A friend of mine, Simon Shapiro, has worked for years with the Unix
kernel to overcome the limitations of the sequential search in Unix
directories. He has created a b-tree index as the directory built into
the kernel capable of millions of entries with instantaneous access to
any of them. This would have been great for UniVerse as a type 19 file
or UniData DIR file. Unfortunately his health is failing and this
research project which he hoped to market is dieing with him. Anybody
interested in picking it up?
Scott Richardson wrote:
Stephen hit the nail on the head with the number I have always heard
when talking about optimal I/O threshold target limits for Unix file
systems.
Many years of benchmarking large SMP UNIX architectures and
applications on those seem to confirm those numbers as well. I'd be
willing to say the same about Windows, as a general rule, and
because it simply makes good sense.
Combine file system fragmentation issues, with a little bit too much
indirection, inflicted by huge directories with lots of files, bits and
pieces, and you've got less than desirable I/O performance.
----- Original Message -----
From: "Stephen O'Neal" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, September 30, 2004 11:38 AM
Subject: Re: [U2] [UV] Max Files Per Directory
[EMAIL PROTECTED] wrote:
I've heard some discussions in the past regarding limiting the number of
files per directory to help OPEN performance. Does anyone have any
real-world experience on what a reasonable limit might be on a *nix file
system?
This topic was presented on this at the DM Technical Users Conference.
Our experience shows that it effects the length of time it takes to open a
file. The reason is the length of time it takes to traverse the directory
table to find the file. Literally, we have seen directories (accounts)
with upwards of 4,000 files & dictionaries! We saw improvement in speed
when reduced to the 1,000 entry range.
But this is pail in comparison to keeping files opened thru labeled
common.
We HIGHLY recommend holding files open in common!
FYI,
Steve
Stephen M. O'Neal, CDP & IBM Certified
SWG Services Sales Specialist / Channels & U2
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