Drobo Mini review: An underperforming and overpriced storage device

With the Mini, Drobo makes Thunderbolt storage more complicated and more expensive than it should be.

Dong Ngo

Dong Ngo

SF Labs Manager, Editor / Reviews

CNET editor Dong Ngo has been involved with technology since 2000, starting with testing gadgets and writing code for CNET Labs' benchmarks. He now manages CNET San Francisco Labs, reviews 3D printers, networking/storage devices, and also writes about other topics from online security to new gadgets and how technology impacts the life of people around the world.

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14 min read

The Drobo Mini is like no other Thunderbolt storage device I've reviewed before. For one, it's very compact, yet its four drive bays mean it can host up to four 2.5-inch hard drives. Secondly, it's the first multiple-bay Thunderbolt storage device that also supports USB 3.0, and the first Thunderbolt device I've seen that offers a ceiling storage space of up to 16TB, despite having just 4TB of actual raw storage at most, thanks to Drobo's flexible BeyondRAID setup.

Drobo Mini

Drobo Mini

The Good

The <b>Drobo Mini</b> is compact, can host four drives with dynamic storage scalability and protection, and supports both Thunderbolt and USB 3.0, and its drive bay design is excellent.

The Bad

The Drobo Mini is very expensive, it's comparatively slow, hot, and noisy, it takes a long time to start up, and overall it's cumbersome to use.

The Bottom Line

The esoteric Drobo Mini seems to strive to be unique mostly for the sake of uniqueness, and offers very little, if at all, in terms of usability considering its crazily high cost.

And finally, it's got a slew of unique little features including an mSATA drive bay, a built-in emergency battery, a cool magnetic drive bay door, and many colorful LED status lights. There's also a little bit of money-saving: like most recent Thunderbolt storage devices, the Drobo Mini comes with the necessary Thunderbolt cable included.

On the down side, at the time of the review, the Drobo Mini bears a crazy price tag of $650 with no storage included; it takes a long time to start up; and it's noisier than most Thunderbolt devices I've worked with. In terms of performance, when hosting four high-speed 2.5-inch hard drives, the drive fell short in my testing when compared with its peers, using both Thunderbolt and USB 3.0 connection types.

That said, if you don't mind spending money on uniqueness, the Drobo is available now, though you won't find it at Apple's store, where you'll find most other Thunderbolt storage products. For productivity, remember to also check out the alternatives on this list. For example, for just $500 the WD My Book Thunderbolt Duo offers slightly faster overall speeds, 6TB (or 3TB protected) of storage space, and a much more straightforward experience.

Measuring 7.3x1.8x7.1 inches, and weighing just about 3 pounds (with the four drive bays fully loaded), the Drobo Mini is the most compact four-bay storage device I've seen. This is mostly because it's designed to house 2.5-inch laptop hard drives and not the regular 3.5-inch desktop hard drives. The Drobo Mini is not exactly "the size of a deli sandwich" as described on Drobo's Web site, however; rather, it's about the size of a Mac Mini, slightly thicker and heavier, in fact.

The Drobo Mini comes with a crazy number of bright LED lights on the front that can be fun or annoying depending on your mood.
The Drobo Mini comes with a crazy number of bright LED lights on the front that can be fun or annoying, depending on your mood. Dong Ngo

On the front, the Drobo Mini's drive bays are covered by a magnetic lid that stays on easily and firmly. It's a little hard to remove this lid, however, mostly because it's very smooth and kind of slippery, and there's no handle to grab. You just have to jiggle it around and eventually it'll come off, revealing the four drive bays. Each of the bays can host a 2.5-inch standard high-speed drive, be it a hard drive or solid-state drive (SSD). Since standard high-speed 2.5-inch drives on the market are currently capped at 1TB, the Drobo Mini offers up to 4TB total of raw storage space, or 3TB of usable capacity with data protection. The drive bay can house a drive that's either 9mm thick (standard) or 7mm thick (ultrathin).

It's very easy to insert a drive or remove it from its bay; no tool is necessary, since each drive can be pushed in its place. To remove it, you just push again and it will come out. This is very similar to how you use an SD card with most digital cameras, which is as well-designed as can be.

Wrapping around each of the drive bays is a bright LED light that stay green when everything is in order. When something happens, such as a drive has crashed (or was pulled out during an operation), the color of the light will change to red. During a RAID rebuild, all of the lights of the four drive bays will be flashing green and amber. This is a helpful feature when something is not right. Most of the time, however, I find these lights too bright and they can be an annoyance when you want to keep the room dark. Especially considering that the Drobo Mini has even more lights.

