Long term storage of data on a hard drive?

How much danger is involved in leaving data on a hard drive and then storing that hard drive somewhere long term (e.g. 5-10 years)

Will the data degrade over time since the hard disk is not powered on?

Would an enterprise grade hard drive be better? Or an SSD?
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the only good storage solution is carving it in stone
Kent DyerIT Security Analyst SeniorCommented:
If you store data on one disk, this is not good in an enterprise for the following reasons:
1. If you have only one copy and the drive is lost or goes bad you have only one copy
2. If your office becomes a smoking crater, you need a copy offsite so that you can restore your office quickly
3. At the very least you will want  copy of the data on another drive.  That is why when we would use mirror drives.

There are many other reasons and above is a sampling to help you get started..


Lee W, MVPTechnology and Business Process AdvisorCommented:
Depends on the environment you store the drive in.  I've got drives that still work fine after 10 years, several years sitting idle (been "VHD'ing" them lately for archive purposes).  But then I've got drives that were dead out of the box.  And if you store them on the shelf by the docks, the humidity and temperatures could easily cause the electronics to corrode.  If you store them in an appropriately climate controlled room and you're likely be able to access them just fine.  BUT, keeping AT LEAST two copies is critical and ideally in two geographically dispersed locations.
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We do not use HDDs for long term storage. In our disaster recovery situation we use back LTO 4 tapes for indefinite data retention due to reliability, cost of disks and security. The debate between both methods rages but really depends on your situation.

The article below also discusses the debate.

since a rotating drive when stored for long periods can develop "cementing" between parts, which will stop the possibility to rotate, the drive should be powered up at least once a year
For long term storage, (more than 10 years) you also need  the sytem to read the drive, eg the IDE or sata interface, + system and software (drivers)  that can use it
example : who is able to read the first HDD's  still ? and the first floppies ?

good info on the history :  http://en.wikipedia.org/wiki/Hard_disk_drive
All magnetic media does slowly decay.  I'm not certain of the time frame but I believe that LTO tape is supposed to be a max of 15 to 30 years.  Hard drive platters are likely less than tapes.  I think that mechanical issues are a much larger problem and will be more likely cause a failure before magnetic decay.

Here's a pretty good short article that hits most of the issues with hard drive long term storage.  I think it is a few years old but still applies.


Data stored on a SSD will also degrade over time.  Typically you will see memory chips with a 10 year rating for storage applications (though much longer is possible).  When you write data to a flash chip the memory is electrically charged,  it is not a magnetic medium so its not subject to the same issues as tapes or hard drives for magnetic decay.  

Basically by checking the charge we read a 1 or a 0 in each bit.  So the typical 10 year spec means that after writing data the charge will potentially leak enough that after 10 years pass the charge will be too low and the written data will no longer be readable.  If the data is re written the 10 year decay will be reset.

The more the SSD is rewritten the shorter the decay time will become.  So you would not want to use a SSD that was run in a server a server for archiving anything long term.  Memory that was rewritten say 1,000 times will have a significantly reduced lifetime in terms of decay speed, by significant I mean it could cut the time in half.  Modern drives track usage of memory and manage wear as best as possible but for a archive application  you would want to get a new drive,  test it, write the data and put it on the shelf.  This also means don't overwrite it any more than needed.  (Same goes for tapes used for long term storage as well actually, ideally write a tape only once).

While mainstream flash SSD's are fairly new compared to mechanical hard drives,  flash memory has been around for quite a while and is very reliable.  It has just been too expensive (and too slow) for consumer hard drives until recent years.

The risk of a controller board failure is somewhat similar to the risk for a SSD failure from being stored - corrosion or failure of the circuit board.  The SSD is just a circuit board like a drive controller board.  So a SSD has only one major failure vs multiple potential problems with a mechanical drive.  Plus if you just drop a mechanical drive on the floor it could be trashed,  the SSD is a safer bet.

Though SSD's are much improved in performance and cost the price is still quite a bit higher for storing backups of any significant size as compared to tapes or mechanical hard drives.

If it fits your budget,  do your homework before buying any particular SSD.  Rewrite is not a issue but you want to check the lifetime of the flash memory.    10 years is a typical  specification but not all flash memory is the same and as memory get denser/cheaper the lifetime may get lower.  SSD drives in general have good memory chips,  I would more concerned with USB drives or SD cards memory chip quality.  Also the firmware/controller  on some drives have issues so avoid anything with alot of DOA type complaints.

Also I would not recommend going a full 10 years on the shelf,  5 should be no problem though.  After that start checking data and rewrite it if needed.  As with any backup having just one copy is dangerous,  you need at least two full copies.

'mirroring' is NOT a backup.  Anything written to a mirror array is automatically written (or deleted) from all mirrored drives at the same time, for better or worse.  So a corrupt file/virus etc will effectively hit all mirrors at once.
Scott CSenior Systems EnginerCommented:
When it comes to hard drives I don't expect the data to be there for more than 5 min.  Hard drives fail.

For long term storage you need to use a high-quality tape and keep it in the proper environment.

If your data is important you won't risk it.  Yes, tapes and tape drives are expensive; but how much money would be lost if your archived data was lost?
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