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Re: S-plus slow with remote .Data directory

To: <s-news@lists.biostat.wustl.edu>
Subject: Re: S-plus slow with remote .Data directory
From: "David Smith" <dsmith@insightful.com>
Date: Mon, 26 Nov 2001 15:43:15 -0800
Importance: Normal
In-reply-to: <54C6B7921595FF40AB81D151FDFB7F4F01D1C0@fps01.proteom.com>
> It would be a help to me if David could expand on his knowledge that
> remote .Data files "can slow down S-PLUS on some networks" here or on
> the S-Plus website, which seems not to mention this.

I was avoiding all the gory details (mostly out of personal risk-aversion
since I'm no expert on the subtleties of network performance) but since you
ask...

The problem relates to the rate at which S-PLUS flushes buffered output when
writing objects to disk (this occurs at the lowest level of the object
database code).  S-PLUS 6 flushes the output more often than S-PLUS 2000;
for example, the row names of a data frame were essentially written
one-at-a-time instead of in one large chunk.  It doesn't make much
difference when .Data is on a local disk, but we discovered after release
(thanks to reports from users) that this slowed things down when writing
across networks without client-side buffering.  For S-PLUS 6.1 we've
reverted to the old way of doing things, and early tests indicates that it
speeds up writing large objects to remote disks quite a bit.

# David Smith

--
David M Smith <dsmith@insightful.com>
S-PLUS Product Marketing Manager, Insightful Corp, Seattle WA
Tel: +1 (206) 283 8802 x360
Fax: +1 (206) 283 0347

Insightful Corporation provides analytical solutions leveraging
S-PLUS, StatServer, S-PLUS Analytic Server and consulting services.
See www.insightful.com for details.



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