Re: Oracle datafiles across an NFS

In article <430pl9$9b_at_ivu.ivu-berlin.de>, tk_at_ivu-berlin.de says...
>
>Mike Cuppett (cuppettm_at_richmond.infi.net) wrote:
>: Is anyone running Oracle in a manner in which a datafile resides on a
>: separate computer via a NFS?
>
>We did it and got time outs ('media failure') at peak times.
>
>If you decide to create a rollback segment on nfs prepare to
>recreate your database...
>
>--
>--------------------------------------------------------------------
>Thomas Keul, IVU GmbH tk_at_ivu-berlin.de
>Bundesallee 88 tel +49 30 85906 451
>12161 Berlin, Germany fax +49 30 85906 444
Thomas is exactly correct. NFS is a stateless environment. TORACCLE requires a write verify (a true write verify) from the system call. On NFS the NFS daemon intercepts the write call and returns success WITHOUT verification thhat the write occurred on the remote server. Thus, PREPARE YE TO BE DOWN.. At some point when the network is busy ORACLE will get a write verify and then attempt to read what it thinks is there. But the write won't have occurred yet. If by some chance the two calls go to different daemons we may have an inconsistent state and ORACLE will tell you this condition with a most virile message.

Marc E. Marchioli	marcm_at_computek.net
The DataBase Group	Dallas, TX 75204