Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!rice!sun-spots-request From: paul%ppgbms@uunet.uu.net (Paul Evan Matz) Newsgroups: comp.sys.sun Subject: Re: UPS (power-backup) boxes for Sun servers ?? Keywords: Hardware Message-ID: <10057@brazos.Rice.edu> Date: 18 Jul 90 00:27:29 GMT Sender: root@rice.edu Organization: Sun-Spots Lines: 65 Approved: Sun-Spots@rice.edu X-Refs: Original: v9n258 X-Sun-Spots-Digest: Volume 9, Issue 272, message 1 In article <9852@brazos.Rice.edu> eho@clarity.princeton.edu (Eric Ho) writes: > >Has anyone out there been using those UPS (Uninterruptible power system) >boxes for Sun servers ? In particular, I want to get opinions about the >UPS boxes from Elgar (in San Diego)... So far, the only UPS we've found that will work well with SunOS is the IPS 400 + 600 from Elgar (800-854-2213). You can buy "Unisafe" for SunOS ($99) which is a set of sh scripts that monitor the state of the UPS via a serial port, and shutdown the Sun in the case of a power failure. The price of the UPS; something like $500-600. One unique feature that the Elgar has is the ability to shutoff its UPS output power to the Sun once it has halted. This is very handy when the power failures are frequent or long. (The key here is that the UPS has a built-in delay circuit which waits for 20 seconds after being signaled before it shuts off its output power; The Sun signals, then halts. This gives it 20 seconds to halt and flush. Without this feature, it is difficult to make sure the disk is flushed while under software control. Once the Sun has halted, it can't signal the UPS to shutoff. Your basic catch-22). Powering a monitor is problematic for most UPS, this one included. The problem is not power usage, by peak current. A 16" color monitor might use as much as 3 Amps peak (although only about 100 Watts average); That coupled with the Sun will amount to more then the max. for most UPSs (3.3amps max). Therefore, don't plan on powering you monitor. This will usually not be a problem for servers. Power just a SPARCStation 1 w/ 2 104M disks, the projected power backup time is something like 1.5 hours. I ran it for about 20 minutes without any noticable battery discharge (as shown by a battery capacity bar graph display on the UPS's front panel). The UPS monitor daemon process senses when power goes down by being blocked on a read of the tty; The UPS asserts CD when power goes down, thereby unblocking the daemon, who proceeds to start a countdown. (There's no connection to the Receive data pin). There are various configurable parameters that define how long the daemon ignores a power outage, how long it waits after it notifies users to logout and before it starts to kill off processes, etc. The daemon is built out of scripts, so it is easy to checkout and modify if you need to, although I think they could use a little more work. When it is finally time to shut off the UPS, the script signals the UPS by writing a file of all zeros out to the tty (the Transit Data pin is connected to the UPS). Then, unless the AC power comes back on, the UPS shuts off power to the Sun in 20 seconds. The script hammers as many processes as it can (including itself, by the way), sleeps for 20 seconds and then reboots (so if the power does come back on, the machine won't be sitting there halted). There is a race condition where, depending on the spacing of multiple power outages, you can get your power shut off during a reboot. (This is one of the things that need to be fixed in that daemon script). Another problem with the Elgar software is its installation instructions. On a SPARCstation, there are a few details which are omitted, like setting carrier-detect-ignore to false, and adding the serial port to gettytab. I think they are working on fixing this, though. I have no real info on reliability. So far, so good. The support from Elgar (Tod Fox) is very good. Hope this is of interest.