Re: Raw Devices: Increased Performance?

Jo Manna wrote:
>
> Steve Long wrote:
> >
> > Jo,
> >
> > I strongly recommend you DO NOT use raw devices. Although you will see
> > a minimal performance gain ( < 10%), you will create a significant
> > increase in administrative overhead managing back-up and recovery as
> > well as considerably more time performing a recovery in the event of a
> > device failure. Economically speaking, it is cheaper to buy more
> > memory and processors to gain considerably more performance than to
> > spend the additional time on administrative tasks (personnel time) when
> > raw devices are used for minimal performance gains.
> >
> > Steve
> > 804-262-6332
> >
> > -----------------------------------------------------------------
>
> Steve,
>
> Thanks for the reply. This is quite interesting. I have previously
> used Sybase and I remember that using Unix File Systems instead of
> Raw Devices was not recommended. Just off the top of me head the
> reasons for this was something like...
>
> ... the Sybase Server being in 'charge' of the actual I/O and if using a
> Unix File System could not guarantee that a 'commit was a commit',
> due to the OS buffering..... and so on.
>
> Obviously we are talking about Oracle here and not Sybase, but I am
> just wondering how Oracle gets around this if at all, or have I missed
> something?
>
> Thanks
> JoJO,
Yes, using raw devices for your datafiles make administration more complex. It does give you some performance gain, < 10% as Steve pointed out. However, you do not have to worry about commit when using file system. Oracle make use of redo logs and rollback segments and ( in case of distributed env. ) two-phase commit to ensure the integrity of your transactions.
Note that if you using Oracle paraller server , you HAVE TO use raw devices. Hope this explain.
Halina Monka Received on Wed Jun 26 1996 - 00:00:00 CEST