It's true: also on the front, at the bottom edge, the storage device has three more LED lights, two little ones that show the power status (always green) and activity (flashing green), and a long blue light that works as a storage gauge: from left, it partially glows brighter to indicate how much of the total capacity has been used up. As you can imagine, all these lights make the front of the Drobo quite busy to look at, especially while the drive is starting up, when these lights are constantly flashing or changing colors or both. The good news is you can use the Drobo Dashboard software to dim these lights.

And the Drobo Mini takes a long time to start up, ranging from 1.5 minutes to a whole 4 minutes in my trials. Other Thunderbolt storage devices take just a few seconds to be ready. This in itself could make the drive a terrible choice as an external storage device when you are in a hurry.

On the back, the Drobo Mini has two ventilation fans on both of its sides. These fans run all the time starting from the moment you turn the drive on, and they're noisy. In fact, the Drobo Mini is the noisiest compact storage device I've used, rivaling even the Pegasus R6, which is a huge device, about six times the physical size of the Drobo Mini. Again, together with the excessive number of LED lights on its front, the Drobo Mini's noise could really be a nuisance for many users.

Also on the back, the drive has two Thunderbolt ports (which is standard for most Thunderbolt storage devices), a USB 3.0 port, a power port, and a power on/off button. It's important that you use this power button to turn the drive off. This is because if you unplug the drive from the power source, it won't turn off right away. The Drobo comes with a built-in battery that keeps it alive when the power goes out spontaneously, "for the data to be written to nonvolatile storage," according to Drobo. While this seems like a good data protection feature, in my trials it was, again, more of a nuisance.

The Drobo Mini comes with an mSATA SSD bay on the bottom, which may inspire you to spend more money on a feature that promises to boosts the drive's performance.
The Drobo Mini comes with an mSATA SSD bay on the bottom, which may inspire you to spend more money on a feature that promises to boosts the drive's performance. Dong Ngo

When I unplugged the power to the drive to simulate a power blackout, the device would stay on though its fans turned off immediately, but it was also immediately dismounted from the computer, as though its Thunderbolt cable were unplugged. To be clear, if you are working on a file or copying data to the drive and the power goes out, the data will still be lost. Now when I plugged the power back in, the drive would turn back on with fans back on loudly, but would not be recognized by the computer for a few minutes; then it appeared to restart by itself, so would be another few minutes before it was back to normal. From the users' point of view, the built-in battery is quite useless and seems to only make life harder.

In addition to the four drive bays on the front, the Drobo also has an mSATA SSD drive bay on the bottom where you can install an mSATA SSD. Drobo calls this bay the Accelerator Bay, claiming that it will boost the performance of the Mini when an mSATA SSD is used. Whether this performance boost happens is to be determined -- I didn't try that out -- but for sure this will increase the total cost. On a good day, a 64GB mSATA SSD can be as cheap as $70, but larger drives will cost significantly more.

Setup and features
Generally, there's basically nothing to the setup process of a Thunderbolt storage device. For most of them, you just have to plug the drive into a power outlet and the computer, using a Thunderbolt cable, and that's it. Within a few seconds you can use the drive. With others, you might have to format the drive using the Disk Utility (Mac) or Disk Management (Windows), a process that takes less than a minute to do.

It's quite different with the Drobo Mini.

Out of the box, the Drobo Mini comes with no storage, but Drobo shipped the review unit with four 750GB Seagate Momentus 2.5-inch hard drives for me to use in testing. These are high-speed laptop drives that spin at 7,200rpm. It was easy to install these drive in the Mini's four drive bays, as mentioned above. The Mini also comes with a standard USB 3.0 cable and a foot-long Thunderbolt cable.

The Drobo Dashboard software shows the Drobo Mini's status in sync with the drive's front LED status lights.
The Drobo Dashboard software shows the Drobo Mini's status in sync with the drive's front LED status lights. Dong Ngo

Using the drive as an external storage drive, however, required many more steps. First I had to download the Drobo Dashboard software from Drobo's Web site. During the installation of the software, it suggested that I cancel the process and install Java first, which I did. After that, I reinstalled the software from the beginning, and had to restart the computer to complete the installation.

The software took about 30 seconds to recognize the fully started-up, plugged-in Drobo Mini and took about 5 minutes to format it into HFS+. Now there was something interesting about this process. The Dashboard software, by default, suggested that I should pick 16TB as the total storage space of the Drobo Mini, while in fact with the four hard drives, it has at most 3TB of raw storage space. As it turn out, with Drobo's BeyondRAID, you can choose ceiling storage space of anywhere between 1TB and 16TB, regardless of the actual capacity of the Mini. As you use the drive, and the actual storage space runs out, you can then add more storage either via more drives (if you started with fewer than four drives) or via drives of larger capacities, up to the amount determined by the ceiling volume. Given that, there seems to be no benefit to picking less than 16TB as the initial volume size.

