Moving or Copying files too Server takes Forever or Network timeout

Posted at 3:18:02 PM in Recovery (44)

Recently had a server with a brand new drive upgrade. While the server was down, everyone continued using the internet through our Comcast business class router.  Being the wonderful IT guy that I am, naturally I think I'm the only one who's right and installation teams are stupid and just do what they were taught in school, no matter how wrong it is.

The server is a Windows 2000 Domain with only one domain controller. Active Directory Services installed, DNS and DHCP services also utilized (pretty much basic domain controller setup). After the upgraded drive was installed, which should have given us huge performance improvements, the server started hanging about every 15 to 30 seconds. It would freeze then start again. Everything was sticking. During the normal course of working on the server, opening dialog boxes such as Network Properties and Control Panel would click, hang for several seconds then open and continue for another 15 to 30 seconds before it would hang again. This really was quite annoying. There was no processes eating up CPU and the memory usage was well below available RAM. There was also, no system or application log errors that would account for the problem.

Our first really big indication came when moving files back to the server. We have several files that are in excess of 300MB. All of the files would start out fast, then hang and take forever to finish. Large files would hang and disconnect with a network error. The certainly seemed like a network issue, but we didn't change anything on the network. Ping times were all less that 10 msec. So I started suspecting the new hard drive was the problem, but it wasn't.

Active Directory Services depends on all clients including itself to look to the DC (domain controller) for DNS activity. This is mostly for svr records that don't play a role in the internet, but also for general client location. If the clients are not looking to the DC for DNS activity, the network gets flooded with requests looking for a DC to answer and there isn't one to be found. The entire network falls apart. I know this is probably and over simplified description and it may not be 100% accurate, but the basic concept is, if the clients (including the server itself) are not looking to the DC for DNS look up, then the network will fall apart. 

When the server was down for the drive image and installation, all the workstations picked up new IP addresses from the Comcast Router. Normally, if there are 2 DHCP servers on a network, one will fail to allow the other to assign addresses. Occasionally, both will fail in favor of the other. My experience has been that Microsoft's DHCP will will fail. Why is this important? It's not he DNS server. DHCP assigns the information to the clients that tell it where to find the DNS server, among other things. When the workstations (clients) got the IP information from the DHCP server on the Comcast router, it pointed to itself for DNS services and thus all the clients were spraying lookups everywhere but the right place. To temporarily fix this on the workstation the files were being transferred from, I set a static IP address with the correct DNS information.

My arrogance at the beginning comes only because Comcast setup their router. Of course, they it up with the DHCP services started because that's what they are taught to do. In most residential situations, this is acceptable, but in a business environment having the router assign addresses is a catastrophe in a Active Directory network. A lot of my most irritating problems come from people who can't think outside the box or don't know how to. That being said... I have my own box that I'm stuck in.

Written by Leonard Rogers on Tuesday, June 26, 2012 | Comments (0)