FASTIO_READ vs IRP_MJ_READ

Can someone please tell me what governs these calls. We have software
that acessess a file share on the server and if it uses IRP_MJ_READ it
is terribly slow. I understand why it is slow I just do not understand
what governs which call will be used.

Can anyone Help?

<(E-Mail Removed)> wrote...
>Can someone please tell me what governs these calls. We have software that
>acessess a file share on the server and if it uses >IRP_MJ_READ it is
>terribly slow. I understand why it is slow I just do not understand what
>governs which call will be used.

>Can anyone Help?

What controls it is whether or not the data is in the file system cache or
not. Cached data is read by a FASTIO_READ while non-cached data is a slower
IRP_MJ_READ. Whenever a file system driver returns a Fast I/O command
status of FALSE, the I/O Manager falls back on the IRP-based request path.

http://www.windowsitpro.com/Windows/...95/pg/2/2.html

--
Todd J Heron, MCSE
Windows Server 2003/2000/NT; CCA
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Todd thanks for the reply - I sort of knew that bit already - my
mistake I should have been more explicit.

In a client - server file share scenario which file system should we be
looking at? The reason I ask is we have two setups running WinXP
Clients and Win2003 Servers. One uses FASTIO_READ while the other uses
IRP_MJ_READ. This obviously causes the software to run significantly
slower and while we know what the issue is we don't know how to change
the setup so the FASTIO_READ is used or even if it is possible to
control this at all?