I recently upgraded one of my storage drives from 2 to 3 TB, and wanted to report some of what I found. Upgrading drives beyond 2.2TB can lead to some complications, including either hardware or OS compatibility. I found that most of my firewire drive enclosures don’t support the larger drives, and none of my USB enclosures do. All of the eSATA configurations handled it with no problem. (Tested on Mac only).
We’ve run into a limit like this before. Many years ago, IDE connections would only support volumes up to 137 GB in size (shown as 128 GB in older Mac OS). If you connected a drive that was larger, you had to format the drive into partitions if you wanted to take advantage of the drive’s full capacity. ATA-6, which was introduced in 2002 lifted that limit to an astronomical 144 petabytes.
Serial ATA (SATA) shares the ability to support very large volumes, but the hard drive controller or bridge board (the thing that lets the hard drive talk to your computer’s logic board) may be limited to 2.2TB. Since Operating Systems like Windows XP don’t support volumes larger than 2.2 TB, manufacturers limited the capacity of the controller to make such large volumes. Windows Vista and 7 don’t have the limitation, as long as the drive is formatted as GUID. Mac OS 10.4 and later also don’t have that problem.
So what happens if you put a drive in an enclosure that does not support the volume size? First, you’ll be asked to format the drive, since it won’t be readable to the computer. This can cause a heart attack if you have a bunch of data on the drive and don’t want to reformat it.
Testing my Hardware
I took this opportunity to test some o fmy hardware to see which devices supported 3TB drives. Here’s what I found.
SATA – All of my SATA connections supported the large drive. This included the internal connections on my Mac Pro tower, as well as the add-on eSATA cards I’m using (one for the desktop and one for the laptop). Note that most of these cards have upgradable firmware, and you might need to do that to allow the large drives, if you have an older eSATA card. I upgraded the firmware of my cards to be compatible with 10.6 a while ago, so I’m already running the latest firmware.
Firewire – I have quite a variety of firewire enclosures in use, and nearly all of them don’t support the large drives. Note that many of these are 4-6 years old, so it’s not particularly surprising that they were designed to top out at 2.2 TB.
The Wiebetech (CRU Dataport) devices that I have did not originally support the large drives, but have upgradable firmware that solved the problem. This is one reason that you pay a bit more for Wiebetech, but you get some real value for your money.
The cheaper Cooldrives enclosures that I have don’t support a firmware upgrade. I’m looking at replacing the Bridgeboards in these units with something like this. It has a current Oxford 934 Firewire controller, and should be easy to swap into my multi-bay enclosures.
The older OWC enclosure I had was not upgradable, but the current ones seem to support large drives. One great thing about OWC is that you can get a smart person on the phone to answer these kinds of questions easily.
USB - None of the USB devices I own seem to support the large drives. That’s not particularly surprising, since most of my USB enclosures are older.
Drobo – Did not test, but the company website shows support for 3TB drives. I’d make sure my firmware was up to date before installing one of these.
The Bottom Line
Because of the configuration of my system, and my data needs, I eventually decided not to use the 3TB drive for archive data storage. My photo archive lives in older firewire enclosures that it connected to an iMac server, and none of these devices currently support 3TB. I decided to let these drives remain as 2TB for a while, since I have plenty of space left on them.
I have put the 3TB drives into service as Working File backups that protect the current files on my Mac Pro tower. I’ll use these as swapper drives that let me take current work off-site. Since my works-in-progress data is edging toward 2 TB, the extra capacity will be useful here right away, since I can allow Chronosync to save additional copies of changed and deleted files. These drives connect by eSATA, so there is not problem with the large volumes.