Re: What is a good blocksize to use.

"Paul Brewer" <paul_at_paul.brewers.org.uk> wrote in message news:3d90dc3c_2_at_mk-nntp-1.news.uk.worldonline.com...
> "Ben Brugman" <benbrugman_at_onbekend.nl> wrote in message
> news:3d90781f.26180500_at_news.nl.uu.net...
> > For a transactional machine, where most rows contain a few hundred
> > byte. Assume a RAID (1/0) device as storage medium.
> >
> > What is a good blocksize, and why ?
> >
> > What are the effects of going smaller in blocksize ?
> > What are the effects of going larger in blocksize ?
> >
> > ben brugman
> > Ben Brugman
>
> Ben,
>
> Insufficient input. Go for 8K, or provide more detail.

I do understand that there is not sufficient input. On purpose the question left this open.
I am trying to get some insight in advantages of larger and off smaller blocksizes.
Especcially with RAID divises and going towards 64 K stripes and larger, I would like to know how data is handled specifically if blocksizes do not match.

Most go for the answer : Use the same blocksize and bigger is better.

But bigger blocks effectively fill the cache faster. If only a small amount of data is used from each block, a double blocksize allows only half the amount of blocks in cache and (depending) only half the amount of usefull data.

Small blocks are often handled by the hardware diskcache so there is no latency for disk rotation or head movement.

But I do not know how small (Oracle blocks) are handled if OS blocks are larger and RAID blocks are even more larger. And would like to know.

ben Received on Wed Sep 25 2002 - 15:55:02 CDT