Drobo's direct-attached and network-attached storage units are quite popular in the market, but we never got the opportunity to evaluate them on AnandTech. At CES 2016, we met with Drobo and got pitched with the advantages of Drobo's BeyondRAID technology. In this review, we take a look at how BeyondRAID is used in one of their most popular DAS units - the Drobo 5D.

Introduction

Drobo makes a variety of external storage devices for both consumers and businesses. These fall under both direct-attached and network-attached categories. Their first product appeared in the market in 2007, and since then products have been released regularly. I will not go into the details of Drobo's history, as Wikipedia has more than enough interesting information about how Drobo has evolved over the years.

One of the major selling points of Drobo's products (compared to the competition) is the usage of a proprietary patented method to provide resiliency against disk failures. We will briefly discuss this feature (called BeyondRAID) further down in this section. Prior to that, let us take a look at the specifications of the Drobo 5D.

Drobo's products have a long life cycle. In fact, the Drobo 5D DAS was introduced back in late 2012, and it is still available in the market and receiving firmware updates.

Hardware Aspects

Compared to the average multi-bay direct-attached storage solution, the Drobo 5D has two interesting features - the first one is the presence of two Thunderbolt ports on the unit in addition to the USB 3.0 device port. The second is the presence of a mSATA SSD slot on the underside of the unit. It can be used for data-aware tiering, i.e, caching of 'hot' data.

The Drobo 5D employs premium packaging. In addition to the 150W (12V @ 12.5A) power adapter, USB 3.0 cable and the quick start guide, the main unit comes in a tote bag. The all-metal chassis has rounded edges can be aesthetically pleasing, away from other sharp-edged designs: the five 3.5-inch drive bays are covered by a magnetic lid and installing disks is a tool-less operation. After moving the latch to the side, the drives slot right in, and the latch automatically snaps back in to keep the drive in place / prevent accidental removal. A spring mechanism at the inner end ensures that taking out the drives is a simple matter of just moving the latch to the side.

The mSATA slot is accessible from the underside of the chassis and is also controlled by a latching mechanism. A sticker strongly advises users to install the mSATA module only after completely powering down the system. The mSATA SSD is held in place by a couple of notches that slot into the holes usually reserved for screws. In fact, the Drobo 5D chassis is extremely user-friendly - there is absolutely no need for a screwdriver, and, in fact, there are even no tool-less screws to deal with.

Moving on to the chassis itself, we have indicator LEDs to the right and bottom of the front lid. The rear side of the lid provides a guide to the statuses indicated by the various colors. As is usual, the ports and switches are all on the rear side of the unit. A 120mm fan is housed behind the perforated rear panel to provide ventilation. There are two Thunderbolt ports to support the usage of the unit as part of a daisy-chain configuration. Unfortunately, it works only with compatible Apple products. A USB 3.0 Type-B female port, a power inlet and an explicit power on/off switch make up the rest of the rear panel. The gallery above shows the various external hardware aspects of the Drobo 5D.

Even though we didn't do a full-length teardown of the unit, the firmware file points to a Marvell ARMADA XP platform in the Drobo 5D. The Thunderbolt ports are obviously enabled by Intel DSL3510 controller.

Drobo Dashboard and BeyondRAID

In our initial setup, the Drobo 5D was loaded up with 5x 2TB drives and booted up after connecting over USB 3.0 to our DAS testbed. Windows Disk Management reported a 64TB physical disk which could be formatted in NTFS and used without hiccups on any other Windows system. Obviously, the 64TB capacity is virtual. In order to get a look at the actual usable capacity, and check up on the status of the disks in the unit, Drobo supplies the Drobo Dashboard, a tool for central management of all Drobo devices on the network / directly attached to the PC on which it is installed. The gallery below shows the various features of the Drobo Dashboard and the administration tasks that can be executed using it.

The Drobo Dashboard allows the Drobo 5D to be setup with single- or dual-disk redundancy, the former being the default. For people coming from a RAID background, this is similar to RAID-5 or RAID-6 (coming with similar requirements in terms of number of disks required). The Dashboard also presents the total usable capacity, based on the capacity of the disks in the unit. Other operational aspects are pretty much evident from the gallery pictures.

BeyondRAID is the data protection scheme used by Drobo. It is a patented proprietary scheme unlike traditional software RAID (mdadm etc.). ArsTechnica has a detailed look into the patent behind BeyondRAID for those interested in the technical details of how BeyondRAID works. One of the main disadvantages of this proprietary scheme is that it is impossible for third-party tools to reconstruct data in case of a faulty unit. Unless the user has a standing warranty coverage from Drobo, getting hold of another similar Drobo unit is the only way out.