But there's no benefit to picking the highest amount, either, since each of the Mini's four drive bays supports a drive of 1TB at most. For that reason, it's kind of pointless to select a volume that's larger than 4TB. Having a "virtual" volume that's larger than the actual storage space can also be confusing since you end up thinking you have more storage that you actually do. Our review unit, with four 750GB hard drives, actually offers about 2TB of protected storage space with one-disk redundancy, or 1.3TB with dual-disk redundancy.

The formatting process required the computer to restart one more time before the drive is usable. So all in all, if everything goes well, you'll spend about 5 minutes downloading and installing the Drobo Dashboard software, another 5 minutes on formatting the drive, and have to restart restart the computer twice, to complete the setup process for the Drobo Mini. This isn't really that long of a process, unless you compare it with setting up any other Thunderbolt storage device.

Technically, it seems you can just ignore the Drobo Dashboard software and use Disk Utility to format the Mini the way you would with other drives. But doing that would mean you can't take advantage of BeyondRAID, which is the strong point of the drive and is the only option the Drobo Dashboard software gives you. You can't use the software to set up the Drobo Mini using a standard RAID setup, such as RAID 0, RAID 1, RAID 10, or RAID 5. (For more about RAID, check out this post.)

In my trials, BeyondRAID worked as intended, though I didn't get the chance to test all it could do. This is because I didn't have any internal drive larger than 750GB on hand at the time of testing. In fact, there aren't many 1TB 2.5-inch drives on the market that spin at 7,200rpm. Nonetheless I was able to remove one of the hard drives and replace it with another of the same capacity without having to power down the Drobo Mini, something RAID 5 or RAID 1 storage devices also offer. The Drobo Mini took about 20 minutes to add a new drive in my trials with about 60GB of storage space being used. Note that the RAID rebuild time varies a great deal depending on the amount of existing data, the more data, the longer it takes. During this rebuild time all the status light were going wild, continuously flashing different colors, and the Drobo Dashboard software gave me warning instructions. In the end the operation was a success. The Drobo Mini is the only Thunderbolt storage device that offers the option of scaling up its storage space dynamically this way. With other multiple-drive Thunderbolt storage products, such as the Pegasus R6 or the WD VelociRaptor Duo, you can hot-swap existing drives but can't scale up the drive's storage space.

The Drobo Mini isn't a superslow external storage device, but overall it's the slowest among all multiple-bay Thunderbolt storage devices I've reviewed.

To be fair, it's the only multiple-bay Thunderbolt storage device that uses 2.5-inch (laptop) hard drives, while the rest use the larger 3.5-inch hard drives, which tend to be faster. On the other hand, however, the Drobo Mini was tested with four high-end Seagate Momentus 750GB hard drives (model ST9750420AS) that spin at 7,200rpm and are faster than some 3.5-inch hard dives used in other Thunderbolt storage solutions. The WD My Book Thunderbolt Duo, for example, uses two 3.5-inch WD Green hard drives -- designed with more focus on energy conservation than speed -- that are likely slower than the Seagate Momentus, individually.

The Drobo Mini uses 2.5-inch hard drives, which might or might not be the reason why its performance is not on par with 3.5-inch-based Thunderbolt storage devices.
The Drobo Mini uses 2.5-inch hard drives, which might or might not be the reason why its performance is not on par with that of 3.5-inch-based Thunderbolt storage devices. Dong Ngo

Every internal drive on the market, be it a hard drive or an SSD (which caps by the speed of SATA 3 -- 6Gbps -- at most), by itself is much slower than the Thunderbolt standard, which caps at 10Gbps. That said, many multiple-bay Thunderbolt storage devices, such as the Pegasus R6,or the WD VelociRaptor Duo, are able to aggregate the speed of individual drives into a faster combined speed. I expected similar performance from the Drobo Mini, especially after all the hype Drobo has for it in terms of performance, but it didn't really deliver.

I tested the drive both against other Thunderbolt storage solutions (and internal drives) and against other external drives, including USB 3.0 drives. The test machine is a late-model 2011 MacBook Pro, running a high-end SATA 3 SSD. The Drobo Mini was tested only in BeyondRAID with one disk redundancy, which is similar to RAID 5, since this is the default option and generally offers faster performance than the dual-disk redundancy, similar to RAID 1. All of the tests were performed by timing with a stopwatch how long the drive took to finish a heavy data transfer job. The scores in all of CNET's storage reviews are those of real-world sustained speeds. Let's check how the Drobo Mini performed.

