Spending Your Money Wisely on Digital Image Storage
[by Richard Anderson]
With every New Year, digital photographers, (which is pretty much all of us now), face decisions about how to make room for a new years worth of image files.
Most of us have been shooting digitally long enough to know approximately how many gigabytes we create in a year’s time. It has inched up as we traded up to higher megapixel cameras of course, but the good news is that hard drives have become larger and cheaper. So what is the least painful way to accommodate these growing collections?
There has always been a lot of buzz about RAID enclosures, but I would propose that buying the largest available drives and arranging them in JBOD enclosures is the easiest, cheapest, safest, and most workflow friendly arrangement for digital image storage.
I’ll make my case:
• Easiest—Each drive needs to be backed up. Take a 2 TB drive and fill it to approximately 75% capacity. Now do the same with a second 2 TB drive. Now your hard drive storage is properly backed up. Easy!
Take the backup drive offsite for maximum protection. If that isn’t an option, keep the backup drive disconnected and only connect it when you need to synchronize with the primary drive.
• Cheapest—In a JBOD setup- you get full value of the drive cost because you get to use the whole drive for storage. With any RAID other than RAID 0, you lose some portion of the drive space to redundancy. With RAID 5, you will lose the entire capacity of one of those 2 TB drives. On an energy saving note, RAID arrays keep all the drives running when they are on. A JBOD enclosure can have drives on or off independently of each other.
• Safest— If RAID 5 didn’t have to be backed up, you’d come out ahead moneywise, but unfortunately RAID 5 doesn’t protect you from data loss due to equipment failure, file corruption, Fire, theft, or other disasters, so you will still need to back up all the data on the RAID, the same as you would for JBOD. I have discovered that many people don’t back up their RAID 5 setups because they focus on the word “redundant” and figure they’ll take the risk. Since JBOD is cheaper, there is less temptation to “cheap out” and not make your setup truly redundant.
An important fact that impacts safety is that in a RAID 5 setup, when one disk fails, there is a high chance that a second one will fail. The theory behind the error correction in RAID assumes that failures of drives are independent. It is often the case that the drives making up the RAID are the same ages. Since all drives are on when the RAID is on, this means that they all have the same number of hours of use. This means that the chances of failure of all the drives in a RAID are statistically correlated. Occasionally, manufacturers have a run of bad drives. Think about what happens if the RAID is made up of these drives.
• Workflow friendly—RAIDs are great until you run out of space. At that point, you will need to offload ALL of the data on the RAID, rebuild it with larger drives (or get a bigger box), and then restore ALL of the data back. It can take 6 to 8 hours to migrate each 2TB of data using a validated transfer utility. If you skip the verification, you will save some time, but you can never be sure that every “bit” of your data has transferred and is uncorrupted. With JBOD, you can migrate your data to larger drives on a less hectic schedule because you only have to do it one drive at a time.
Data Robotics DROBO enclosures relieve some of the pain of scaling up your storage capacity because you can mix and match different drive sizes. DROBO enclosures still consume more drive space than JBOD however, and the data contained on a DROBO still needs to be backed up.
My advice is to stay away from the fancy boxes. Get a sturdy multi-bay drive enclosure and a double set of 2 TB drives. It’s Easier, cheaper, safer, and more workflow friendly IMHO.
For more information on hard drive storage go here.