Re: raw devices

Hi,

    You may be suffering from a false sense of security when it comes to RAW devices. It doesn't matter how smart the RDBMS is the OS can take control away from the RDBMS without the RDBMS ever knowing about it. In fact when using an LVM or hardware RAID there is a good chance that all of your I/O is buffered -- including writes to raw devices.

    In either case the answer is a UPS and RAID using mirroring or parity. The former will protect you from a power failure and the latter will protect you against a disk crash. Finally, in order to eliminate the probability of getting nailed by a server failure go for a system that can deliver 99.999% uptime.

regards
Jerry Gitomer

DM wrote in message <37B977FB.F2517CE_at_auto.com>...
>Hello,
>I know that this was part of a previous thread, but the thread
didn;t
>cover the database integrity.
>Somebody asked if you should use cooked or raw devices with
Oracle, for
>speed and integrity reasons.
>From what I know, If you use cooked devices on unix, the file
system
>will try to cache as much as it can and the data you commit will
be
>"commited" in the fs cache and flushed from time to time to
disk. This
>means that if the server crashes you will probably loose
non-flushed
>data with the database engine not being aware of the loss(so no
rollback
>for you).
>Am I wrong, is Oracle smart enough to detect this situation?
>Thanks
>Max Mera
>
Received on Tue Aug 17 1999 - 12:13:33 CDT