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Jumping the gun

Posted on 28 Jan 2009 at 16:12

Steve Cassidy finds that in times of recession there's no middle (sized) ground, and looks at a monster server out of a datacenter manager's dreams.

This way of handling drives is the closest you're likely to get to that oft-abused notion of Cloud computing, because the RAID card - if it's worth its salt - will isolate the drive letters you see (the logical drives) from the physically spinning disks and mechanisms inside the case. (I apologise to my technically savvy readers for this kindergarten approach, but I've found this is a concept that many well-clued up network owners suddenly click with as they read: and if the fate of the server I'm talking about has any lesson to teach us, it's that when "savvy" meets "na?ve" in the Forest of Buzzword, trouble is to be expected.)

So just what does this have to do with "clouds"? Well, it's a local embodiment of the Cloud concept - that is, that you can throw your data up into the Cloud, where the angels will look after it for you. You don't need to know anything much about all that hot, dirty, sinful hardware, because it's built to be so fault-tolerant that you can relax and treat these logical disks as if they really were where your data is stored. However, if you look more closely at the picture, you'll see that this is no more than a rash act of faith.

The Intel motherboard inside this server has a rich variety of connectors: there's even internal USB to enable that smart trick of booting from a flash drive, as well as a row of SATA connectors for setting up a more primitive version of a RAID set if you don't want to cough up for a smart RAID card. Having inspected my pictures, the eagle-eyed among you will have spotted something curious, namely that little red SATA cable that doesn't originate from the RAID card but instead from these motherboard SATA ports. An incurious buyer (and that certainly includes the client who bought this beast of a machine) might guess that this lead is for connecting a CD-ROM drive, and I'll confess that I spent a few hours convinced that was the situation while struggling with the box's extreme slothfulness.

Only once the top front cover was unscrewed was the nightmarish truth revealed, that this 15-drive monster actually boots up from... a single 2.5in SATA laptop drive! It took me about five attempts to actually verify this, eventually having to write down the model number from the sticker on the drive and triple-check the boot device order in the BIOS. Yes, indeed, the corporate CentOS installation on this 30kg monster groans into life from a tiddly 5,400rpm laptop disk, then in the usual Linux way mounts that humungous 7,200rpm 16-disk RAID array as a top-level folder within the overall filesystem.

Here, we're faced with one of the most sacred cows of the Linux religion, a belief that I've always thought highly debatable, that you can run the OS from a simple single drive, because recovery is trivial and needn't involve your data or the main RAID array. Save the RAID for your data, they say. As with so much else in Linuxland, when I analyse this notion I find a mixture of ancient anachronistic approaches ("we were dealing with this back in the seventies") with an impatient craving for bleeding-edge martyrdom ("this will all make so much sense once solid-state storage becomes the norm"). Well, yes it will, both of these statements are true as sound bites, but both are fictions - one a historical novel, the other sci-fi - and we're trying to fix things in the here and now.

Let's look at that assertion that non-spinning, solid-state drives will make this type of server architecture a much more sensible option in the near future. You can actually try it out right now, although not from the vendors of this particular server. There's a custom Linux distribution called unRAID (see http://lime-technology.com), which makes this notion into a present-day reality, assuming that your spare hardware and USB drives will agree to allow the former to boot from the latter. But here's the problem - I still don't buy into the whole idea.

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