“power Outage”-save / Like Embedded Systems

Home » CentOS » “power Outage”-save / Like Embedded Systems
CentOS 13 Comments

I would like to setup a small system based on CentOS6
“power outage”-save as possible. The hardware will be switch off by pulling the plug.

To accomplishing this goal, I would mounting some fs parts readonly (e.g. /usr) and thinking about tmpfs for volatile parts (e.g. lock, run under var). Additionally “optimize”
some vm.dirty_* kernel- and fs/ext4 parameters. /persistent would be used with jffs2 on a CF card. So far the theory.

Does anyone have some experience with such type of systems?
Any pointer to pitfalls are welcome.

13 thoughts on - “power Outage”-save / Like Embedded Systems

  • I would say almost the same: put it behind _APC_ UPS, and install apcupsd. As apcupsd will is designed to talk to APC made UPSes. It may talk nicely to other brands, but I myself do not take chances. And APC is the best in my experience. (Of course, there will be a couple of brands with hardware on the same level…)


    Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247

  • actually, I’d take an Eaton Powerware (formerly Best Power) over a APC
    any day.

    APC BackUPS grade stuff is strictly cheap consumer gear, I’ve had dozens of them fail over the years, all different BU models, the battery fails, you put a new battery in and the UPS still won’t work. They consistently overcharge the batteries so they die in 2-3 years, when they should last 5+.

    The APC SmartUPS stuff is significantly better, but also a lot more expensive.

  • Is there anything similar to apcupsd for that (preferably open source)? (I
    do remember ferrups… ;-)

    Indeed, I do stick to SmartUPS … I should have mentioned it. Thanks, John for weighing in !


    Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247

  • John R Pierce wrote:

    I think I may have an Eaton, or Compupower, at home. I think most of the consumer-grade ones are similar.

    The SmartUPS are… but then, overwhelmingly, mine are rackmount. I have mentioned here, before, though, that at least with the SmartUPS, you can easily, and far less expensively, buy replacement batteries, but they
    *MUST* be HR (high rate) batteries; anything else, and the SmartUPS don’t believe they’ve been replaced correctly.

    Isn’t even a price difference – it’s just for a different market, and most of the vendors, nor the OEM’s reps I’ve spoken to, know *anything* about this.


  • they have a whole GUI power management package that runs on linux but I
    tend to use the more basic shell-only stuff. most of the Eatons I’ve used have had ethernet, they have a web interface on the UPS to configure, you can list dozens of systems the UPS can lob status updates at, and use it with nut [Network UPS Tools, available from epel] or whatever… nut works with serial port and UPS based UPS’s too.

  • quality VRLA (SLA, AGM) batteries are capable of delivering massive current loads, I’ve not had any problems using these on good UPSs. At home, i’ve got an /ancient/ SmartUPS2000 (2KVA) tower unit that I
    repopulated with Panasonic 12V 20AH ‘motorcycle’ batteries. its been running great now for nearly 10 years, and STILL can keep my entire home computer load going for 4+ hours in a failure. These batteries are WAY past the ‘normal’ end of life, but are still doing very strong. I
    even put a safety light on them, a floor lamp with a 7W LED bulb bounced off the ceiling, thats left always-on, as this room is quite dark.

  • John R Pierce wrote:

    Right… at home. I’m running mostly SmartUPS 3000s, rack mount, that take eight batteries (which I can buy for about $100), or I could buy a new set, with sled, for way over $300…. The HRs should work in anything… but I’ve got some of the 3000’s that peak at over 90% usage (say, 3
    64-core servers running flat out with a load over 70), and these batteries allege, at that kind of load, < 15 min, maybe < 7. With the daily (or twice daily - wonderful line we have here at a huge, major US gov't agency in the DC 'burbs), it's fine, and they don't notice the second or two blips. mark

  • I was thinking more in line of what apcupsd does: it runs as a daemon, talks to UPS (and puts wall message about events like power loss…), and executes command to cleanly shut down the box if less than (whatever % of battery juice you configured to start clean shutdown at), and will issue command to cancel shutdown if power returned after shutdown started
    (sometimes you can do it…). And I usually don’t need to do any configuration (using GUI or command line utility) of the UPS itself… so after initial configuration of apcupsd I never get back to it. And, BTW, if you have half of a rack behind one UPS, you can set apcupsd on one machine to talk to UPS, and on other machines set apcupsd to talk to apcupsd on “master” machine making all of them aware, and act as necessary.


    Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247

  • Am 01.10.2014 um 00:53 schrieb John R Pierce :

    $ modinfo jffs2
    filename: /lib/modules/2.6.32-431.29.2.el6.x86_64/kernel/fs/jffs2/jffs2.ko license: GPL
    author: Red Hat, Inc. description: The Journalling Flash File System, v2
    srcversion: 8455E744807A823ED40A4E8
    depends: zlib_deflate vermagic: 2.6.32-431.29.2.el6.x86_64 SMP mod_unload modversions

    the consumption of resources like memory and storage is not an issue. The main reason to stay with C6 is our internal processes. Another distro to be maintained is not an option. I will check the implementation of the distros above … thanks.