RE: NT -> Win2K causes performance degradation..

Hi all,

Thanks for the pointers that you have all supplied. Sage advice that they
shouldn't have changed Oracle whilst changing their OS at the same time.

I also did some checking up on the /3GB switch before it was mentioned
(having seen it on here in the past) - Windows 2000 does in fact support a
4gb address space, though the /3GB switch is only appropriate for Windows
2000 Advanced Server and Windows 2000 Datacenter Server - if you use it for
Microsoft Windows 2000 Server - you will lose 1gb of address space! More
info (based on Exchange though) is available here:
http://support.microsoft.com/default.aspx?scid=kb%3Ben-us%3B328882

If we ever find out what the actual cause was, I'll feed it back to the
list. For now we've suggested they roll back the Oracle changes, reassess
performance, and then increase their memory structur! es in steps - assessing
performance along the way. We've also asked about the /3GB switch, and
pagefile sizes - though they think that the rate of their swapping hasn't
increased since the upgrade.

Thanks again!

Mark



-----Original Message-----
Yechiel Adar
Sent: 11 December 2003 14:40
To: Multiple recipients of list ORACLE-L


The /3GB does not work for the simple reason that in W2K you have 3GB as max
address space. At least that what my sysadmin tells me (after checking with
MS).

Yechiel Adar
Mehish
----- Original Message -----
To: Multiple recipients of list ORACLE-L
Sent: Wednesday, December 10, 2003 6:49 PM


Mark,

My guess is, that the new OS re-instated the file system caching.
By default, 41% (yes, it should have been 42%) of physical memory will be
allocated to filesystem caching, as W2K thinks it a fileserver (and domain
controller, web server, print server, etc) un! til you tell it otherwise.

This is much improved in w2k3 server - where you tell it what you want it to
be.

A good sysadmin would have set the OS to "optimize throughput for network
applications" which would have turned off the filesystem caching. Ok, its
only one radio button to select, so an MSCE could set it also.

Surprisingly enough, in W2K Server - changing this setting does not require
a reboot, although I don't know if the changes take effect until after a
system restart. That's not the sort of thing that I usually test, as NT4 had
me trained to reboot afterwards.

the other thing may be, that the boot.ini no longer supports the /3GB or
/PAE switches as Jared mentioned - but that should not cause the symptoms
you are reporting.

hth.

Paul

Mark Leith wrote:
Hi All,

We've been asked a question from one of our clients that I'm a little
stumped on.

They run an OLTP d! atabase (Oracle 8.1.7), and have recently upgraded their
NT machine to Windows 2000, they were running with 2gb of memory, and
upgraded that to 4gb in the process. As they increased physical memory, they
also increased their SGA size & db_block_buffers.

Since they've upgraded they have noticed a significant decrease in
performance (the way it was described to me was "it was 7 out of 10, and is
now 3 out of 10"..).

Has anybody else done a system upgrade of this nature that has caused less
than desirable effects? Any pointers as to what to look at? We've requested
some stats (top wait stats etc.) and I'll feed these back as and when I get
them - but I thought I'd throw this out to you guys in the vague hope
thatsomeone has experienced some relatively similar experiences.

Cheers!

Mark

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