March 27, 1996
Subject: Re: ORA-01555 snapshot too old? / NetWare-Database crashes
References: <>

Friedel Hosenfeld  writes:

>Hi,					Kiel, 27-MAR-1996

>I am experiencing a strange problem. One of our databases
>is a Oracle7 ( running on a Novell Netware (3.11)
>server. We must use that old release because of some
>compability reasons.

>Since some days ago the database export doesn't work,
>giving instead the message "ORA-01555: snapshot too old (rollback segment
>too small)".

>When I retrieve some tables, I get at some point (some particular
>users) that message. Some other users are fine.

>Very often - when I shut down and restart the database -
>not only the database but the whole NetWare-Server crashes.
>Sometimes the database crashes without any user action.

>It's a very small database. I enlarged the tablespaces and
>rollback segments but that didn't change the situation.

>In the manual 4 reasons can be found, but only
>the first two could be responsible in my case:
>1. Insufficient Rollback Segments
>   -> but I increased them
>2. Corrupted Rollback Segment

>Because of the frequent crashes, I think that might be
>the reason. How can I check that? Is there somebody
>with experiences with that error message?

>I will probably call the hotline but any hints are

>Thank you,
> friedel

>    Friedel Hosenfeld
>Ecosystem Research Centre  
> Schauenburger Str. 112		          
>  D-24118 Kiel *  FRG                         blue in the face?


What you found in your manual may not fully explain the problems you have 
been having. The most likely cause IS that your rollback segments are too 
small. Specify larger INITAL and/or NEXT EXTENT sizes for your rollback 
segments. Considering that only some users get the error message, it seems 
that those users attached to that segment get the error, while the users 
attached to other segments do not get the error. Also be sure to set the 
OPTIMAL parameter of the rollback segment (if you are using Oracle7).

Another problem could be caused while using Trusted ORACLE. If your 
interval between checkpoints is too small in a secondary database, you
can get this error. Oracle recommends decreasing the value of the
LOG_CHECKPOINT_TIMEOUT parameter in your "init.ora" file.

As to your system crashing, I can't help you there. You could have a
legitimate bug.

If you are worried about corrupted rollback segments, then drop and
recreate them as soon as possible!

Good luck.

-Ari Kaplan
Independent Oracle DBA Consultant

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