Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!apollo!ced
From: ced@apollo.HP.COM (Carl Davidson)
Newsgroups: comp.sys.apollo
Subject: Re: Can anyone help with a salvol problem?
Message-ID: <4c83a20b.20b6d@apollo.HP.COM>
Date: 30 Aug 90 19:52:00 GMT
References: <1990Aug30.152435.23881@watdragon.waterloo.edu>
Sender: root@apollo.HP.COM
Lines: 81

From article <1990Aug30.152435.23881@watdragon.waterloo.edu>, by dvadura@watdragon.waterloo.edu (Dennis Vadura):
> Recently we had a bad electrical storm here and it nocked out one of our
> DN3500's.  When rebooting it attempts to run salvol and fails.  I have
> managed to boot the node over the network and to forcibly mount it's disk.
> I have dumped the contents of it's disk (using wbak) to another node and
> will invol and restore the files.  I expect this to remove the file system
> errors reported by salvol (can anyone confirm this?).
> 

Dennis,

Presuming that the drive hardware itself was not damaged, and it doesn't appear
from the output of salvol that it was, invol should be able to return your 
drive to a usable state, although as you expect all data will be erased.

When you run invol, you should be sure to check the bad spot list that is on 
the media against the hard copy list that came with the drive. On DN3500s, 
the bad spot list for the drive is printed on top of the drive itself, and is
generally, although not always, only a few items -- maybe a dozen or so.

It appears that the electrical storm caused the drive to scribble random
garbage over the surface of the drive media. Salvol, when attempting to 
repair the disk, sees this scribbling as bad formatting (chk_hdr is, I assume, 
the internal salvol routine that validates the disk block header) and flags
the blocks to be replaced. Unfortunately, in the second pass salvol runs out
of space to store the bad blocks in and so can't complete its job. It's just as
well, really, because it's unlikely that the disk media is actually bad here
and you don't really want to throw all those bnlocks away unnecessarily.

>
> Also, does anyone know what if anything can be done about the following output
> from salvol (attached below).
> 
> -thanks
> -dennis
> ----
> $ /etc/salvol -c w0:0 -f
> 
> 
> Salvol, revision 10.2, October 12, 1989  2:55:07 am
> 
> 
>     Preparing file list...
> 
>     Salvaging...  % complete
>         20
>     (chk_hdr) page should be: 37 but is: 112
>
>      < many lines of similar errors deleted>
>
>         40
>         60
>         80
> 
> 
>     Verifying reference counts...
> 
> 115 multiply allocated blocks were found
> 
> Starting second Pass...
>     Preparing file list...
> 
>     Looking for Mutiply Allocated Blocks
>         20
> Internal Error: hash table for bad daddrs is full, too many MAB's or header erro
> rs.
> 
> RUN ABORTED
> -- 

There really isn't much you can do with this output except go on and invol 
the disk. Any repairs attempted by hand would be difficult at best. It's better
to let invol straighten things out itself.

Regards,
Carl

Carl Davidson  (508) 256-6600 x4361    | In the High and Far-Off Time, the
The Apollo Systems Divison of          | Elephant, Oh Best Beloved, had no
The Hewlett-Packard Company            | trunk.
DOMAIN: ced@apollo.HP.COM              |  -- Rudyard Kipling, Just So Stories