Apr 222012

Lately we’ve been hearing about more people using mirrored drives as part of their backup strategy.  If you already have it in place, don’t get rid of it; but, it is not something that we particularly recommend.  Let’s take a look.

Mirrored drives come in two flavors:

  • two drives on one controller (Figure A); or
  • two drives, each on their own controller (Figure B)two drives on one controller

As the name implies, each time you write to one disk, the identical thing is written to the other disk.  If one drive goes bad, the theory is that the other drive has your data and you have no downtime, except to replace the failed drive at your convenience.

Sounds great. In theory.  The reality is that if one drive is fried with a power surge, they both are.  If the controller goes bad, you might have two drives that still have your data, but you are still down until the controller can be replaced.  If the controller goes bad in such a way that it ruins one drive, the chances of the other drive escaping damage are pretty slim.

two drives on two controllersIf you have each drive on its own controller, you are in a better situation; again, in theory.  However, you are still in a position of having all the hardware fried with the right power surge and in the same sad position as anyone else with fried hardware.

Frankly, we recommend you spend your money in other ways.   Online (cloud) backup and an external hard drive for backup are two excellent ways to spend that money and give you a much better chance at recovery in case of failure.

Right now, Amazon offers free online storage of ALL your music (whether it was purchased at Amazon or elsewhere) if you purchase a storage plan.  The plans start at $20/year for 20GB.  Other cloud services include DropBox or SugarSync.  If you have a little more money to spend, services like Carbonite make a good choice and back up your drives automatically.  (Our professional services can help you configure your online backups beyond the “standard”, which may not be backing up all your data.)

You can buy a 32GB SanDisk Cruzer flash drive (thumb drive) for less than $20. (Price fluctuates. Great for backing up your daily work product.)

Whatever you select for your backup strategy, remember: pick at least two (preferably three.)

You can never be too thin, too rich, or have too many backups.


Note: a mirrored drive is not to be confused with a RAID array.  A drive array is an arrangement where 3-5 drives are configured such that a portion of your data is written to each drive, and is most often found on file servers.

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