Disk storage can be attached to a server in a couple of ways, either directly (internally or externally) or via a dedicated Storage Area Network (SAN). Traditional SAN technology uses Fibre Channel hardware to link servers and storage together but in recent years there’s been a move to cheaper commodity Ethernet to provide the infrastructure, running a protocol called iSCSI?collectively, known as an IP SAN.
Whether Fibre Channel or iSCSI based, a SAN allows storage to be centrally managed and virtualised with support for multiple virtual volumes on an array each connected to different host servers. These virtual volumes can then backed up, resized and moved from server to server, with minimal downtime and no need for any re-cabling. They can also be quickly switched between servers to support fast failover in clustered setups.
On the downside SAN storage can be both expensive and difficult to manage, issues Data Robotics is claiming to address with the latest member of its Drobo storage family, the DroboElite.
What is it and who is it for?
Housed in a shiny black casing with optional brackets for rack mounting, the DroboElite is an IP SAN storage appliance aimed at small to medium-sized businesses looking to consolidate storage across multiple servers. Up to eight ordinary SATA disks can be plugged into the appliance with two Gigabit Ethernet interfaces at the back for high bandwidth connectivity using iSCSI. Maximum raw capacity is 16TB (using 2TB disks) with virtualisation built in to support up to 255 logical volumes.
Unlike most other SAN storage arrays, very little technical knowledge is required to deploy or manage the DroboElite which employs a proprietary technology called BeyondRAID to automatically organise and protect the data held on the disks it contains.
Add a new disk and it’s formatted and added to the available storage pool automatically. Moreover, should one of the disks fail the array can carry on working and the missing data rebuilt when a replacement is plugged in. Dual-drive redundancy is a selectable option and, because it’s iSCSI the Drobo appliance can be easily shared between servers running Windows, Mac OS/X and Linux.
Pricing & setup
With a recommended price of £2179 (ex. VAT) the DroboElite is far from cheap, but then Data Robotics has clearly priced its new Elite appliance to compete against other dedicated iSCSI products. Bear in mind too the need to factor in the disks, which aren’t included in the price. A set of eight 2GB SATA disks can be had for around £800 (ex. VAT), but that’s for standard desktop drives?more reliable server disks with higher spin speeds are likely to cost a lot more. Technical support, beyond what’s included in the standard warranty, is also extra.
Deploying the DroboElite is a game of two halves, the first of which?configuring the hardware?is a piece of cake. Simply plug some disks into the Drobo chassis (no special carriers, screws or mounting plates are needed) and the BeyondRAID firmware will automatically format them and decide on the best protection scheme to apply. And it doesn’t matter if you mix disks from different vendors, with different capacities or spin speeds?they’re all grist to the BeyondRAID mill.
What little setup work there is can be done by first connecting the Drobo to a PC using the USB cable provided then loading up the Dashboard utility also included in the box. This lets you define the so-called Smart Volumes and also set the iSCSI parameters?the only time things get faintly technical.
That done the DroboElite can be connected to the LAN using the two Gigabit ports provided and network attached servers or even PCs configured to access the storage it provides. The iSCSI initiator included in Windows Server 2008, Vista and Windows 7 works just fine here. Otherwise the Drobo Dashboard can install initiators for both earlier versions of Windows and Apple Mac systems. Linux, initiators are also supported.
Does it do it well?
As with other Data Robotics products, by far the biggest selling point of the new DroboElite is the almost total lack of any need for hands-on management. Sure, it takes a few minutes to get up and running, but on a day to day basis all that’s needed is to keep a weather eye on the traffic-light LEDs to make sure the array isn’t running out of capacity or developing a fault. Even then, all you have to do is pop in a new drive or swap a failing disk for a new one. Everything else is done automatically.
On the performance front too, the DroboElite is impressive with two Gigabit Ethernet ports both of which can be configured as iSCSI targets. Overall throughput will depend on things like the number and spin speed of the disks used, buffer sizes and so on. However, using the open source Iometer tool we recorded a throughput of 112MB/s on large sequential reads with an array of just three 1TB disks?close to the theoretical maximum for Gigabit Ethernet. Disk writes and random read/writes were somewhat slower, but when copying files and streaming video from the array we got figures close to those achieved when using direct attached storage.
Where does it disappoint?
A couple of issues surfaced while we were evaluating the DroboElite. The first is that it only supports iSCSI, whereas other vendors in the small business market offer dual-purpose storage devices that can be used both as NAS appliances and for iSCSI attachment.
Data Robotics does have a NAS appliance?the Drobo FS?but it’s a much smaller 5-disk product. The company also sells the DroboPro, based on the same 8-slot chassis as the DroboElite and, confusingly, able to be configured both as direct attached storage and as an iSCSI box, albeit with just one Gigabit interface and support for fewer virtual volumes. Which is all very well, but a little bit confusing given that most of the functionality is in the firmware so it ought to be possible to come up with a single multi-function solution.
Another option we’d like to see would be a built in backup facility, to enable data on the DroboElite array to be copied to another storage device, such as an external USB disk. That said, the DroboElite can be backed up just like any other SAN storage appliance, you just have to make separate arrangements to do so.
Would we recommend it?
The thing to remember about the DroboElite is that, although aimed at the small business, it’s not a NAS appliance?the most commonly sold of the SMB storage technologies. Indeed, if you’re expecting to be able to share files over the LAN, the DroboElite is not the product for you.
Rather it’s an IP SAN appliance, for companies looking to consolidate and centrally manage storage across one or more servers using iSCSI. For buyers who know that’s what they need then it’s a good product, especially where technical expertise is in short supply as it’s a good performer and about as easy to setup and manage as it’s possible to get.