Also, most terminal servers support analog modems or come with an internal analog modem; even if all hell breaks loose and the network goes down, you can still gain access to the very components needed to bring that access back. It's the best way to ensure that your infrastructure can be fixed during planned or unplanned downtime -- short of setting up cots and a hotplate in the server room.
A serial terminal server of sufficient size should be part of every IT infrastructure, but it's especially useful for unattended remote sites. It shouldn't even be a question -- it should be mandatory, right along with a locking rack or server room and environmental monitors.
That said, I'm always dismayed when I see a data center wholly lacking in serial console connections. These ports exist for a reason, and not taking advantage of them -- especially when it's so cheap to do so -- is perplexing at best. Even if you buy brand-spanking-new terminal servers, they're still not terribly expensive and offer plenty of bang for the buck.
To some, it may seem odd that I'm singing the praises of one of the oldest forms of computer communication: the lowly serial port. Why bother with such Paleolithic technology when we have all kinds of bandwidth, redundant this and that, and disaster recovery plans sitting on the bookshelf?
Because there are guaranteed to be occasions when having a remotely accessible 9600/8-N-1 serial connection to a piece of IT gear saves mountains of time, effort, and headaches on everyone's part -- and that should be all the justification necessary.
This story, "Terminal servers -- saving your bacon, one console at a time," was originally published at InfoWorld.com. Read more of Paul Venezia's The Deep End blog at InfoWorld.com.