Drobo is a family of external storage devices for computers. They are made in a variety of types including DAS, SAN, and NAS appliances made by Drobo, Inc. Drobo devices can house up to four, five, eight, or twelve 3.5" Serial ATA or Serial Attached SCSI hard disk drives and connect with a computer or network via USB 2.0, USB 3.0, FireWire 800, eSATA, or Gigabit Ethernet. Drobo devices are primarily designed to allow installation and removal of hard disk drives without requiring manual data migration, and also for increasing storage capacity of the unit without downtime.

Products [link]

Overview [link]

2nd Generation [link]

In July 2008, Drobo announced a 2nd generation model ^[1][2] , which offered a faster core processor, optimized firmware, better USB 2.0 performance and a pair of FireWire 800 ports, which are compatible with FireWire 400-to-800 cables and adapters.

Firmware is available to support drives in excess of 3TB (firmware v1.4.0.).^[3][4]

Technical Specifications [link]

• Marvell 500 MHz System-on-a-chip (SOC) processor (Marvell 88F5281-D0)
  • Includes support for PCI-X, PCI Express, Gigabit Ethernet, USB 2.0, DDR2 32bit 200mhz
  • Based on Marvell Feroceon RISC core (ARMv5TE)
  • Same processor used in the Apple Time Capsule and in several other NAS devices
• Marvell PCI-X 4-Port SATA-II Controller (Marvell 88SX6042-BCZ1)
• 1 GB RAM (2x Hynix H5PS5162FFR 512Mb DDR2 SDRAM 2-5-5-5)
• 128 Mb NOR flash memory (Spansion GL128P90FFIR2 90 nm, 25ns page access, 90ns random access)
• 64 Macrocell PLD (Programmable Logic Device - XILINX XC2C64A
• 3 Port Firewire 800 (1394b) controller (TI XIO2213AZAY - PCI Express)
• 45 mAh Manganese rechargeable lithium NVRAM battery (ML2020 - 3V)
• DC cooling fan (2-wire brushless)

DroboPro [link]

In early 2009, Drobo announced a new model called the DroboPro which is physically larger than the Drobo and offers the option of being mounted in a 19-inch rack. The DroboPro has the increased capacity of 8 drive bays rather than 4 in the original model, giving a 16 TB theoretical maximum with the current 2 TB drives. It also adds "Dual Disk Redundancy" akin to RAID 6. iSCSI via Gigabit Ethernet has been added alongside existing USB and FireWire 800/400 interfaces. However, the iSCSI implementation currently only supports connection to a single server^[5] and unlike the Drobo FS, the Ethernet interface cannot be used for other networking protocols such as NFS, FTP, or SMB.

DroboElite [link]

On 23 November 2009, Drobo added a new model to its product line, called DroboElite. Its main difference versus the DroboPro is that it allows simultaneous access for up to 16 hosts, via two iSCSI ports. The Elite version also supports up to 255 volumes (vs. 16 in the Pro version).^[6]

Drobo FS [link]

Drobo FS launched at Tech Field Day in May 2010.^[7] The key difference with the 'S' models as well as the 'first' and 'second' generation models is the LAN port i.e. Ethernet RJ45 (without the requirement of a Drobo network interface).
5 HDD slots available.

It provides up to 10.89TB of storage when using 5 HDDs of 3TB. This is less than the sum of the drives because of fault tolerance.

Dual disk redundancy will reduce the possible storage capacity to 8.17TB.

Larger capacity drives greater than 4TB are automatically supported as they become available..^[8]

Specifications [link]

Processor : ARM926EJ-S rev 0 (v5l) MemTotal  : 189028 kB

Software [link]

Kernel  :Linux Drobo-FS 2.6.22.18

BusyBox v1.14.2 (2009-07-29 17:47:47 PDT) multi-call binary

Current DroboApps on the official website:

Perl is the underlying programming language for the DroboApps.

All apps are specific for each type of Drobo.

Features [link]

• Data protection for all drives, as Drobo controls any access to the data.
• Recognizes and utilizes newly added storage devices on the fly.
• Hard drives do not need to be matched in terms of capacity, speed, or manufacturer.
• The drives appear as one unified drive to the host operating system without requiring the installation of the management software on the host.
• Supported file systems: HFS Plus, NTFS, ext3 and FAT32
• File system redundancy is managed by a virtualization layer which lays data out in a proprietary Drobo format.
• Second FireWire port allows a user to daisy-chain multiple Drobos up to a computer. Each Drobo mounts as a separate system on the computer.
• With the addition of the Drobo FS network-attached storage (NAS) add-on, functionality can be added via open-source software. Examples are iTunes music server functionality, UPnP/DLNA support, and FTP access.

BeyondRAID [link]

Drobo, Inc. implements a storage technology that they call BeyondRAID in their Drobo storage devices. While not a true RAID ISO spec extension, it does provide for using up to 12 SATA hard drives in the devices and consolidating them into one big pool of storage. It has the advantage of being able to use multiple disk sizes at once, much like a JBOD unit, while providing redundancy for all disks and allowing a hot-swap upgrade at any time. Internally it uses a mix of techniques similar to RAID 1 and RAID 5. Depending on the amount of data stored on the unit in relation to the installed capacity, it may be able to survive up to 3 drive failures, if the "array" can be restored onto the remaining good disks before another drive fails. The amount of usable storage in a Drobo unit can be approximated by adding up the capacities of all the disks and subtracting the capacity of the largest disk. For example, if a 500, 400, 200, and 100 GB drive were installed, the approximate usable capacity would be 500+400+200+100-(500)=700 GB of usable space. Internally the data would be distributed in two RAID 5-like arrays and one RAID 1-like set:

           Drives
 | 100 GB | 200 GB | 400 GB | 500 GB |

                            ----------
                            |   x    | unusable space (100 GB)
                            ----------
                   -------------------
                   |   A1   |   A1   | RAID 1 set (2× 100 GB)
                   -------------------
                   -------------------
                   |   B1   |   B1   | RAID 1 set (2× 100 GB)
                   -------------------
          ----------------------------
          |   C1   |   C2   |   Cp   | RAID 5 array (3× 100 GB)
          ----------------------------
 -------------------------------------
 |   D1   |   D2   |   D3   |   Dp   | RAID 5 array (4× 100 GB)
 -------------------------------------

With the introduction of the DroboPro, a RAID6 like feature was also introduced. BeyondRAID also has the ability to perform hash-based compression using 160-bit SHA1 hashes to maximize storage efficiency.

Detailed technical information about BeyondRAID, including how it handles adding and removing drives, can be found in the patent application at the US Patent Office, US Patent Application No. 20070266037 .

Criticism [link]

The Drobo was initially criticized for lacking an Ethernet port,^[9] preventing it from being used as a self-contained NAS appliance. These complaints have been addressed with the release of the DroboShare physical add-on, and the release of the Drobo FS and DroboPro FS, dedicated NAS versions.

Some reviewers complained about speed and reliability issues of the 2nd generation Drobo when connected to a Windows PC using FireWire 800.^[10]

Competitors and Alternatives [link]

Other companies, for example Netgear, Seagate, and Synology, offer similar virtualised redundancy features under different brand names^[11]. Microsoft Windows 8 will include similar functionality built-in with Storage Spaces.

References [link]

External links [link]

• Official website
• Information regarding HD video editing in relation to the Drobo product range

Reviews [link]

• PC Perspective DroboPro in-depth review
• Drobo FS Unboxing and Review
• DroboElite Review