On Tue, 8 Jul 2008, Gerhard Fiedler wrote:
> Depending on the amount of data and the physical abuse the media must be
> able to take, I find (multiple external) harddisks quite useful. While they
> eventually die, they seem to do so rather arbitrarily, so the chances are
> good that when one dies, the other copy (copies) are still alive.

This is only true if the drives are of different ages and companies.

A batch of drives will often start failing one after another, often with 
less than a day between failures.  I have seen this with my own eyes many 
times.  A common disk setup for high end storage is raid 5, where one out 
of a group of drives can fail with no loss of data, but two failures at 
the same time will fail.  Having a second drive fail before you can get to 
the rack and replace the first bad drive fail is common enough that a new 
raid level was introduced where two drives can fail and it keeps running.

And that is just the most common.  Many systems have redundancy so dozens 
of drives can die and the system won't even slow down, let alone loose 
data.  But that is for setups were you might have a thousand drives all 
running in a massive array.

For my own personal use, I have two backup drives.  Every night an 
incremental backup is made to a drive, alternating each night.  When a 
drive is full, I buy another and put the old one into storage.

There really isn't any better way for 100's of gigabytes of storage.  tape 
backups are just too small or too expensive or both.  DVD have high rates 
of failure and only store at most 8gb a disk.  Flash memory is too 
expensive.  Anything else is just not dense enough.

But there are alternatives.  There are internet based sites made for 
storing large amounts of data.  Just use several at once so if one goes 
away you still have your stuff.

www.adrive.com for instance gives 50GB of storage for free.

--
Ian Smith
www.ian.org
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