Re: NT read request size

NT cluster sizes depend on the type of the partition (FAT or NTFS) and its size.
Since FAT is strongly suggested NOT to be used as a DB data partition I will just list the NTFS
ratios.
These are the default values

part. size cluster size

0 -  512 M    - 1/2k
513 - 1024 M  - 1k
1 - 2 G       - 2k
2 - 4 G       - 4k
4 - 8 G       - 8k
8 - 16 G      - 16k
16 - 32G      32k
 > 32G         64k

The cluster size is set when a partition is NTFS formatted. One can choose from 1/2 to 4k or the default value for cluster size when formatting a partition with Disk Administrator.

Stilian

Patricia Schorsch wrote:
>
> Does the io size depend on what cluster size you format the drive? I know with
> UNIX the read request is 64kb so with DB_BLOCK_SIZE set at 4kb you can set
> DB_FILE_MULTIBLOCK_READ_COUNT to 16. But I can't find in any documentation what
> the most amount NT reads in a single read request would be. If it is variable
> (64K-512 bytes) then how do I set it or find out what it is set at?
>
> I could turn on my system monitor and just do huge reads and see what the average
> read is but that is kind of backwards and not going to be accurate.
>
> Denny Koovakattu wrote:
>
> > To my knowledge the io size is (64K - 512bytes) for NT. Anyway with 4K you may
> > have to set the multiblock read count to 15. ( Even if you set it to 16, it's
> > changed back to 15. ) HTH.
> >
> > Denny
> >
> > In article <36E61FCA.97B86FA4_at_aol.com>,
> > Patricia Schorsch <pschorsch_at_aol.com> wrote:
> > > Does anyone know what the Windows NT 4.0 read request size is or how to
> > > calculate it if it is drive/cluster size dependent? I am trying to
> > > figure out what the maximum DB_FILE_MULTIBLOCK_READ_COUNT can be with a
> > > 4KB DB_BLOCK_SIZE.
> > >
> > > Thanks,
> > >
> > > Patty Schorsch
> > >
Received on Wed Mar 10 1999 - 13:55:34 CST