Re: Q: does DirectIO on windows is supported on file systems ?

On 6/23/05, Sunil Bhola <oraclebhola_at_yahoo.com> wrote:
> Hi Gonen,
>
> Direct I/O is depends on the operating system, you are using. Like in
> UNIX/LUINUX/SOLARIS, you can use Direct I/O or File System's Buffer Cache.
> In Windows there is nothing like O/S Buffer Cache. So you cannot use it. Yes
> you can use Direct I/O in UNIX/LINUX/SOLARIS, for this you need to modify
> the file system buffer cache.
>
> In the Windows it uses DIRECT I/O, means the blocks are read directly from
> the disk and passes to the application that is required this.
>
> So when you are creating a Database in Windows you can use any block size.
> But in UNIX/LINUX/SOLARIS you have to consider your FILE SYSTEM BUFFER
> CACHE. Say your o/s file system buffer cache is 4k, then there is no use to
> define the block size of 8k, as for any single i/o the o/s has to send the
> request twice.
>
> Regards,
>
> Sunil Bhola
>
> Oracle_Expert, Moderator

Sunil,

Where did you get the idea that MS win32 operating systems had no filesystem buffer cache?

(It is reccommended to turn this functionality off for running Oracle, but if exists by default).

Paul

http://www.microsoft.com/technet/prodtechnol/windows2000serv/maintain/optimize/wperfch7.mspx

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