Re: Multiple DB writers vs. I/O slaves

Nuno Souto <nsouto_at_nsw.bigpond.net.au.nospam> wrote:
>
>thanks folks.
>
>so if I had say, buffer KEEP with 4 LRU, buffer RECYCLE with 4 LRU and
>buffer DEFAULT with 4 LRU and a 4CPU box, what should I try:
>
>3 DBWRs (one for each of the buffer caches
>or
>4 DBWRs (one for each of the 4 LRU)
>?
>
>I can't make up my mind and "suck and see" is out of the question.

I'd be surprised if you ever needed more than a single DBWR on a 4 CPU machine in 8i with async I/O.

I found 2 DBWRs sufficient for shifting a sustained write rate of more than 13,000 blocks/second (8kB blocks).

Make sure you tune your kernel parameters for async I/O.

-- 
Andrew Mobbs - http://www.chiark.greenend.org.uk/~andrewm/