Improving fsck With Regard to Bad Cylinder Groups

[John Kozubik]

Friends,

Kirk McKusick did some miscellaneous consulting for me earlier this year,
and new fsck functionality was the unexpected result.

Briefly:

A filesystem with bad cylinder groups would cause messages like:

fsck_ffs: cannot alloc 275829428 bytes for inoinfo

to be output by fsck, and dumpfs (before dumping core) would show cylinder
groups with obviously out of bounds data.

There were some patches floating around that added a '-D' option to fsck,
giving it the ability to repair cylinder groups.  However these patches
were not implemented properly, and their use would only compound your
problem.

Now, there is a patch added to CURRENT that makes cylinder group repair
"one of the standard things that fsck does when running in manual
(non-preen) mode."  So the non-standard '-D' switch is no longer required.

Full details are here:

http://blog.kozubik.com/john_kozubik/2009/05/improving-fsck-with-regard-to-bad-cylinder-groups.html

and it should be noted that if you are not CURRENT, or if you need a 6.x
i386 binary with this functionality immediately, you can find it here:

http://www.kozubik.com/binaries/freebsd/2009-01-00-freebsd_intermediate_fsck_fixes_cylinder_group_maps

This intermediate binary has the working (albeit preliminary) cylinder
group repair code, and unlike the final product WILL require the "old"
'-D' switch to enable it.

-----
John Kozubik - john at kozubik.com - http://www.kozubik.com