Re: UFS file system problem in either stable or current

2003-11-02 Thread Dan Strick
On Sun, 2 Nov 2003, Valentin Nechayev wrote:
 Wed, Oct 22, 2003 at 03:14:33, strick (Dan Strick) wrote about UFS file
 system problem in either stable or current:
 DS There seems to be an inconsistency between release 4.9-RC and 5.1 ufs
 DS support.  If I fsck the same ufs (type 1 of course) file system on
 DS both releases, each claims that the other has left incorrect
 DS summary data in the superblock.  Presumably only one can be correct.
 DS I just don't know which to blame.

 Does this require explicit fsck?
 I have dual-booting between 4.9-release (and all previous 4.* releases earlier)
 and 5.1 (of 20030526) with shared disks and boot checking required in fstab;
 sometimes one of them crash and forced checking is made; neither 4.* nor 5.1
 claims superblock is bad.

You wouldn't notice after a crash.  The incompatibility turns out to be
the location and perhaps details of the summary information (e.g. number
of free blocks) in the superblock.  This does not affect the integrity of
the file system.  It does affect the output of the df command.

The first time you run fsck on a file system after modifying it
when running the other operating system, fsck will probably find
inconsistent super block summary data.  fsck -p will correct it
without asking (and might not even say much about it).

I recently read something in one of the FreeBSD newsgroups that
suggests that this incompatibility between 4.x and 5.x has in some
sense been corrected in -current.  I don't know any details.

See also:

http://www.freebsd.org/cgi/getmsg.cgi?fetch=446102+449665+/usr/local/www/db/text/2003/freebsd-current/20031102.freebsd-current

Dan Strick
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Re: UFS file system problem in either stable or current

2003-10-28 Thread Dan Strick
On Wed, 22 Oct 2003 06:23:20 -0500, Peter Schultz wrote:

 Dan Strick wrote:
  There seems to be an inconsistency between release 4.9-RC and 5.1 ufs
  support.  If I fsck the same ufs (type 1 of course) file system on
  both releases, each claims that the other has left incorrect
  summary data in the superblock.  Presumably only one can be correct.
  I just don't know which to blame.
  ...

 There is no problem AFAIK, you just have to fsck with the matching 
 executable.  A lot has changed with FreeBSD 5, spend some time with the 
 -current archive and you will learn more.  I'm sure you noticed how your 
 findings are consistently inconsistent.

Thanks for the pointer.  I eventually found at least part of the
discussion in the -current archive.  I interpret the discussion as
follows:

The 5.x UFS1 file system turns out to be slightly incompatible with
earlier UFS file systems.  The problem is only that it keeps the
summary data in a different location in the superblock, but that is
sufficient to make the file systems incompatible.  There seems to be
no interest in making them compatible.

Suggestion: if FreeBSD 5 used a different clean flag and FreeBSD 4/5
always cleared the other's clean flag whenever they rewrote a superblock,
the file systems would automatically be refscked whenever you switched
between operating systems but not after a normal reboot.

Dan Strick
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UFS file system problem in either stable or current

2003-10-22 Thread Dan Strick
There seems to be an inconsistency between release 4.9-RC and 5.1 ufs
support.  If I fsck the same ufs (type 1 of course) file system on
both releases, each claims that the other has left incorrect
summary data in the superblock.  Presumably only one can be correct.
I just don't know which to blame.

I couldn't find a FreeBSD problem report about bad summary data.
I will submit one, but since FreeBSD 4.9 is about to be released,
someone might like to check this out.

I happen to have multiple FreeBSD operating systems installed on
the same computer.  This might also be an issue if you move an
external disk between computers.  I don't know if the problem shows
up on all file systems.  It seems to happen on all the half dozen
or so of the file systems that my 4.9-RCx and 5.1 systems share.

Dan Strick
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