Re: i/o parameters on oracle and sun

Thanks for your reply,
Is it not true that having a large multiblock read count will effect the cost based optimizer into issuing full table scans as opposed to using the indexes? Also I read a white paper that stated that the strip width = interlace size * number of drives in the array = max i/o size

example max i/o = 128 K and # drives in the array = 4 stripe width = 128 K = interlace size 32 k * drives in array 4 = 128 k max i/o
or
max i/o = 1024 K and # drives in the array = 4 stripe width = 1024k = interlace size 256 k * drives in array 4 = 1024 k max i/o

In article <3A62F300.6806_at_yahoo.com>,
  connor_mcdonald_at_yahoo.com wrote:
> rkatofiasc_at_classifiedventures.com wrote:
> >
> > We are moving our data warehouse to a sun 4500 6X6 with 2 sun 5200
> > (18G) drive arrays. Can you gurus give me some thoughts on what
 would
> > be the optimal parameter sizes? I am looking for the db_block_size,
> > strip width size, db_multiblock_size. I think we are leaning
 towards a
> > 16 K block size. The file system will my managed using Veritas for
> > Oracle (1+ 0 raid or 0+1). It seems the default is 16k for the strip
> > width. Should the strip width change based on what the file is used
> > for i.e data, index or logs. The data warehouse uses a
 multidimensional
> > architecture, which minimize full table scans by using bitmapped
> > indexes on the fact tables. I was hoping that someone might be
 working
> > on a similar system and can give me some feedback.
> >
> > Thanks Rob
> >
> > Sent via Deja.com
> > http://www.deja.com/
>
> Without full investigation into requirements etc...
>
> block size: 8k if on file systems, possibly 16k if on raw
> multiblock read count = large as possible which means you probably
 want
> to increase the maxphys setting in /etc/system, eg if maxphys = 256k,
> and block size = 8k, then multi-read-count should be 32 (256k/8k)
> Stripes typically same a single multiblock read
>
> But rest assured, hoping that things will work out well just be
 setting
> a few parameters is a sure fire way to problems...
>
> HTH
> Connor
> --
> ===========================================
> Connor McDonald
> http://www.oracledba.co.uk (mirrored at
> http://www.oradba.freeserve.co.uk)
>
> "Some days you're the pigeon, some days you're the statue"
>

Sent via Deja.com
http://www.deja.com/ Received on Mon Jan 15 2001 - 15:44:39 CST