yanfali ([info]yanfali) wrote,
@ 2009-01-03 22:46:00
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DVD-RAM on Linux
My friend Craig has been extolling the virtues of DVD-RAM for years now, but not having a drive that supported it I just considered it another proprietary DVD format that would disappear up it's own behind. It turns out, I now have at least 2 DVD-RAM compatible drives in my possession. So the other day I picked up a 5 pack of disks (about 7USD) and today I gave it a spin.

I inserted the disc into the drive and expected to be greeted by k3b. Confused at it not starting automagically I started it manually. Show Media Info. Hmmm, no media detected. I start googling around. I get hints that you just format it and use it like a disk. With zero expectations I attempt mke2fs -j /dev/sr0. It starts formatting the drive! Holy crap. It's like a 4GiB floppy! I think I have a use for those.

According to wikipedia, DVD-RAM discs can be written to 100K times. Compared to say DVD+RW which tops out at around 1000 times. And apparently the manufacturers think they'll last 20 years. Will I have anything that will be able to read them in 20 years... that's a very good question.

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[info]slothman
2009-01-04 08:19 am UTC (link)
My plan is “whenever online storage gets big enough to hold an entire collection in lossless format, get an internal repository for active use and an external one for backup and rip everything”. Then migrate to the next bigger format when a new online storage medium comes out, and just make sure that I can always read the data formats even if the storage medium is progressively going out of style. Terabyte-range drives are getting cheap enough that it’s getting close to time to re-rip all ~700 music CDs to lossless format instead of MP3; the next batch to do will be the DVDs...

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[info]yanfali
2009-01-04 05:43 pm UTC (link)
Agreed. It's sort of been my data plan all along too. Though I'm very bad at backing stuff up. The problem with large disks though is greater chance of failure. I've been considering looking at ZFS on Nexenta because of the advantages of end-to-end checksumming. No Linux file system has that kind of support yet. I keep holding out for a next gen linux file system based on the same principles of WAFL, like BTRFS. However, it looks like that's not going to finished until 2010.

If I sit on my hands long enough, then it's possible 1TiB SSD drives drives will become affordable enough for backup use. For example, I saw a Transcend 64GiB USB flash drive for less than 80USD. For a 1TiB drive we're talking 1280USD at current flash prices. Assume a year-on-year decline, plus process improvements, technology advances - think memristors, and we're talking about 320USD within 2-4 years for that size of drive. Now it likely won't be fast, but I'll trade that for no moving parts; ok, you might have to worry about failing components due to RoHS. If one doesn't write to it very often, like for backups, then it'll be just fine for about 10 years or possibly indefinitely.

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[info]slothman
2009-01-04 07:57 pm UTC (link)
I figure it’s a matter of having one backup drive and one online drive, and it’s fairly unlikely that you lose both at once. Ideally, I’d like to have my backup drive be a RAID-1.

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[info]yanfali
2009-01-05 12:29 am UTC (link)
Good idea. Ironically the statistical chance of a disk failure in RAID1 actually increases with the number of drives you have. It's just less catastrophic.

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[info]slothman
2009-01-05 12:37 am UTC (link)
The statistic that matters is how likely it is that you recover your data. :-)

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[info]yanfali
2009-01-05 12:51 am UTC (link)
My only conclusion so far, to maximize data retention and recovery, is make many copies and distribute them as widely as possible. Amazon S3 is starting to look really good.

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[info]slothman
2009-01-05 03:43 pm UTC (link)
Hmmm... need a file manager program that puts nothing but encrypted files on the remote site but makes the archive look transparent to the user...

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[info]yanfali
2009-01-07 04:39 am UTC (link)
How hard could that be :) some QT magic, sqlite and a little openssl/pgp and you could be in business :)

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