SAN MATEO (05/08/2000) - Using a server-dedicated tape library is a good idea for many reasons, among them security, portability, convenience, and capacity, but we usually avoid specifying such devices because of the cost. Certain power-desktop applications, including scientific, analytical, financial, and digital media, consume massive amounts of disk space. Unattended backup strategies won't fly because no single tape drive can absorb enough data. That workstation's user must sit through every backup operation and manually change tapes. Shipping huge files through your LAN for centralized backup eats bandwidth and is a drain on shared media. Many systems need dedicated backup devices, yet all of our choices are either too small or too expensive.
Thanks to Benchmark Tape Systems Corp., we now have a solution that fits many technical requirements and most budgets. Benchmark DLT7 is a seven-cartridge DLT (digital linear tape) autoloader with a native (uncompressed) capacity of 280GB. Its robotic picker feeds cartridges into a Benchmark DLT1 40/80 (native/compressed) tape drive. What makes the seemingly unremarkable DLT7 worth notice is its price. Adic FastStor, the very chassis used to make the DLT7, is equipped with a Quantum DLT8000 drive for about $8,800. The list price for Benchmark DLT7 -- same box, same mechanism, same capacity -- is $4,779.
That's almost identical to the street price for an external Quantum DLT8000, a popular stand-alone backup drive. For the same money, the DLT7 gives you seven times the capacity as the DLT8000. This isn't one of those "too good to be true" deals. As long as you're careful to place the DLT7 in a role that suits it, you can't beat it. For those circumstances, I give the Benchmark DLT7 a Very Good score.
It had better be easy
The only way backup gets done is when it's painless. An autoloader eases the pain of manual cartridge changes, but it can present its own headaches. Breathe easy; the DLT7 couldn't be easier to deploy. It weighs 26 pounds and lives in a 7.5-by-9.5-by-23-inch cabinet. The DLT7 fits on a desk or on top of a tower system chassis.
Benchmark ships the DLT7 ready to run: A well-made, 6-foot-long, 68-pin cable and an auto-sensing active terminator are in the box. For a few bucks more, the box can also contain one DLT IV tape. I connected the library to a PC server with an 850MHz AMD Athlon CPU and 384MB of RAM. I used Microsoft Windows 2000 Advanced Server and Veritas Backup Exec 8 to test the device. (A review of Backup Exec starts on page 67.) I tested with both Ultra Wide and Ultra2 LVD (low voltage differential) Adaptec SCSI controllers. The DLT7 and the active terminator sensed the interface type and adjusted automatically. I used a Consensys RAIDZone disk array packed with 162GB of storage to give the DLT7 something to back up.
To avoid having to provide specialized device drivers, Benchmark made its device protocol-compatible with Quantum DLT drives. The DLT1 even tells your system it's a Quantum DLT7000. Windows 2000 and Backup Exec are happy with this subterfuge. All drive operations go through Quantum DLT device drivers. I tested the drivers included with Windows 2000 and the replacements installed by Veritas with nary a hitch.
A tape library's loader mechanism communicates with your SCSI controller as an independent SCSI device. Wisely, Benchmark chose not to rebrand the Adic loader's device string. The DLT7 tells the system it's an Adic autoloader.
Backup Exec 8's configuration of the device was automatic. After cutting the packing tape, I was ready to burn my first backups in fewer than 10 minutes.
When seven equals five
The DLT7 claims seven cartridge slots, but that's a trifle misleading. Five of the slots are right behind the hinged door. There is no removable magazine; you load the five front-facing slots individually. The other two slots are hidden in the back behind the picker robot. You can reach through the loader to push tapes into these slots, but I don't advise it. The DLT7 has no safety features.
You can open the door and stick your hand inside the unit while the picker is in motion. For safety's sake, use the front panel menu to shuttle tapes from the external slots to the internal ones.
The DLT7 lacks a standard bar-code reader. To inventory the slots at start-up, Backup Exec must ferry every cartridge to the drive and read its header. That's a lengthy process that is repeated every time you restart. Benchmark doesn't offer a bar code add-on, but Adic does. The attachment costs about $600, and the DLT7 includes the needed connector. I strongly recommend attaching the reader if you plan to change media often.
The front panel display is small, but brightly lit and easy to read. Menu buttons sit behind the door. There isn't much to the menu, so it's easy to navigate. You can load and unload the drive manually, transferring media from or to any slot. The menu will also move cartridges to the rear slots and reassign the device's SCSI IDs. When a slot is occupied, a block appears in the display. After the loader moves a cartridge to the drive, its original slot number is shown in large type. The current operation, such as read, write, rewind, is spelled out as commands come in. The front panel is adequate, but it lacks some features such as password security and off-line diagnostics.
Performance and compatibility
The loader mechanism of the DLT7 turns in an average performance. It takes about 22 seconds to move a cartridge from a slot to the drive. Loading and calibration takes roughly a minute, a time on par with other DLT drives.
Unloading is quick: It takes about 45 seconds to unthread, eject, and return a cartridge to its slot.
The DLT7's data throughput is determined solely by the DLT1 drive. At a native rate of 3MB per second (confirmed by my tests), the DLT7 lags behind Quantum's DLT8000, which streams in my lab at 5MB to 6MB per second. These speeds roughly double when you archive readily-compressible data. The DLT1 lacks Quantum's variable-speed technology. As a result, Benchmark's DLT1 takes much longer to locate individual files. But consider that we're comparing Quantum's top-of-the-line $5,000 DLT drive to one for $1,500.
I wouldn't use the DLT7 in a demanding production environment such as a busy server room. The DLT7 has no magazine, no software-operated door lock to prevent accidents and post-inventory media changes, and a few too many plastic parts to qualify for the raised floor of the server room. But then, its capacity alone is enough to count it out for serious server use. Yet the DLT7 is a perfect fit wherever you would otherwise use a single tape drive.
The DLT1 drive uses standard DLT IV cartridges and will read tapes recorded on a Quantum DLT4000. Beyond that, a DLT1 will exchange media only with other DLT1s. Outside your central battery of tape libraries, compatibility is no issue. You're not likely to move a tape from a desktop DLT7 to one of your raised-floor autoloaders.
When weighing its strengths and shortcomings, it's important to see the DLT7 for what it is: a $5,000 desktop tape library. Examined in that light, the DLT7 fairly sparkles. Its 280GB capacity is a perfect fit for non-production servers and power desktops. It is small and light enough to be portable or even to be locked in a cabinet at night.
No device in its price range can match the DLT7's capacity and features. The next time you get ready to spend $5,000 on a tape drive, consider buying a DLT7 instead. I rate it Very Good.
You can reach senior analyst Tom Yager at firstname.lastname@example.org.
THE BOTTOM LINE: VERY GOOD
Benchmark Tape Systems DLT7
Business Case: The DLT7 seven-cartridge desktop tape library packs a lot of backup capacity (280GB uncompressed) into a small space. Its price is comparable to Quantum's DLT8000 stand-alone DLT drive, making the DLT7 worth considering.
Technology Case: The DLT7 uses Benchmark Tape Systems' low-cost DLT1 tape drive. Despite fixed slots and DLT media incompatibility, the DLT7 works well and is too good a value to pass up. Just take care to match its duties to its strengths.
+ Extremely affordable
+ Uses popular DLT IV tapes
+ Light and portable
- Limited compatibility with other DLT drives (reads DLT4000 media)- Lacks safety featuresCost: $4,779.
Platform(s): Systems equipped with wide or LVD SCSI interfaces.
Benchmark Tape Systems Corp., Boulder, Colorado; (303) 443-7358; www.benchmarktape.com