File Corruptions

ghingres@yahoo.co.uk · *nix forums beginner Joined: 14 Dec 2005 Posts: 1

Hiya Nabil,

I'm taking it you're still using Ingres RDBMS and I would hope a
decent file system like Advfs to sit your database tables on ? If so,
what was the OS error posted when Ingres was accessing the table with
corruption ??

1. Have you checked your /var/adm/syslog.dated logs for anything
around the time your dbms first reported problems ?

2. Have you also checked the /var/adm/messages file ?

3. Any emails in root account ??

4. Were there any backup errors ?

If all are clear, depending on the file system you have storing the
data (e.g. Advfs) you could perform some checks (e.g.
/sbin/advfs/verify -a domain)..

If all of this checks out, test out a backup/restore to the tape
drive (to rule out tape drive problems) using the same scripting as for
your dbms backups...

If you've already ruled all of this out - is the restore corruption
limited to ALL backups or only recent.. you could try restoring from
older checkpoints and rolling forward using journals...

Hope this gives something to start looking at...

Gary

Paul Blondel · *nix forums beginner Joined: 13 Dec 2005 Posts: 1

Nabil wrote:

Nabil · *nix forums beginner Joined: 11 Jun 2005 Posts: 12

Our database reported table corruptions. When we tried to recover from
back up, which was a compressed tar file of several database data
files, the uncompress command reported the error - "uncompress: corrupt
input", when consulting with our system administrators, they quickly
pointed in the direction of the database since it reported the
corruption first. Our (DBAs) argument is that true database
corruptions are logical and can only be visible to the database engine,
the OS would never know about true database corruptions such as (bad
leaf pages, dangling pointers, etc..) and the OS utilities would never
know about a native database corruption. Hence we are convinced that
the corruption which was firstly reported by the database was a
physical file corruption due the the I/O subsystem and was *NOT* a
native database corruption and that is why the uncompress also sees it
as a corrupted file.

Also files that we are able to uncompress, we are not able to extract
the datafiles from the uncompressed tar files, in this case, the 'tar
xvf' starts extracting several files then bails out with an error "This
does not look like a tar file, blah blah blah".

Regards,

Nabil Courdy
nabiljc@gmail.com

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