Re: Informix, Sybase, Oracle or MS SQL server

tkyte_at_us.oracle.com (Thomas J Kyte) wrote:
>
>- Database does not need to be taken offline,
>hot (online) backups have been part of Oracle since version 6

But Tom, can we use hot backup on UNIX with Oracle database on raw devices?

The impression I got from Michael R. Ault's book "Oracle 7.0 Administration & Management" seems to imply the negative answer to the question above. This is what he said in his book, on page 287.

   "The hot backup differs from the cold backup in that only     sections of the database are backed up at one time. Under     UNIX this will require the use of normal mounted file systems     and not RAW devices."

So, if he is correct, are we required to use filesystems to build Oracle 7.0 database on UNIX if we want hot backup? If so, will this causedata integrity problem? Again, from the same book, on page 18, Michael R. Ault said the following.

   "If you use normal UNIX file devices, there is no guarantee that     all updates will be written to disk in a timely manner. This is     due to the UNIX file buffers. If a system crash should occur     between the time data leaves the Oracle buffers and transits     through the UNIX buffers, data could be lost."

Both hot backup and data integrity are essential to many 24x7 shops. But Michael R. Ault's book seems to imply that hot backup and raw devices are mutually exclusive for Oracle 7.0 on UNIX. Is he right or wrong? Tom, can you clarify these issues? Thanks.

Paul Chen, Ph.D.
Database Consultant
Disclaimer: My opinions only! Received on Sat Apr 27 1996 - 00:00:00 CEST