I received the error message "An error occurred while accessing the DHCP database. Look at the DHCP server event log for more information on this error" when administering DHCP this afternoon.

It took me ages to track down what the problem was - the clue was that I was adding a DHCP reservation; every time I clicked on "Add" I got the error message.

To troubleshoot it I wanted to get an export or dump of all the entries and configuration of DHCP on the server. After a bit of Googling I came across this:

netsh dhcp server <IP address> dump >u:\dhcpdump.txt

But the first time I ran the command I got the output

The following command was not found: dhcp server <IP address> dump

The answer is to issue the command:

netsh add helper dhcpmon.dll

You just have to do it once - and then netsh will know about the DHCP commands you can use.

N.B. <IP address> has to be the IP address of the DHCP server. It can't lookup the server from the hostname

As for my problem; searching for the MAC address I was trying to use highlighted the issue. A single MAC address cannot be reserved twice in a scope. Unfortunately the error message I was getting wasn't explicit enough (and I don't have the rights to look at the logs on the DCs).

I’ve been able to isolate my VMWare BSODs to hard drive issues.

No hard drive has failed – yet, but my first clue was when the Windows crash reports stopped saying “Unknown error” and started saying “Hard drive problem – probably nothing to worry about”  .

That “nothing to worry about” is actually:
ATA Error Count: 38

Which I found out by logging on to the VMWare host and issuing the commands:
smartctl --all /dev/sda
smartctl --all /dev/sdb
as the VMWare installation is RAID 1-ed across both drives

As there isn’t anything wrong with sdb I can safely switch sda for a new hard drive and rebuild the RAID, but that means a few days of little activity on the system.

Is it me, or are you getting BSODs when installing Server 2003 SP2?

I suspect that it’s the VMWare environment that I’m running it under that’s causing the odd problem – how can I get a BSOD under a 2GB 2processor VMWare machine when I don’t get one with a 512MB 1processor VMWare machine?

Host memory?
Host swap?
Host load?
Host hardware?

On the bright note I did discover that if the service pack fails to install and the system is still bootable, the service pack will uninstall itself.

Through experimentation I found that pre-allocating VMWare disks is the best course of action. Sure, you might over allocate disks sizes on the host, but that can save having to restore a from backup when things go wrong.

I recent had the opportunity to experiment with allocating disk or not allocating disks under VMWare. I was under the impression that pre-allocating VMWare disks was the preferred option, but I wanted to know why. But I found out at my cost.

I wanted to build another DC on my test network. A reasonably high spec PC running VMWare was to be the host and a low 512MB RAM, 10GB and SCSI HDD was to be the VMWare machine.

I installed Window Server 2003 Standard Edition, set it up, added it to the domain and was set to go. I thought that installing SP2 would be prudent before making it a DC; and so I set that going.

Unfortunately half hour later, I was greeted with a BSOD and a rather lengthy memory dump. So I reset the VMWare machine and tried to repair Windows. It wasn’t having any of it, and so half hour later I gave up and did a complete re-install.

Thinking something just went wrong with the first attempt, I updated the drivers before installing SP2 for the second time. The drivers were up to date, so I installed SP2, and thirty minutes latter was greeted by another BSOD.

I was getting rather fed up of this. So I deleted the VMWare hard drive and created a new one – all allocated – for the third attempt.

This time it worked. No BSODs and now one happy DC!