One of the advantages of BeyondRAID over some of the other RAID implementations is that disks of varying sizes can be used. This is similar to mdadm-based implementations like Synology Hybrid RAID (SHR). In the case of single-disk redundancy, the largest capacity disk is completely used up for protection purposes. For dual-disk redundancy, the two largest disks are used up and don't contribute to the usable capacity.

We evaluated the Drobo 5D in both single-disk and dual-disk redundancy modes. In both cases, we also processed benchmarks in two modes - with a mSATA SSD in the hot-cache drive bay and without it. Five 2TB Toshiba enterprise SATA hard drives (MG03ACA2SATA) were used along with a Plextor 256GB M5M mSATA drive for benchmarking purposes. In the next section, we take a brief look at our testing setup, evaluation methodology and testing results.

Direct-Attached Storage Performance

Evaluation of DAS units on Windows is done with the testbed outlined in the table below. We had started evaluation with the older Haswell-based testbed, since it has Thunderbolt 2 support. Eventually, we learnt during the course of evaluation that the Drobo 5D's Thunderbolt ports are useless when the unit is used with PCs / Windows. Despite this, we continued and completed our evaluation using the USB 3.0 interface on the same testbed. We utilize the USB 3.0 port directly from the Z97 PCH.

The full details of the reasoning behind choosing the above build components can be found here. The list of Drobo 5D configurations used for comparison purposes is provided below.

• Drobo 5D SDR Yes mSATA (Single disk redundancy with mSATA acceleration)
• Drobo 5D SDR No mSATA (Single disk redundancy without mSATA acceleration)
• Drobo 5D DDR Yes mSATA (Dual disk redundancy with mSATA acceleration)
• Drobo 5D DDR No mSATA (Dual disk redundancy without mSATA acceleration)

In the real-world work traces, we can see the real benefit of the mSATA SSD cache acceleration. Writes don't benefit much, but, in the read workloads, we can see that the mSATA SSD-enabled configurations often provide almost double the performance of a raw hard-drive array.

Miscellaneous Aspects and Concluding Remarks

The single 120mm fan is a reasonable solution to balance the need to cool down five SATA hard drives while also maintaining an acceptable noise profile. We noticed many reviews online indicating fan noise to be an issue in the Drobo 5D. However, we had no such issues with our review unit.

One of the advantages of the Drobo 5D / BeyondRAID is that users can start off with just a single drive in the unit, and add more drives down the line. The RAID expansion / migration process is seamless and without data loss. The progress of this process can be monitored with the Drobo Dashboard. Similar to our NAS reviews, we first started off with one 2TB drive in the unit, and added a second one after some time. Since the unit was configured in single-disk redundancy mode, the unit took some time to ensure that the second disk could act as a protection disk. However, due to the nature of BeyondRAID, the addition of new disks (3 through 5) resulted in immediate expansion of usable capacity. We also tested out moving to a dual-disk redundancy configuration once the five disks were in the unit. This took some time similar to the shift from one disk to two disks inside the unit. The power consumption of the unit was also tracked in the course of this evaluation routine. The numbers are summarized in the table below. These numbers are without a mSATA drive in the cache acceleration bay.

Coming to the business end of the review, we must first give credit to Drobo for creating a really simple and easy-to-use product for the average consumer. The whole operation (from installing drives, to actually mounting the volumes on a computer) is very easy, and can be managed even by folks who are not particularly adept with computers. The mSATA SSD acceleration is very helpful for multimedia editing directly off the Drobo 5D, particularly for read operations. The effectiveness was brought out by using real-world storage benchmark traces from Photoshop and similar programs. The dual-disk redundancy configuration benefits more from the SSD acceleration compared to the single-disk redundancy configuration.

There are a few points that could help Drobo expand the reach of units such as the Drobo 5D:

• Thunderbolt support in Windows (if not for the 5D, at least for future products which integrate Thunderbolt support)
• Support for data recovery by the end-user

To expand upon our second suggestion, it is well known that disks making up RAID volumes in commercial off-the-shelf NAS units can be mounted on a PC to access the data. We would like Drobo to provide a software program that can mount Drobo volumes if the disks used in a Drobo device were to be connected directly to a PC. This would go a long way in clearing the air of distrust that many tech-savvy consumers have when considering proprietary data protection schemes like BeyondRAID.

The Drobo 5D is currently available on Amazon for $615. The price is not a surprise, given that the product's features (Thunderbolt support) and operation make it attractive to people in the Apple ecosystem. As a Thunderbolt / USB 3.0 device with a novel and easy-to-use data protection scheme, the pricing is reasonable. However, from the viewpoint of a PC user, it is just a USB 3.0 device. There are many hardware RAID solutions with a USB 3.0 port that provide much better performance. But, there is definitely a segment of the market that doesn't mind paying a premium for Drobo's simplicity and 'it just works' aspects.