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Re: cross platform performance issue

"Richard Tyc" <Richard_Tyc@sbrc.umanitoba.ca> writes:
> Basically, I have set up a NFS mounted drive on the NT box using OMNI NFS
> Server/Client  from Xlink Technologies.  This drive points to the unix drive
> containing the images. This all works as well.
> The problem seems to be that read_binary() can take several (3-5) seconds to
> read the image file (on the NFS shared drive) even though it is only 138Kb
> (a 128x128 image plus header data) !  I mean , orders of magnitude longer
> than simply copying the file (using NFS) to a local NT drive and than
> reading it, which I am trying to avoid due to large numbers of files needed.
> We have 10Mbit connection directly to the MR system - no routers, bridges
> etc in the way
> Is this an NFS thing or is read_binary  (or OPEN(), READU for that matter)
> have any additional overhead when it comes to network wide file reads ?
> Anyone have better success with other NFS products for NT ?

I just tried a data file using IDL 5.2 on a 10 Mbit/s connection
between a Sun 20 and Dec Alpha.  I got 620 kbyte/sec, this over a line
shared with others in our laboratory.  I simply read the entire
contents of the 12 megabyte file using READU into a byte array.

The next question for you is, what happens when you try READU instead
of READ_BINARY?  Reading any old data should be fine.

I would say that if you are not getting close to 620 kbyte/s or
better, and READ_BINARY is not the culprit, then you truly have a
crummy implementation of NFS on your machine.

Good luck,

Craig B. Markwardt, Ph.D.         EMAIL:    craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response