Re: Raw Devices: Increased Performance?

answers_at_ix.netcom.com(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.

This is an endless discussion.....

What I cannot understand, however, is the always brought up argument about the "administrative overhead".

At our site, we constantly use raw devices and we had a performance gain of 20 %; this is because our file-cache is used heavily by small reports, sometimes dozends per minute.

Back to the topic, where is the administrative overhead ? When you need a new datafile, then you have to define a file in a filesystem or, using raw devices, a slice of disk; in both scenarios you have to make sure that you have enough free space on your system.

The same goes, IMHO, in a recovery scenario - or what did I miss here ?

Regarding backup, it is simply a question of your backup procedure - if you use cpio or tar, you surely are out of luck...

>Steve
>804-262-6332

Willy Klotz

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