RAID battery issue with XServe

Discussion in 'Mac OS X Server, Xserve, and Networking' started by Pegasi Delta, Jan 20, 2012.

  1. Pegasi Delta macrumors newbie

    Apr 17, 2009
    I'm working as an IT and Media technician at a secondary school in the UK and have been tenuously taking care of the Mac network side of things. We have an XServe and about 10 client machines so it's hardly a huge setup, but I had literally zero networking experience (Mac or otherwise) before I started here a couple of months ago, and have basically been given reasonable responsibility over this side of things as I'm a Mac enthusiast in general. So basically, please bear with me if I ask some pretty basic questions.

    Anyway, the RAID battery in our Xserve (3,1 model, 2.26GHz quad xeon) has died and our IT consultant, who I've been liaising with on this issue, has had trouble tracking down the proper replacement part. At around the same time as the alerts in RAID utility started appearing, the Mac suite which is used for media studies, mostly editing in iMovie and FCE, started slowing right down. When we have more than 2 students trying to edit at the same time, their projects become stuttery and difficult to work with. The stuttering etc. isn't saved in the file so it's not affecting their final projects, just making the actual working process a lot more difficult for them.

    I guessed that this was due to write-caching being disabled automatically when the battery is conditioning (or when it fails in our case), which slows down write performance. Is this correct?

    If so, we've been looking in to replacing the RAID battery but have, as I said, encountered difficulty in sourcing the right part. Our IT consultant suggested that we might want to just install a compatible UPS, force write-caching on again and negate the need for the RAID battery altogether.

    As for my questions: Does anyone A) know of a good place to source the correct RAID battery replacement (again, based in the UK)? Or B) know of a reasonably priced and appropriate UPS that will do the job instead? And C) given the choice, which option would people say is better? I'd be inclined to go with the RAID battery itself since it offers 72 hours of power rather than the UPS options which only seem to offer a few hours at most, at least in our price range, though tbh I've no idea how necessary this length of backup power is.

    Any help would be much appreciated.
  2. belvdr macrumors 603

    Aug 15, 2005
    You are correct that the battery failing will cause write caching to become disabled.

    I strongly suggest you don't use a UPS as a replacement for the array controller battery. You should have a UPS anyway to ensure the system gets proper voltage during normal use and can cleanly shutdown in case of a power outage.

    The UPS will not be able to do the job the array controller battery was meant to do. Normally, an array controller's battery will keep the data in cache for 48-96 hours. To get a UPS to keep one server online for that time would require a small room of batteries (i.e. not affordable). I've seen it a couple of times where customers used a UPS like this and never monitored it. The UPS battery would fail for whatever reason, the power went out, and they lost data. It's a temporary band-aid at best.

    At this point, I would see if there's another reseller around or call Apple directly.
  3. Pegasi Delta thread starter macrumors newbie

    Apr 17, 2009
    This was my concern when our IT consultant suggested it as a solution. The battery is quoted as giving 72 hours backup, which is highly preferable to the 5 or so hours max that I could find in UPSs (most of them were around 2 in our price range...). Like I said, I wasn't sure if I was just being paranoid or not, it's good to hear that my logic wasn't way off. I'd hate to leave on a Friday afternoon only to have the power fail and the UPS only keep it going for a couple of hours, coming back after the weekend to find the kind of mess that makes me hate Mondays.

    Yeah I think I'll get in contact with Apple this weekend and see what we can do about a replacement. I'll suggest that we invest in a UPS anyway just to keep things safe, though I'm not sure how that'll go down on the budget end of things, that old favourite of a battle. As for that, do I need to know anything specific to our model of Xserve when buying a UPS? I'm basically unfamiliar with this side of the technology and don't want to buy something unsuitable for our needs.

    Thanks for your help and advice, it's good to know I'm not totally mad in thinking that a new battery is the best way forward. If anyone has any specific experience with sourcing this part/knows of a good reseller to try then I'd very much appreciate any help.

    Thanks again,
  4. belvdr macrumors 603

    Aug 15, 2005
    I use APCC and have for years. Everyone has their vendor preference.

    Just make sure the UPS unit you get works with the version of Mac OS on your system. Personally, I would get a model where you can replace the battery (unlike my home model) and connects over USB. You want to be able to configure the UPS to tell the system to shutdown if it has lost utility power and has less than 10 minutes remaining on battery, for example.
  5. Dominic49 macrumors newbie

    Jan 15, 2012
    p.s. I just bought 2 apple raid card batterys from apple directly for $35 a piece :D

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