Office Power Cut

A fairly interesting and successful job the other day: The client called at 9:30 to say that, essentially, nothing was working in the office. They had come in, put the kettle on and tripped the main CB cutting power to everything! Despite rebooting the router, PCs and server, they were unable to access the internet or shared files.

First job when we arrived onsite around 10 O’clock was to re-establish internet connectivity. Grabbing a PC and running ‘ipconfig /all’ showed that it had acquired a 169.254.x.x address through APIPA, meaning that there was no DHCP server available. Plugging a laptop into the BT Hub showed that DHCP was working, so the explanation was that the PCs had rebooted while the hub was rebooting and thus couldn’t acquire proper IP addresses. Rebooting all the PCs again (or running ipconfig /renew) fixed this.

With the IP network working and internet access restored, we turned our attention to the server which was still inaccessible. Plugging a monitor into the server (a Windows XP machine) showed the dreaded ‘Windows XP could not start because the following file is missing or corrupt: \WINDOWS\SYSTEM32\CONFIG\SYSTEM’ message. Clearly some data corruption had occurred when the power was lost.

The config\system file in window is the main registry hive that contains all the configuration information windows needs to start and run. Without it windows can’t get off the ground. Luckily it is possible to extract a backup copy of this file as described in MS KB 307545. (In fact the article is unnecessarily long-winded: we just booted to a liveCD and copied the config file directly across from System Volume Information).

With that completed the server booted fine. A run of checkdisk identified some file system corruption, so chkdsk /r was run to clean this up. Just under 1.5 hours from office chaos to all systems restored. The moral of the story? Install an Uninterruptible Power Supply and make sure it works!

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