Mark D Powell wrote:
>
> I do not claim to be familiar with the details of the NTFS file system
> structure but if I remember from the manuals that covered formatting my
> new harddrive back in the days when you upgraded PC rather than buy new
> ones the 512k chunk on disk was the device sector size. The OS
> however, reads and writes multiple secotrs at a time. This grouping of
> sectors was called a cluster and generally was 2k, 4k, or 8k worth of
> sectors at a time. On any other system except Windows the cluster size
> would be called the block size. The cluster size dedended on the
> size/mdoel of the disk drive and how it was partitioned.
>
> If the OS block size is 4K the two OS IO are required for every Oracle
> IO and 25% of the IO is wasted since it is not part of the requested
> Oralce block(s). This would be bad. If on the other hand the OS IO
> size is 6k then the 6k size choice for Oracle was probably a good one
> in the past. Since the manuals refer to Oracle only officially
> supporting 4k, 8k, 16k, and 32k you may want to determine what the real
> OS IO size is and match the database to it.
>
> -- Mark D Powell --
I suppose using a "non-power-of-two" blocksize does give you access to
an additional cache...although I would imagine its a pretty specialist
requirement to have a database that explictll needs that extra cache :-)
--
Connor McDonald
Co-author: "Mastering Oracle PL/SQL - Practical Solutions"
Co-author: "Oracle Insight - Tales of the OakTable"
web: http://www.oracledba.co.uk
web: http://www.oaktable.net
email: connor_mcdonald_at_yahoo.com
"GIVE a man a fish and he will eat for a day. But TEACH him how to fish,
and...he will sit in a boat and drink beer all day"
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Received on Mon Apr 04 2005 - 06:35:23 CDT
