Slow Win2K Performance After the Crash
Performance dies on this unnamed admin's Dell server, so Bill helps him trace the problem to driver chaos.
- By Bill Boswell
A Windows 2000 domain controller crashed with a blue
screen of death earlier in the week and since then, it's been really slow.
No, I didn't write down the error code.
Yesterday, the server started beeping constantly and there was an error
message on the screen about a failed drive in the RAID array. This is
a Dell PowerEdge with mirrored drives for the operating system and data.
The RAID controller is a standard Dell PERC controller.
I called Dell tech support and they determined that the drive was functioning
normally. They walked me through regenerating the mirrored set. Right
now, the boot-time PERC controller management console shows a correct
drive configuration with no errors.
But when I restarted after regenerating the mirror, the system hung for
nearly a half hour. I restarted in Safe Mode and as the list of drivers
appeared on the screen, the system hung at the Mup.sys driver. It's done
this consistently ever since.
What's wrong? Do I have a bad drive? What is Mup.sys and why is it hanging?
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Readers: I called Anon and we spent quite a while troubleshooting
this problem. Here's what we did:
First off, I didn't suspect any problem with Mup.sys. This is the driver
for the Multiple UNC Provider, which determines which network client protocol
to use when the target server is specified by a UNC path such as \\Server_Name.
During safe mode boot, the system displays each driver as it is loaded,
so the fact that Mup.sys was the last driver on the screen prior to the
system hang indicated that the problem was with the next driver.
Ordinarily, you can see the drivers loaded during a Safe Mode boot by
looking at a file called Ntbtlog.txt. Because the server was hanging during
safe mode, we decided to boot to the Recovery Console using the Windows
2000 Setup CD. This would also help us determine if there were a problem
with the file system or the mass storage device driver.
As part of the Recovery Console boot process, we loaded a current copy
of the Dell PERC controller driver that we downloaded from Dell's Web
site. We were able to get logged on in the Recovery Console once Anon
figured out the local Administrator password. The Recovery Console uses
the Administrator account from the local SAM, which on a domain controller
is the same account used for Directory Services Restore Mode (DSRM).
In the Recovery Console, we were able to read from and write to the drive
with no slowdown or glitches, so that part of the system seemed to be
working fine. There was no Ntbtlog.txt file though, indicating that the
system was hanging before the file could be written to disk.
At this point, because the PERC controller console showed no problems
and we were able to mount the drive using the latest PERC driver, I wanted
to replace the driver currently on the operating system drive with the
latest driver that we had downloaded. Anon wanted to do some more research
before making changes to the system.
So, we started scouring the Internet looking for other possible causes.
We found quite a few instances of the "hung at Mup.sys" symptom,
but with a variety of fixes. Several administrators solved the problem
by replacing memory. Several others solved it by replacing drive controllers
or by simply moving the controllers to a different slot. One administrator
even replaced both processors.
Then we found a posting by Sean Branham at the Annoyances.org web site.
See the full text of the thread at http://www.annoyances.org/exec/forum/
winxp/t1047532372. Sean correctly determined that the cause of all
these disparate "hung at Mup.sys" failures were actually caused
by problem with the Extended System Configuration Data (ESCD) stored in
the system BIOS.
The ESCD maintains a static list of Plug-and-Play resource allocations.
This avoids recalculating all the allocations at each restart. If the
ESCD gets corrupted, then the operating system cannot assign resources
correctly. Windows makes this resource decision just after it loads the
Mup.sys driver because that's when it loads the Advanced Configuration
and Power Interface (ACPI) drivers.
You can download the (mercifully short) ESCD specification from http://download.microsoft.com/download/1/6/1/161ba512-40e2-4cc9-843a-923143f3456c/escd.rtf.
Once we knew that something in BIOS might be causing the problem, solving
it was a snap. We downloaded the most current firmware revision from Dell's
web site and flashed the BIOS and that was that. (Some motherboards come
with an ESCD rebuild option in CMOS, so it would not be necessary to flash
the BIOS.) The system booted without a hitch and performance was right
back to where it had been before the problems started. If it hadn't been
for Sean's insight, we would have spent time and money replacing the PERC
controller, which unfortunately might well have solved the problem because
replacing the board would have refreshed the ESCD.
It's difficult to determine whether the system crash earlier in the week
caused the ESCD problem or vice-versa, or if some other problem caused
both. At this point, Anon is going to keep an eye on the system and hope
for the best.
I'd like to thank Sean both for solving this tricky problem and for taking
the time to post a detailed account. This was the first time I'd visited
the Annoyances.org web site, and it looks like a great resource.
Hope this helps.
Contributing Editor Bill Boswell, MCSE, is the principal of Bill Boswell Consulting, Inc. He's the author of Inside Windows Server 2003 and Learning Exchange Server 2003 both from Addison Wesley. Bill is also Redmond magazine's "Windows Insider" columnist and a speaker at MCP Magazine's TechMentor Conferences.