TTI 2300 Series DLT backup system

Transitional Technology Inc’s Series 2300 DLT tape subsystem is one of the gems that I occasionally stumble across. While some administrators find tape backup units hard to get enthusiastic about I’ve lost many server drives over the years. A good set of tape backups are worth their weight in time and effort. TTI’s Series 2300 DLT subsystem just may become my standard tape unit, especially for critical information, after this review.

The Series 2300 is a separate box chassis, about ten inches high and wide, and slightly deeper. The back panel of our unit sported two 68-pin micro-D SCSI ports, an RS232 serial port connector, and a power switch. The front holds two complete DLT drives, each with an array of LEDs and status displays. It’s an impressive front panel to behold, especially for administrators used to older QIC and DAT drives. The entire unit can be rack mounted, if you want, although it stacks very nicely next to a server. The SCSI-based subsystem can be used with practically any SCSI-equipped operating system. We tested with SCO OpenServer 5 and UnixWare 7 servers, as well as Windows NT 4.0, HP HP-UX 10.2, and Solaris 2.7 servers all with equal success.

The magic of the Series 2300 is the DLT drives themselves. DLT (Digital Linear Tape) use half-inch tape cartridges that can hold up to 35GB uncompressed each, or double that compressed. The Series 2300 DLT drives use two read-write heads in each drive to provide high data transfer rates or 5MB/sec uncompressed, double that compressed. With two drives in the subsystem you can select to configure the drives with separate SCSI IDs or gang them together with a single ID. Mirroring is fully supported, as is cascading to the second drive when one tape is full. Mirroring is ideal for keeping one tape at the server location and an exact duplicate off-site. As a subsystem there are also some neat benefits, such as off-line copying and verification of tapes, which do not require server interaction.

The drive front panels include a set of lights for all drive operations, numerical displays of tape remaining and percentage rewrites (with error correction active), as well as two buttons to activate the menu for configuration. A set of alphabetic prompts on the panel step you through the configuration process for the drives and takes only a few minutes.

Little features abound and make the Series 2300 a winner. It can emulate over a dozen different tape drives, just in case your existing hardware and software wants a specific type. For example, you can easily configure the Series 2300 to behave like an Exabyte 8500 or 8505 drive for compatibility with backup software. The display of tape usage as well as the ECC scale shows tape quality and wear, letting you know when to replace a cartridge. When the tape drive heads need cleaning a "Time to Clean" message appears on the front-panel message screen. The menu system for configuration is easy to work with and quite a neat feature.

The Series 2300 can be purchased in a single DLT drive configuration, as well as with other tape drive units. However, as configured with two DLTs, the subsystem offers the greatest flexibility and convenience, especially for those administrators who need to regularly (and quickly) back up more than 25GB of data. On our test network we used the Series 2300 in place of an AIT drive for network-wide backups without a problem over the two week testing period. The ability to cascade to the second tape when the first is full helps not only for the full backup cycle, but also regular incremental backups (providing 140GB compressed across two cartridges, which sufficed for incrementals for over a week on our network). For those who need even more capacity, autoloaders and larger subsystems are all available.

Prompts on the front panels let you know exactly what the status of each tape cartridge is, much more conveniently than the rather boring front panels of AIT and DAT tape drives. We used the Series 2300 with standard tar and cpio commands, as well as with Cheyenne’s ArcServe backup software, all with no trouble. There is no software bundled with the Series 2300.

Once you’ve used DLT you’ll wonder why you bother with other tape systems. Loading and unloading the drives with cartridges is simple. The front panel display keeps you completely up to date. The drives are quiet. The backups are fast (my 60GB primary server backed up to a single cartridge in compressed mode in an hour and a half: AIC takes over two hours while DAT takes four hours) . While there are other high-capacity drives out there such as AIT and high-density DAT, I found the DLT subsystem faster and easier to work with than either of the others. The Series 2300 isn’t cheap, and DLT cartridges cost more than DAT tapes, but the speed and flexibility a subsystem like this offer make the cost easily justifiable for many servers. I’ve found my new backup subsystem!