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Caption by: Alan Stevens
The ever-growing family of Data Robotics storage appliances now includes the Drobo Elite, which is aimed at small to medium-sized companies looking to consolidate server storage. It's not completely new, as it's based on the same chassis and self-managing BeyondRAID technology behind other Drobo products. The Elite model adds dual Gigabit Ethernet ports and dedicated iSCSI support for IP SAN deployment.
Drobo Elite is based on the same chassis and BeyondRAID technology as the Drobo Pro
At first glance the Drobo Elite doesn't seem that much different from other mid-range storage arrays. Housed in the same shiny black casing as the Drobo Pro, it can be desk mounted or placed in a rack using the supplied brackets. A single integrated power supply keeps it running, with temperature-controlled fans for cooling and slots for up to eight 3.5in. SATA hard disks.
Unlike most of the competition, however, the disks that go inside the Drobo Elite can be from any vendor. You can also mix together disks of any capacity and any spin speed — the only exception is solid-state (SSD) drives, which are not yet supported.
Installation is another big differentiator, and it's impressively straightforward. Just slide the disks into place — no special carriers or cables are required — and the BeyondRAID firmware will automatically work out how best to configure them to provide an optimum balance between capacity and data protection. You can start with just two disks, although at least three are needed to get the equivalent of RAID 5 protection, enabling the Drobo Elite to carry on working even if one of the disks fails.
In the event of a disk failure, all you have to do is swap the failed drive for a new one and the data will be rebuilt, automatically. You can also plug in extra disks at any time to add more space or swap an existing drive for something bigger and/or faster. Unlike with a conventional array, there's no need to backup the data and restore it again to enable this to happen. It's all done for you, the exception being if you want to protect against two disks failing at the same time (RAID 6). Even then, it's just a matter of ticking a box in the supplied Dashboard management tool and leaving BeyondRAID to take care of it.
Drobo Elite accepts up to eight 3.5in. SATA hard disks, in any combination of capacity and spin speed
We found it all ridiculously easy. Indeed, the only faintly technical setup required was to configure the so-called Smart Volumes ready for connection to servers via iSCSI. Up to 255 volumes can be defined compared to just 16 on the cheaper DroboPro, with the maximum size dependent on the file system involved; volumes of up to 16TB are possible when using Windows NTFS.
The BeyondRAID technology takes care of just about everything, assigning blocks to the virtual Smart Volumes as required rather than pre-allocating storage in advance — a technique known as thin provisioning. As a consequence it's possible to configure more storage than is physically installed in the array, which could become an issue as the Smart Volumes fill up. But then you can always plug in larger hard disks should extra 'real' capacity be needed.
Another plus is the allocation of storage from the common disk pool rather than assigning specific drives. Added to which BeyondRAID will return deleted blocks to the pool for maximum utilisation of the available space.
The Drobo Elite has a pair of Gigabit Ethernet ports at the back to connect servers
With two Gigabit Ethernet ports at the back, the Drobo Elite offers plenty of bandwidth over which to connect servers — or desktop PCs, if required. All that's needed is a suitable iSCSI initiator, which can be the one included as standard with Windows Server 2008, Vista and Windows 7; on Apple Macs, the Drobo Dashboard will install a custom initiator with additional support for Linux and VMware initiators. Minimal setup is required regardless of platform, with optional LUN-level CHAP authentication also available if needed.
For maximum performance, a dedicated network switch connecting servers to the Drobo Elite is recommended. The results you get will also depend on the disks used, in addition to what's in the host servers. However, even with a relatively modest dual-core Xeon system (typical of those sold to small businesses) we were impressed with what we saw.
For our tests we loaded three 1GB hard disks into the Drobo Elite and configured a single 16TB NTFS partition. This we attached to a server running Windows Server 2008 before running a variety of throughput tests using the open-source Iometer tool. Raw performance was impressive, peaking at 112MB/s when reading large sequential data blocks — close to what the single Gigabit interface in our server could handle. Disk writes and random read/writes were somewhat slower, but real-world file copies were almost as fast as from direct-attached disks, as was streaming of video files from the Drobo Elite array.
On the downside, there was a drop in performance when we simulated a disk failure by removing one of our drives. That's to be expected, though, and overall this is an impressive bit of kit. It's not cheap, but apart from that our only real concern is the lack of built-in backup tools to take advantage of the USB interface — otherwise only used for initial setup. That's not a big issue, and the DroboElite more than fulfils its role as an idiot-proof iSCSI SAN appliance for small to medium-sized businesses.
Caption by: Alan Stevens
Caption by: Alan Stevens