Re: A bad block analyzer

In article <1994Aug24.141308.21768_at_nntpxfer.psi.com>, Scott Mattes <Mattes_at_navsealog.i-net.com> writes:
>
> I ended up doing a cold start early this a.m. and reloading the instance from
> an export. What started the whole thing was a bad block that prevented us from
> reading some of the data in one table (couldn't select it, couldn't export the
> table). Now my boss wants to know if the problem is hardware or software
> (Oracle wrote something, somehow, that it can't read - there was a user on
> doing some weird key sequences about the time the first error msgs came up).
>
> Is there some software, on any Oracle platform, for analyzing a bad block to
> see if it is really bad or just bad data that Oracle can't read? Next, does
> this exist on VM. BTW, I know about DSF on VM/CMS.
>
> Thanks.

Try copying the file(s) to another disk or tape and you should see a hardware read error if its a bad block. If it's a bad block in an index then you can simply drop and recreate the index somewhere else. If it's data then you will have to recover the database (or that table) to a point in time.

Oracle (in my VMS environment) seems to be very fragile with regard to I/O errors. YES, I know an I/O error is BAD but modern disk controllers actually can detect blocks that are starting to go bad and will replace them with spare blocks on the track and simply change the virtual block allocations for the affected file. Oracle just gets errors on these replaced blocks for some reason.

-- 

Bruce...        pihlab_at_cbr.hhcs.gov.au

*******************************************************************
* Bruce Pihlamae  --  Database Administration                     *
* Commonwealth Department of Human Services and Health            *
* Canberra, ACT, Australia                        (W) 06-289-7056 *
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* These are my own thoughts and opinions, few that I have.        *
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