...ZTC.....ZTC..|
00000120  92 8d 0e 5a 54 43 af 15  00 00 00 00 00 00 00 00  |...ZTC..........|
00000130  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*



-- 
Emmanuel Dreyfus
manu%netbsd.org@localhost