Over the years, I've used a wide variety of systems to access and manage the servers in the various data centers I've worked in. At the turn of the century we used CRT monitors and standard keyboards and mice on rack shelves with single user analog KVM (keyboard, video, Mouse) switches. Today most of the mid-market data centers I work in have pull out LCD consoles with touchpads in each rack, but I'm starting to think it's time for a big change.
There has been some progress in the KVM switch arena as we've transitioned from really stupid electro-mechanical switches to analog switches that emulate the keyboard and mouse signals on all their ports so servers won't forget they had a mouse connected, which of course means we need another reboot. Today's KVMs use CAT5 cables so we don't have to snake the big stiff VGA-PS/2 cables around the servers. Of course, since servers don't have RJ-45 style KVM connectors, using CAT5 for KVM data means we need dongles. While using dongles allows me to the same KVM switch for old PS/2 and new USB servers by just picking the right dongle, I do have to shell out $85-150 apiece for them. Cheapskate that I am, I use old analog KVMs in the lab and insist on buying switches on eBay that use standard connectors so that I can buy cables for $10-30, where vendor specific cables can cost as much or more than dongles.
I gave up on the one console and single user KVM switch for each rack for my consulting clients a few years ago. Single access leads to server admins fighting over the one console that can access the servers in the rack, all rebooting because they overloaded the PDU circuit breaker. Not to mention lots of "excuse me" as I have to squeeze past the rack with the extended console, especially the execrable Dell ones (RU943) that pull out a yard from the rack before the screen flips up to eye level. For the past few years, I've been recommending multi-user KVMs so multiple admins can access servers on the 16 or 32 port switch at the same time.
Being tired of schlepping my tired old body down to the data center to address a server that won't come back from the reboot because it is just waiting for an F1 to clear the case has been opened message, I've also added IP access to the list of recommendations. Some of the early VNC-based IP KVM switches I used were truly abysmal, multiple mouse cursors, mouse cursors flying all over the screen like they had a mind of their own and support for just 256 colors all made the IP connection a less than pleasant experience.
Today's IP KVMs are somewhat better, but I wouldn't buy one without trying it out first. At $300/connected server, a full featured KVM isn't a trivial purchase. For that price, you can choose between rack mount switches and one port IP KVM dongles like the Lantronix Spider. But my next data center won't have conventional KVMs at all. Instead I'll have a monitor and touchpad keyboard like the Adesso SlimTouch Pro on a cart for initial server setup. Once I set the IP address for the server's out-of-band management card, which Dell calls a DRAC and HP an ILO, I'll use it to provide IP access to the console. Dell and IBM servers have VGA and USB ports on the front to make this easy, and the remote management console is usually about a $150 option that gives me as good a console experience as the IP KVM switch and lets me reset or power cycle a hung server to boot.