Tests against other Thunderbolt devices and internal drives
These are the test where the Drobo Mini was stacked against other Thunderbolt storage devices and internal drives. The reason internal drives (mostly SSDs) are thrown in to the mix is because prior to Thunderbolt, they are the fastest storage devices on the market, so it's just natural to use them to show how much faster Thunderbolt can be. Like all other Thunderbolt storage devices, the Drobo Mini had to go through two rounds of testing.

In the first, called "Self read and write," I copied data within the drive, from one folder to another. In this test it scored just 45MBps. In this same test, the WD My Book Thunderbolt Duo scored 77MBps and 40MBps in RAID 0 and RAID 1, respectively. The Pegasus R4, a RAID 5, four-bay drive, scored 101MBps in this test.

In the second test, call "Unit to unit," the Drobo Mini was set to copy data from another Thunderbolt storage device. This test is to show the drive's best possible write performance. I picked the high-end WD VelociRaptor Duo, formatted in RAID 0, as the source of the data to make sure the source is not the bottle neck. In this test, the Drobo Mini scored 101MBps, while the WD My Book Thunderbolt Duo scored 101MBps and 168MBps in RAID 0 and RAID 1, respectively. The R4 scored 240MBps in this test.

Thunderbolt vs. Internal hard-drive performance (in MBps)
(Longer bars indicate better performance)
Unit to unit   
Self read and write   

Promise Pegasus R6 (RAID 5)

Plextor PX-256M2S

OCZ Vertex 3

Crucial M4

LaCie Little Big Disk SSD

OCZ Agility 3

Patriot Wildfire

WD VelociRaptor 600GB

Elgato Thunderbolt SSD

Seagate Barracuda XT

WD VelociRaptor 300GB

Drobo Mini

Note on the chart how the Drobo Mini was significantly slower than most others. In fact, it's by far the slowest non-RAID1 Thunderbolt RAID system to date. Generally, Thunderbolt storage devices with RAID 0 or RAID 5 (which is similar to how the Mini's BeyondRAID was set up for the test), are at least on par or faster than internal SSDs, but the Drobo Mini couldn't manage to outdo the WD VelociRaptor regular hard drive in terms of data rate.

Tests against external drives

In this set of tests, the Drobo Mini was tested the way it's most likely to be used in the real world: transferring data back and forth between itself and a computer. For this test, when using the Thunderbolt connection, the Mini scored 106MBps for writing, making it almost the slowest among Thunderbolt storage devices, including single-volume ones. In reading, it did even worst at 95MBps, clearly the slowest I've seen. Generally, multiple-bay storage devices that are not using RAID-1 are faster than single-volume storage device, in the case of the Drobo, it could barely keep up with even the Buffalo MiniStation HD-PATU3, which is a Thunderbolt portable drive that's based on a single internal 2.5-inch hard drive.

When used with a USB 3.0 connection, the Drobo Mini was much slower, at 59MBps and 77MBps for writing and reading, respectively, making it the slowest USB 3.0 storage device to date.

Data transfer (TB vs. external, in MBps)
(Longer bars indicate better performance)

Promise Pegasus R6 (RAID 5)

LaCie Little Big Disk SSD

Promise Pegasus R4 (RAID 5)

LaCie Rugged Thunderbolt

Elgato Thunderbolt SSD  

Drobo Mini (via Thunderbolt)

Drobo Mini (via USB 3.0)

All in all, in terms of data speed, the Drobo Mini is unimpressive and falls to a new performance low for both Thunderbolt and USB 3.0 storage devices. I also noticed something troubling: the drive seemed to become progressively slower the more data it stored. For example, when the drive was 1.5TB full, out of its 2TB protected storage space, it scored just 85MBps for writing when copying data from the MacBook Pro test machine, though it managed 106MBps at this job earlier when it was empty. Judging from the performance alone, I can't help but feel there's something not right about the BeyondRAID itself. Unfortunately there was no option to make the Drobo Mini work in any of the standard RAIDs.

I also noticed that the Drobo Mini became hot very fast and remained hot during operation. It wasn't hot enough to cook an egg on, but it was definitely the hottest of the Thunderbolt storage devices, despite those loud ventilation fans.

Unfortunately, the Drobo Mini over-complicates external storage. It offers very little in real-world benefits and in the end, users pay too much for the simple privilege of owning something that's different. There are four important factors when it comes to getting an advanced storage system: performance, ease of use, price, and data protection. While in theory the Drobo Mini might offer a relatively new way to protect and scale up your data, it categorically and miserably fails on the rest, making it not only a waste of money but also a waste of time.

Drobo Mini

Drobo Mini

Score Breakdown

Setup 5Features 7Performance 4Support 7
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