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Facebook Experimenting With Blu-ray As a Storage Medium 193

s122604 links to CNN's explanation of what may be the future of cold (or at least lukewarm) storage at Facebook, which is experimenting with massive arrays of Blu-Ray discs for seldom-accessed user files. Says the report: The discs are held in groups of 12 in locked cartridges and are extracted by a robotic arm whenever they're needed. One rack contains 10,000 discs, and is capable of storing a petabyte of data, or one million gigabytes. Blu-ray discs offer a number of advantages versus hard drives. For one thing, the discs are more resilient: they're water- and dust-resistant, and better able to withstand temperature swings. Their data can be restored more quickly, and they're easier to transport. Most important, though, is cost. Because the Blu-ray system doesn't need to be powered when the discs aren't in use, it uses 80% less power than the hard-drive arrangement, cutting overall costs in half.
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Facebook Experimenting With Blu-ray As a Storage Medium

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  • by tomhath ( 637240 ) on Saturday August 23, 2014 @05:29PM (#47738431)
    Can I ask Facebook to delete my stuff from one of those (assuming I had a Facebook account in the first place)
  • by evilviper ( 135110 ) on Saturday August 23, 2014 @06:47PM (#47738919) Journal

    Enterprises have been doing this with tape for 30 years.

    Tape has always had a limited life-span and is too easily damaged to completely trust with high-value archival data. Instead, archival on tape usually means "we're not quite confident enough to just delete this crap".

    Meanwhile, Sony's enterprise-grade write-once (WORM) magneto-optical (MO) discs have been around for decades, are physically tougher, and impervious to magnetic fields, sold with 100-year warranties that even cover data-loss recovery costs.

    BD-RW can certainly be seen as Sony's MO technology being brought down dramatically in price due to economies of scale, and intentionally to allow them to compete in the consumer space.

  • by lucm ( 889690 ) on Saturday August 23, 2014 @08:03PM (#47739335)

    What you describe is called a MAID and over the years it has proven quite unreliable. Hard disks are sensitive creatures and don't age well when being powered-on/powered-off randomly, and because of the nature of cold storage it is difficult to achieve a right balance of redundancy and power savings.

    Also I would advise you to be careful when you label something as "phenomenally stupid" otherwise in instances like this one it may make you look like you are "phenomenally uninformed".

  • by Eric Green ( 627 ) on Sunday August 24, 2014 @12:50AM (#47740445) Homepage

    You're actually talking about MAID (Massive Array of Idle Disks), a technology that I first encountered in 2002. Now-bankrupt Copan Systems was the company I first encountered that was doing MAID, and New SGI (i.e. former Rackable Systems) bought their assets out of bankruptcy in 2010. Most storage companies now offer MAID add-ons for their storage arrays, though not all of them allow completely powering down the drive like Copan's solution did.

    The upsides of MAID: Disks are cheap. Turning on and spinning up a hard drive to pull up some bits is faster than a robot fetching a Blu-Ray disk, placing it into a drive in the jukebox, and waiting for the disk to spin up and come online. You could store many more bytes in a cabinet with MAID than you could in an optical disk cabinet.

    Downsides: The disk drives in a MAID array simply don't last that long, comparatively speaking. Spinning them up and down all the time is hard on a drive. So you end up having to replicate data and from time to time migrate data to new drives as old drives reach their service life. The service life of rarely used Blu-Ray media that has always been handled robotically (i.e., nothing touching its surfaces ever) is such that Blu-Ray media from ten years ago is probably still usable, the technology itself will become obsolete like DVD-RAM long before the media wears out. Not so much with hard drives, though disk arrays basically have unlimited life given typical failure patterns (i.e., if you're using RAID6, a drive develops errors, you remove the failing drive from the array, rebuild the array on a new drive, and chances of having two more drives fail during rebuild and thus losing the array are slim for a 12-drive array). So MAID has not really taken off the way we expected ten years ago.

    At the time I first encountered MAID I was working for a company called DISC Storage, which had a NAS head which would automatically migrate little-used data to an optical jukebox in a way similar to what Facebook appears to be attempting. I designed and implemented the clustering function that would replicate the data between two NAS heads / optical jukeboxes, since the DVD-RAM platters were not themselves RAID'ed, as well as implemented a lot of the back end functionality for jukebox control and so forth. In any event, it looked like a NAS head but most of the files had been migrated to the DVD-RAM platters, and if you accessed one of those files, you would (at some point maybe 15 seconds later) get your data back as the file got read back onto the hard drive. It worked. But it was somewhat slow and cumbersome, because you're relying on a robot to go out and fetch the disk and put it in a drive, and disk robots then, and now, simply aren't that fast compared to media that's already in a drive ready to be spun up and read.

    So anyhow, it was fairly obvious to me by mid 2003 that optical jukeboxes simply weren't going to be the future. In the ten years since DISC went under (there is a German company by that name now but it isn't the same company, it bought the name and some of the IP), I have not had any inclination to work for a company doing optical storage, because it's clear that for most problems it isn't the solution. It's too slow, too bulky, and magnetic disk drives and magnetic tape drives just continue getting bigger and cheaper every day. And now, with SSD coming on strong, optical jukeboxes look even less compelling.

    So color me amazed. Optical jukebox and optical media technology essentially has barely moved on in the past ten years and what wasn't particularly compelling then, is even less compelling now. If you have need to keep data for a *long* time, this is how you do it... but frankly, I will be surprised if Facebook even exists ten years from now given the pace of innovation in the industry (though I'm just as surprised that Slashdot still exists!), so I question why they would do this rather than invest in LTO tape libraries, which have the advantage of being significantly denser.

"An open mind has but one disadvantage: it collects dirt." -- a saying at RPI