Volume Number: 22 (2006)
Issue Number: 2
Column Tag: Review

Quantum's SDLT 600 Tape Drive System

by MacTech Staff

Quantum is in an interesting position in the market, in that they are leaders with both their DLT and LTO technologies. Both of these technologies are great, and have multiple sources for media. The first priority for DLT is capacity, and the first priority for LTO is speed. That said, LTO's capacity is terrific, and DLT's speed is no slouch either. To be fair, DTL was invented by Quantum. LTO, on the other hand, was invented by IBM. Quantum acquired Certance a while back which gave them a firm foothold in the LTO market, allowing Quantum to give their customers a wider array of choices.

For MacTech, capacity was the highest priority, so we went the DLT direction. There are several different levels of DLT from the most economical to the highest capacity. The latest in the DLT family is the DLT-S4 which holds a whopping 1.6 terabytes per cartridge (compressed) which is twice the capacity of the LTO-3 standard, and nearly three times the SDLT 600 that we selected for this review.

Whether you choose DLT or LTO, there are a variety of auto loader and library solutions for you to choose from. It's all a matter of budget, and how much you need to back up. Both have road maps for the future. DLT is on path to ultimately get to 14 terabytes per cartridge.

The bottom line is that no matter what you decide, DLT or LTO, you are bound to be pleased. Both are great technologies, with great brands behind them, lots of tape vendors, and are speedy with high capacity.

SDLT 600 tape drive systems are at the upper end of Quantum's line of digital linear tape drives that include the SDLT 220, SDLT 320, and of course, the new DLT-S4. The SDLT 600 tape drive system comprises both the tape drive and the data cartridge. The tape system is available in four versions, an internal unit for server installation, a tabletop unit, a rack mount, and a library model for installing in tape automation systems. The tape drive provides 300 GB of storage capacity with a transfer speed of 36 MB/sec in native mode, and 600 GB of storage capacity with a transfer speed of 72 MB/sec in compressed mode. MacTech has regularly been able to get 450 GB out of tapes in real world usage.

SDLT 600 contains on-board hardware to compress and decompress data using a DLZ algorithm. The default setting for data compression is on. This system utilizes DLTSage, a data management solution that allows users to manage, predict and prevent problems before they occur. It also comes with DLTIce, which provides WORM (Write Once, Read Many) archival functionality, although we did not experiment with this.

For those that care about the nitty gritty details, SDLT 600 has 40 logical and 640 physical tracks with a track density of 1502 tracks per inch (tpi). Linear bit density is 233 Kbits per inch (Kbpi) with read/write tape speed of 108 inches per second (ips), rewind tape Speed of 160 ips, and linear search tape speed of 160 ips. The average rewind time, maximum rewind time, average access time (from beginning of tape), and maximum access time (from beginning of tape) are 77, 156 seconds, 79, and 190 seconds respectively. The typical load from the beginning of tape time and unload to beginning of tape time are 18 and 19 seconds respectively, while load to beginning of tape for unformatted tape takes 63 seconds. Nominal tape tension is 3.0 +/- 0.5 oz for stationary drive, and 3.5 +/- 0.5 oz at operating speed.

SDLT 600 is a streaming tape drive that uses half-inch wide Super Digital Linear Tape (MR-S2MQN-01) media and offers backward read compatibility with the SDLT 220 and SDLT 320 tape drive formats, Super DLTtape I data cartridge type, and the DLT VS160 tape drive format with DLTtape VS1 data cartridge type. It does not, however, have the ability to use the older DLT tapes that look like they would fit, but don't. Definitely do not try this: you'll damage the drive.

This tape drive utilizes the SDLT Cleaning (MR-SACCL-01) cartridge. But, don't go out and buy a ton of these ... they work for 25 cleanings, and you should not clean proactively, only when the drive asks for it (through the indicator light or software). After months of using this drive for every day backups, we've yet to clean it.

This product is powered by Quantum's Laser Guided Magnetic Recording (LGMR) technology that provides a combination of the optical and magnetic technologies, resulting in higher capacities by substantially increasing the number of recording tracks on the data-bearing surface of the media. It is equipped with Pivoting Optical Servo (POS), a Quantum-invented, optically-encoded servo system, that combines high-density magnetic read/write data recording with laser servo guiding. The system also features Magneto Resistive Cluster (MRC) heads, advanced Partial Response Maximum Likelihood technology, Advanced Metal Powder (AMP) media, and positive engagement tape leader buckling mechanism.

SDLT 600 also comes with the TapeAlert feature that enables constant monitoring of the device's hardware and media for errors and potential difficulties by an internal SDLT firmware. It flags any problems identified on the SCSI log page, where 64 bytes are reserved for TapeAlert.

This tape drive is available with either Ultra 160 SCSI or Fibre Channel interfaces. The Ultra 160 SCSI interface provides a low-voltage differential (LVD) mode running up to 160 MB/second and a single-ended (SE) mode running up to 40 MB/sec. Fibre Channel interface runs at speeds up to either 1 Gb/sec or 2 Gb/sec, depending on the configuration chosen during installation. Fibre Channel can support up to 126 devices in a loop configuration. Long wave transceivers (with fiber optic cable) support distances up to 10 Kilometers, and the shortwave transceivers (with fiber optic cable) support distances up to 500 meters.

We tested the Ultra 160 SCSI version in our installation.

The projected MTBF (mean time between failures) for SDLT 600 is 250,000 hours. Head life is a minimum of 30,000 tape motion hours, and an average of 50,000 media motion hours. In terms of media durability, the number of media passes and full media uses to expect from a Super DLTtape II data cartridge are 1,000,000 and 250 respectively. In terms of data cartridge life expectancy, the number of load/unload cycles and media insertions to expect before the data cartridges need to be replaced are 5,000 and 20,000 respectively. The positive engagement tape leader buckling mechanism engages the tape leaders upon data cartridge load, and disengages them upon data cartridge unload. This allows buckle arm components including take-up leader, supply leader, and the media to function for at least 250,000 cycles on an SDLT 600 tape drive without failure, breakage, or binding.

This product was simply a pleasure to review, and to have in our network. It's must be part Macintosh, as from day one, we plugged it in, and it just worked. Two thumbs up!

We found an assortment of online resellers for the two tape drives with prices as low as:

Quantum SDLT 600 Internal: $ 2,899

Quantum SDLT 600 External: $ 3,099

For more information visit: http://www.quantum.com

MacTech Staff