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Do you guys know how much time needs to pass until the data stored on a hard drive starts to degrade? To keep the data intact for long periods of time, I heard you need to periodically rewrite it on the hard drive, like every 5 years or so. Is it true?
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hard drives fail and are not good long term storage devices. but you do not need to rewrite anything on them... if you want to keep data over long periods of time, get a tape recorder (computer tape recorders are used by large companies for their data) | |||||
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The conventional wisdom is that you should revisit your data every five years to make sure that you can still read it. The general consensus is that the magnetic platters in the drive will start to degrade in 5 years of storage. The bigger issue is that storage technology changes. That means a format that works today will be unreadable 5-10 years from now. The best option you really have is to have multiple copies on multiple formats and to check on the data at least once or twice a decade. That's really the only way to make sure that the data is both intact and on a format that can still be read. If you can afford it, you could always pay someone else to manage it. Services like Carbonite can store lots of data for long periods of time. They also can provide disaster recovery services in case your loose your computer and local backups. Hope this helps | |||||||||||||
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I bought a very old Zenith 386 system with an RLL full-height hard drive, circa 1987 at a local thrift store for $5. Had 640MB of RAM and a 386 CPU. Before you had IDE hard drives, you had MFM and RLL drives; these did not have the controller electronics on board but had ribbon cables that went to an ISA controller card. Very old drive. Plugged it up, got it to boot (after figuring out the "BIOS drive type" - it was something like 70MB) just fine. Had MS-DOS 5.0 installed. Scandisk revealed 1 bad sector on the drive. Might have been caused due to movement, this is from the era where drives didn't lie about their bad sectors (and had a "defect table" sticker on it). So I imagine if they are in climate controlled conditions and not subject to shock or vibration that they would last quite a long time. | |||
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It depends entirely on the ambient electromagnetic noise, the density of the media, and the quality of the read/write head. More noise, more dense data, and lower quality read/write mechanisms will result in so-called "bit rot" setting in faster. It's also going to vary depending on the quality of the internal motor and bearings. Part of the problem of spinning up an old disk is the fact that they're mechanical, and mechanical things don't age well without maintenance. On mag tape, I've always heard the limiting factor is the method they use to bind the magnetic particles to the tape backing. The shelf life in perfect conditions (no light, nitrogen environment, temperature controlled) for that is supposed to be about 25 years (which is a problem for hospitals, who are supposed to maintain data backups for the life of the patient). Tape continues to be used because it is cheap and very high density, not because it has a superior shelf life. Recordable optical media lifetime is about 100 years in theory (note that the discs haven't been around that long to actually test!) assuming absolutely no light after burning. Once you introduce an environment with light to recordable media, however, the lifespan drops drastically. 10 years at the most is what I've been told. True pressed discs last indefinitely as long as the media is internal to the disc medium, but those are extremely difficult to produce and are not economical for one-off disc production. This is what I remember from talking with a salesperson from Iron Mountain several years ago. We did not talk about magnetic disks, but I know they are not more reliable. Hard drives combine three elements: one magnetic, one mechanical, and one electrical. Any and all of these are prone to failure, and this is why hard drives are one of the most common devices to fail in an operational system. You'll also note that the most modern filesystems such as btrfs and ZFS do online "disk scrubbing" where the system will actively read and rewrite disk sectors to maintain the magnetic integrity of the disk. I would say 10-15 years of life if the density is not ludicrously high and you sit the disk on a shelf and don't touch it. | |||
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This will differ based on the type of HDD. 5 years sounds like a reasonable average, though. For archival purposes, magnetic storage just isn't the best option. You need physical storage, such as optical disks. These have their own types of kryptonite, but are generally more suitable for archival storage than magnetic hard disks. | |||
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