Re: NT read request size

NT reads one cluster @ a time (that is why clusters exist). You already know how to find your cluster size.
NT reads a cluster and creates in memory page(s) (page size is always 4k). Depending on the cluster size there might be more cluster reads to populate the page (e.g.. 1k cluster and 4k page). In your case there will be 64k/4k = 16 pages created and put in real memory when a cluster is read and before the next cluster is to be read. This is assuming no paging out and using virtual memory. Read NT res kit for more info.

Stilian

Patricia Schorsch wrote:
>
> Thanks for everyone's input on this. I have come to the conclusion that
> know one knows the answer - except Microsoft who is not saying anywhere I
> can find - back to Powell's Technical. I posted it in the NT forum and
> haven't got an answer. I am not talking about how much NT will store in a
> cluster - just how much it will read at once before it passes the info on
> and goes after the next chunk of data on the drive.
>
> If it is dependent on formatting clusters and how NT stores the info then I
> would like to know. My drive is not formatted at 64K clusters. I don't
> want to know it for my current system. I want to know it for planning a
> system.
>
> That is my understanding of the DB_FILE_MULTIBLOCK_READ_COUNT *
> DB_BLOCK_SIZE = the most your OS will read at a time. That it has nothing
> to do with the drive formatted cluster size. I could be totally wrong
> though.
>
> Patricia Schorsch 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 Thu Mar 11 1999 - 16:08:47 CST