Sidewinder 50

The Sidewinder 50 from Seagate Technology is a high-speed, high-capacity SCSI Advanced Intelligent Tape (AIT) backup unit that achieves impressive rates of data transfer. According to Seagate, the unit uses its 68-pin Fast/Wide SCSI-2 connection to achieve compressed-data transfer rates up to 6MBps and uncompressed-data transfer rates up to 3MBps.

The Sidewinder 50 saves to custom data cartridges, which are the same size as standard 8mm cartridges. Each cartridge contains a 16Kb EEPROM memory chip that facilitates quick positioning of the tape during restores by indexing the tape's data contents--a feature called Memory in Cassette (MIC) technology. Sidewinder 50 cartridges use a media known as Advanced Metal Evaporated (AME) tape, which has unique recording characteristics that yield higher performance than standard backup tapes with fewer data dropouts. Each Sidewinder 50 data cartridge has a native capacity of 25GB of uncompressed data. Using adaptive lossless data compression, the unit can achieve a backup capacity of 50GB per cartridge.

The Sidewinder 50 unit is small enough to install in place of two 3.5" disk drives in a typical tower system. My test unit arrived with mounting rails and without an external cabinet. It was a typical unit ready for installation in a half-height 5.25" drive bay. Rather than disassembling my server to install the unit internally, I set up my Sidewinder 50 in an external Fast/Wide SCSI enclosure. I didn't need to prep the unit at all--jumpers let you select a SCSI ID and firmware, but I stuck with the default settings for my testing.

After installing the Sidewinder 50 in the external drive enclosure, I used an external SCSI connection to attach the unit to my Digital Prioris HX-590 Windows NT server. This system has dual 90MHz Pentium processors, 96MB of RAM, and a DAC960 RAID-5 controller. I rebooted the Prioris and made some minor adjustments to my configuration of Computer Associates' ARCserve, which I use to back up my system. I then began using the Sidewinder 50.

The Sidewinder 50's tape load time surprised me. I can stick a tape in my Exabyte 8700 8mm tape drive and get myself a cup of coffee during the time the unit takes to load. The Sidewinder 50 takes only 6 seconds to load a tape. The Sidewinder 50 ejects tapes without rewinding them, which saves time during backups but can be problematic when you try to access saved information. The unit also has a self-cleaning feature, which saves you from keeping track of cleaning dates or having backups fail because of dirty heads. Seagate reports a mean time between failures (MTBF) of 200,000 hours for the unit.

Despite my enthusiasm over the Sidewinder 50's quick load and eject times, I found the unit's data transfer speed a little disappointing. The Sidewinder 50's published specifications clock its uncompressed-data transfer at 3MBps, or 180MB per minute. However, in my tests, the Sidewinder 50 took 15 minutes to perform a full backup of a 1.2GB file system--a transfer rate of roughly 80MB per minute. The unit's Fast/Wide SCSI-2 interface did not live up to my expectations.

To take maximum advantage of MIC technology, you must use MIC-aware backup software. For example, to retrieve information about a tape's data structure and history, your backup software must specifically instruct the Sidewinder 50 to retrieve this data from the cartridge's EEPROM memory chip. My ARCserve software is not MIC-aware, and I do not know of any backup-software vendors that currently support this new technology.

However, I recommend the Sidewinder 50 for high-volume backups. The 80MB-per-minute transfer rate I achieved beats the speeds of competing tape systems, and I expect vendors to soon produce MIC-compatible software. If you need a large-capacity tape backup system, add the Sidewinder 50 to your short list.

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