Tape backup is not perfect: even if your backup process works as it is intended to, there is the possibility of the drive failing to write correctly. Worse, it might appear to write correctly, but at restore time the media turns out to be damaged or otherwise unreadable.
DLTSage is Quantum's attempt to solve this problem via predictive and preventative maintenance. It combines diagnostic firmware within the tape drive with application software - either Quantum's own diagnostic software or a suitably adapted backup program.
The need for it is clear - where only four years ago a tape cartridge held 40GB, now it is nearly 1TB, which is a lot of data to entrust to a length of metallised polymer. It is driven by changed usage patterns too: the trend towards using tape for archive rather than backup, as disk takes on the latter role, means you have to be absolutely sure when you write data that it is correct.
The first part of DLTSage is firmware to generate system status and tape events. This capability is built into new Quantum drives from the SDLT-600 onwards, and available for the earlier SDLT-220 and 320 via a firmware upgrade. The firmware determines the breadth of problems that can be reported on, so it is a design issue for the manufacturer.
You then get to that data via the SCSI interface on the back of the drive and host-based diagnostic software, or via an infrared port on the front of newer tape drives. The IR port bypasses SCSI to give access to the base-level data - the original information reported by the firmware - while the drive uses this same information to send tape alerts to the backup software via SCSI.
IR connectivity also makes it possible for technicians to interrogate a drive's status and health on-site, without having to remove it from the library or rely on the LAN for connectivity. Quantum provides a client program called iTalk which can be run from the command line on a PC or on a Microsoft PocketPC - PDAs almost all have IR, making them useful for portable diagnostics.
For most users though, the real value is likely to come from an ISV application that uses the DLTSage data for predictive reporting. For example, if there is a temperature issue or there are write errors, the drive can send an alert before it becomes a problem.
DLTSage is Quantum's implementation of the MAM (media auxiliary memory) standard from the T10 committee responsible for SCSI, which provides a series of outputs which the software application interprets. Its advantage over earlier MAM implementations is that it reads and captures more error data, allowing it to make better predictions of a drive's vulnerability to failure
For example, it can build up an inventory of drives and media with usage statistics. That means you can ensure that the workload is evenly spread over the available drives, watch error trends, and see where those errors are happening.
Over time, this kind of intelligent predictive and preventative maintenance will spread to other tape drive formats - Quantum's takeover of Certance brings DLTSage and LTO technologies together in one company, for example, while other tape developers are likely to come up with equivalents of their own. In the meantime, innovative tape management via DLTSage is one of SuperDLT's strongest selling points.
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