To keep your data center serving its users, out-of-band management for servers has always been necessary, and up until a few years ago a KVM over IP switch was often a necessary evil.
High-density KVM over IP switches were the logical next step from crash carts. Being permanently cabled into servers’ keyboard, video and mouse ports, they became a central point for always-available, BIOS-level remote server control, saving the mad scramble into the data center floor to find & cable up an unresponsive server, thus saving downtime.
Unfortunately for the act of server management itself, KVM over IP switches had all the usability of QWOP. Being an external bolt-on without direct access to the system bus, even enterprise-grade solutions suffered from poor video quality, sluggish performance and mouse sync issues.
It has improved, with traditional KVM over IP being deprecated by a one-two punch from virtualization (where the hypervisor serves KVM with direct access to the virtual video and mouse drivers in the guest) and lights-out management cards (HP iLO, Dell iDRAC, IBM IMM, etc. – secondary computers embedded in the server with direct access to the system bus). Data center out-of-band server management vendors once heavily invested in KVM over IP have now relegated it to a bit player in their solutions.
Even in its virtual form, KVM over IP is still not an ideal out-of-band management technology for many of the same reasons that, generally speaking, CLI continues to trump GUI for remote administration.
The humble serial terminal server has evolved into today’s advanced console servers and data center infrastructure management appliances. Like the KVM over IP switch, it’s a concentrated management endpoint, but unlike the KVM over IP switch that can only see pixels, it can log and monitor all plaintext management traffic passing through it.
It can even automatically control the server in response to pre-defined patterns. Kernel panic on the console? Email the stack trace, then IPMI or PDU power cycle. New admin stopped a critical service? Terminate their session, start it back up.