A Scary Tale of Loss and Tragedy
Imagine it is late one evening, a cold wind is howling outside your window and you have been chained to your computer, editing all day, feverishly working on customer images to meet a looming deadline. This might seem like the scary part of the story, but it’s not. You have worked on hundreds of images during the day and BAM! your drive fails. Insert scream of terror here, this is the scary part. If you are working on a single drive now the weeping, pounding on the table and wails of despair would begin. Eventually your tears would dry and you would be faced with the cold hard reality that you will need to restore the files from your backup. Which means those long hours spent working were for naught and those beautiful edits will have to be done all over again. So you revert into a catatonic state until morning where, like Bill Murray in groundhog day, you repeat the previous 24 hours.
But this doesn’t have to be a horror story. If you were working on a RAID array the drive could fail and you might not even notice it! Then you could calmly plug in a new drive and continue working while the arrayremirrors and you are once again protected from a drive failure.
The most common mistake I see photographers make in their image protection strategy is to use a RAID array for their archival storage and to use a single drive for their working files. This may seem counter-intuitive but the best use of RAID is for maintaining your working image files, not for your archival storage. Let me repeat, RAID is best used for your working files and regular storage is best for your long-term archive. Why? It is simple. RAID automatically updates all copies of your files on the drives every time you use them, so your changes are protected at all times.
Which RAID is right for me?
It seems there is more confusion about RAID technology than just about any technology we photographers are faced with. RAID, which stands for Redundant Array of Independent Disks, is geek speak for technology that maintains copies of your image files on more than one disk so that if a drive fails your images are not lost. That is it plain and simple.
The original RAID is called RAID 1 and is a two-drive array that makes a copy of every file onto both disks. This is commonly called mirroring, because the drives are mirror images. This is the simplest form of RAID but also the most costly, since you have to buy double the storage to support it.
RAID is the next most common form of RAID where data is striped across a greater number of drives, optimally 4 or more. This method is not mirror images but copies of the files are distributed across all of the drives so that if any 1 drive fails the array can be “rebuilt” by the remaining drives. Just stick in a new drive and in an hour (or a few) you have a protected array once again. A four drive array means that you will have 75% of the storage available for you to use instead of the 50% used by RAID 1.
Here is a sample calculation. Don’t worry the scary part is over, although math does give many of us the chills!
What about RAID 10 and other variants?
There are other variants of RAID, most notably RAID 10, that are emerging but these are generally best used for more specialized applications like relational databases and are likely overkill for the general photography studio.
Which type is right for me?
Backups Need Backups
I am guessing that more than a few of you are thinking, wince there is less than a 1% chance that both drives in a RAID 1 array would fail simultaneously, doesn’t this mean I don’t need to make backups anymore? Now I am getting scared! No there are so many things that can still go wrong that RAID doesn’t protect against like file corruption, catastrophic controller failure in addition to the very rare case where more than one drive fails at the same time. Please make regular backups and have an offsite strategy, but wait that is the topic of discussion for part 2 in this tale of loss and tragedy.
Written by Frank Myers