From: sysadmin@ph.tn.tudelft.nl (Wouter Smaal)
Newsgroups: comp.unix.wizards
Subject: SUMMARY fsck & reason question
Keywords: fsck & file system inconsistency
Date: 17 Apr 92 09:56:07 GMT
Organization: Delft University of Technology


original questions was:

Is it possible that fsck does not discover disk errors?

responses:
YES..it is possible... Thanks to:
(John F. Haugh II, donne@imec.be [Werner], Alan Rollow and George Michaelson)

I copy the response of John Haugh:
Yes.  FSCK doesn't read the entire disk, only directories, inodes, the
free list, and indirect data blocks.  File data blocks are not read
(thank Ghod) and if your error is there, fsck will never find it.  Also,
fsck only reads filesystems - it completely ignores paging and swapping
space.

Reason of my fsck question is that I have sudden file system inconsistencies
which I have posted to comp.sys.sun.admin. All the responses attended me
on partition overlaps, but I have checked that with dkinfo before I posted 
that question. If I combined the fsck responses (unix.wizards) with the 
comp.sys.sun.admin it is possible (like Sun.nl suggested) that I have a bad 
disk, but maybe that this group have other opinions after reading the reason 
of my fsck question..:
 
From comp.sys.sun.admin Fri Apr 17 11:42:06 1992
Newsgroups: comp.sys.sun.admin
From: sysadmin@ph.tn.tudelft.nl (Wouter Smaal)
Subject: sudden file system inconsistency
Organization: Delft University of Technology
Date: Thu, 16 Apr 1992 13:58:34 GMT

I discovered the last 20 days during normal operation twice an inconsistency
on the same file system. That file system is about 600Mbyte and contains a part 
of our user home partitions. It resists on a secound Sun SMD disk (xy1) with
one Xylogics 450/451 controller. We use SunOS4.1.1 on a Sun4/280 which
is our main fileserver, with 32Mb core.  

On that disk we have two smaller partitons /export (140Mb) and /var (20Mbyte),
which has recently crashed (disappear completely) after interactive fsck ....

There is no reason for file system inconsistency, because there were no 
power interruptions or break downs.  After discovering, I fsck that 
filesystem and answers a lot of questions untill fsck is satisfied.

It srikes me that the file systems (on the same disk) is corrupted suddenly. 
(Few months ago on disk xy0 the root file system disappear (at night)
completely..). Some times the 4/280 reboots after panics... 

Sun.nl thinks there is a problem with disk xy1, but I doubt that, because 
there were no faulty xy1 disk messages in /var/admin. They suggested us 
to run newfs for that file system, but fsck has after repairing no problems 
with that partition. Other alternative of Sun Holland is to replace that 
disk, but I don't believe that the disk is the cause of the "inconsistency" 
problems ..

Are there any "other" suggestions to solve our "inconsistency" problem or
is replacing the disk the best solution?

Regards,


-- 
Wouter Smaal                     E-mail: sysadmin@ph.tn.tudelft.nl  
                                 P-mail: Lorentzweg 1, 2628 CJ Delft, Holland
Department of Applied Physics    V-mail: +31-(0)15-781416
Delft University of Technology   Fax   : +31-(0)15-626740