What To Do When the Server Doesn't Serve

Brett Lymn

Not that long ago when a server stopped serving files, most people would ask when the machine would be back on the air, smile ruefully, and wait patiently for their files to reappear on their network drives. The excuse "sorry, I cannot tell you that because the computer is down" was accepted, and people would call back later for the information. Those were the days. Servers are now expected to reliably serve up files 24 hours a day, 7 days a week. Downtime no longer is an inconvenience -- it costs money. If your Web server is down because of a file server failure, then people will rarely wait patiently for the Web server to come back on line. They will take their business, and their money, elsewhere. Because of this, there has been a lot of focus placed on building systems that do not rely on a single point of failure, so that even if one component fails, the system as a whole will continue functioning.

Hardware designers have been working at this for some time, and it shows in the latest machines that have dual this, hot-swap that, to provide the ability to ride out a hardware failure and repair the machine without requiring it to be shut down. Of course, the operating systems that sit on top of this hardware have been modified to exploit the new hardware features to provide resiliency in the face of failures. The problem now is that modern machines rarely live in isolation. They are typically networked to other machines with the result that all your hardware and software redundancy grinds to a halt when the file server goes down.