Ed Wilts wrote:
FT is rarely required. FT *hardware* has been out for many years but is rarely purchased. It's very complex and expensive.
Rant on.
I've been involved in deployment of some of the listed FT hardware. It went in at a software vendor's recommendation, and for no other reason.
The result was a single server that took 12RU of rack space, cost more than a half-stocked Bladecenter, and, most importantly, fell over every time you breathed on it. "Oh, you applied Windows Updates? We don't support that, it's no wonder your server no BSOD's regularly", and, "oh that bad driver of ours is present on both sides of the hardware mirror" were common statements, from a support team that could only get replacement hardware parts through international shipping.
I had an HP DL380 which, as confirmed by our monitoring software, went down less often and for less time.
I can't express enough what garbage these solutions are. Get two servers, use HA, I can guarantee the end result will be more uptime.