----- Original Message -----
From: "Per Jessen"
Don't forget that with a bigger/more expensive UPS, most of the time you have the advantage of hot-swappable battery's and/or a bypass function plus the ability to shut down more than one server if things go wrong. Most of the small UPS's have to be shut-down to swap the battery's. Furthermore with the big UPS's the battery voltage is higher resulting in low amp's on the battery's resulting in longer lifetime.
Erland, I think you're talking very large UPS'es here - I haven't seen anything less than 25kVA with hot-swappable batteries. Bypass mode yes, but hot-swappable batteries is another level.
---- I hot-swap batteries in 1 to 3 kva apc's all the time. It's not always a one-step tray-in-socket like a hot-swap harddrive tray, but, a common 2200kva 2u or 3u rackmount apc has a door that opens on the front and you can disconnect the plug inside, pull the batts out and put new ones in and reconnect the plug, all while on-line. If your unit has the connector on the back for extra external batts for more run-time, then you don't even ever lose protection. The power could go out while you are changing the internal batts and it would run on the externals. And of course the externals can be changed any time since they are just connected by a cable & a special plug anyways. Really any ups batts can be changed while on-line, as long as you can physically get to the battery. The small ones make this a little dicey just because you don't want to be having to move the ups around to tip it on it's side or turn it upside down whil all the cords to the production servers are plugged i the back because of the risk of pulling a plug out. It would be better, but not strictly necessary, to schedule a graceful shutdown than to risk losing power during the 20 seconds while you have the battery unplugged or risk pulling a server power plug while moving a cheap small ups upside down. To me hot-swap means "swap while hot", not "is convenient to swap". The more important factor is that better ups's constantly condition the power and are always on-line, where the cheap ones directly connect you to the dirty wall power as long as there is wall power. -- Brian K. White brian@aljex.com http://www.myspace.com/KEYofR +++++[>+++[>+++++>+++++++<<-]<-]>>+.>.+++++.+++++++.-.[>+<---]>++. filePro BBx Linux SCO FreeBSD #callahans Satriani Filk! -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org