We've been following the Drobo for the past couple of months, and if any one thing is clear, it's that Data Robotics has a lot of work ahead of it when it comes to educating the average RAID-ready consumer why they should lay down five bills for an external enclosure that comes with no drives. We know, it's a tall proposition -- but the Drobo isn't your average external drive array enclosure. To better illustrate why, let's quickly compare some common usage aspects between the Drobo, with its virtualized storage system, and what many (ourselves included) have in their home, a RAID 5 array.
(For simplicity's sake, this example could be any RAID 5 array, we're not gonna get too specific. RAID 5 is possibly the closest consumer analogue to the Drobo's virtualized storage, so we're not gonna talk about RAID 10, or 0+1 or anything.)
RAID 5 - Three or more same drives required. (Some arrays will accept dissimilar drives, but will function as lowest common denominator. So two 300GB drives and one 20GB drive will yield a 40GB array.)
Drobo - One to four drives supported; two drives necessary for redundancy
RAID 5 - Drives in caddies or typically somehow screwed/fastened into the enclosure. From here you may have numerous means of access, including eSATA, USB 2.0, FireWire, even NAS.
Drobo - Drives slide into and are secured by enclosure with no tools. USB 2.0 only, sorry.
Redundancy method and data awareness
RAID 5 - Block-level striping with spanning parity. Array is block-level unaware of data though, meaning nothing intelligent is done with free space.
Drobo - Virtual storage pool is redundant, but also block-level aware, meaning that it recognizes free space, and automatically uses it for multiple invisible backups should drive sectors become corrupt. (The added benefit of block-level data awareness is external storage indicators, which show how much storage is being used in its series of LEDs.)
RAID 5 - Space cost of any one of the identical disks in the array. (So four 250GB drives yields a 750GB array, raw.)
Drobo - Space of the largest disk in the array. (So two 250GB drives and two 500GB drives yields a 1TB array, raw.)
RAID 5 - Format any file system.
Drobo - HFS or NTFS. (Limited FAT32 support, future file systems to be added.)
RAID 5 - If a drive dies your array is at risk and goes into rebuild mode when you swap out the bad disk. Depending on your RAID array, you may or may not be able to use it during rebuild. Alternately, if a drive starts writing corrupt data, that data may stay corrupt, with backup recovery being your only option of restoration.
Drobo - If a drive dies your array still goes into rebuild mode, but your data may still be protected. Depending on how much capacity you're using, if there's enough free space in the array, your Drobo may still be able to ensure full redundancy. (Again, thank that block-level aware array system.) If your Drobo doesn't have enough free space during a disk loss, your data will be at risk; after inserting a new drive it will go into rebuild mode, but will still continue to be available.
RAID 5 - Users must back up contents and replace their entire array of drives to increase array storage. (Read: no drive recycling.)
Drobo - Upgrade storage a drive at a time. If you have empty bays, simply insert a new drive -- that storage is instantaneously available. If you are out of bays then remove smallest drive and add its larger replacement. Once that array is rebuilt and the new storage is available, remove the next smallest, etc. until you've reached the capacity you desire. Drobo can support 4TB+, and can supposedly address an infinite amount of space as drives push past the 1TB mark.
So it's pretty easy to tell that there are some very distinct advantages for users who aren't attached to the idea of RAID. The usability of a virtualized storage system is a powerful proposition -- especially considering that it's even possible to make backups with entire sets of drives. (Simply turn off your Drobo, remove all drives, and store them away. If you want to recover the data, just put them all back in, the Drobo is aware they are a Drobo drive array and picks up where the set last left off.) Some of these capabilities may not seem too foreign to those familiar with Infrants products, namely those featuring X-RAID (which seems to be that company's take on virtualized storage).
Excepting the defective first unit we got -- which worked fine other than a wire which came loose inside the box and ground up against the fan, making a hideous noise -- our Drobo has worked very well. Upgrading its firmware is dead simple just use the desktop app and it's all done for you. And unlike many external devices, you don't need to install the Drobo desktop software to use the device. It's just a mass storage drive, all the software does is break down how your storage is being used, give diag info, etc.
The unit itself is always cool to the touch, and more than often quiet. When its fan does engage, it doesn't seem to get unbearably loud, but we still wouldn't want it in our bedroom. Data rates are acceptable -- we averaged 12-15MBps write throughput during large file transfers. Drobo promised "mid-range" performance, and that's what it delivers. (In other words, don't expect this thing to carry your data center.)
However, Drobo isn't without issues. As advanced and advantageous virtualized storage is, for most users it's going to be a pretty confusing experience, and that may never change. The guy who thinks his Drobo can handle having two drives yanked out at the same time is going to be in for a sad surprise. We thought our 1/3rd-full 1TB array would be totally happy about us yanking the smallest drive and upgrading it to something a bit larger -- and it was, 7 hours later after rebuilding. Unfortunately, only adding new drives to empty bays is a fast process -- upgrading existing ones can take a while, and be nerve-wracking if your array doesn't have enough space to keep things redundant during the rebuild. And that's when you'll most notice the bright, blinking lights on the front of the unit, which can't be shut off, even during normal use.
Finally, we'd friggin' kill for this thing to be a NAS box. We know that it's not, but it should be. We can live with the fact that it doesn't have a lot of extraneous inputs (really, it's true, most users probably don't need anything faster than USB 2.0 -- few consumer drive arrays can read/write faster than 800Mbps anyway), but needing to have the Drobo live behind a PC or Airport Extreme router in order for it to be network capable is just so unfun. It's counterintuitive to have a massive storage array that is only easily accessible via a single PC -- unless that PC is set up to serve. At this point in the came it's not unfair to expect your storage array to be smart enough to serve its own content, and a Drobo with an internal DLNA media server and an Ethernet port would totally have blown our minds.
Let's finish this thing off: do we like the Drobo? Yes, absolutely, we think it's great. We heartily endorse it -- but as with any kind of relatively new technology, users need to be aware of its limitations and how it does business differently from other similar devices on the market. If you can get past the fact that your drives won't be living on the network, there are many wonderful surprises about the Drobo. It's not a hard call for us -- no way we're going back to a RAID array after using one of these.