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Exabyte and Mammoth Technology

exabyte-and-tape

Exabyte Drive and Media

Exabyte Corporation pioneered the use of helical scan technology for data backup. The first Exabyte drive (Exabyte 8200) was introduced in 1987 as was basically a SONY camcorder with a SCSI interface, but importantly it left all other tape devices behind in terms of capacity allowing 2GB to be written to an 8mm tape.

The drive gained quick recognition and was adopted in the AS400, UNIX and VAX markets by people who would at last be able to kick off a backup and go home rather than waiting to change tapes a few times during the evening.

The 8200 was followed by the 8500 drive which incorporated improvements in the head technology and interface, but was still a full height drive. There were many add on companies who produced compression boards and jazzy LCD interfaces for the Exabyte range of drives so as to sell them for a good mark-up into the computer world. The Exabyte 8500C was introduced in the early 1990s, this was the 8500 but with the additional of data compression.

In the mid-1990s Exabyte moved away from the SONY full height mechanisms and adopted newer have height ones for the 8205 and 8505 drives. these drives had a soft load mechanism rather than the rather clunky door loader that was not practical for auto loading devices. the 8505XL took advantage of extra length tapes to give 7GB (14GB if compressed), and the 8700 was basically the 8505XL with some tweaks.

There was a quantum shift in the middle of the 1990s with the Mammoth drive (I believe it was based upon a Grundig mechanism) which used new higher density media (AME - Advanced Metal Evaporated) and tool the storage capacity up to 20GB. the drive could read tapes from the 8505 and 8700 drives, but it was not a good idea as you then had to run a cleaning tape through the drive before you could load an AME tape.

In 1999 the Mammoth2 drive was introduced, this was the last drive in the range. Ecrix, a break away from Exabyte, had developed the VXA 8mm drive and in 2001 were purchased by Exabyte to expand their range. Exabyte were subsequently purchased by Tandberg in 2006 and the VXA drive is continuing for now, but the Mammoth is a thing of the past.

How Exabyte Recording Works

Exabyte drives uses helical scan recording method similar to DAT and AIT (as opposed to the serpentine or linear method of recording employed by DLT and LTO technology). The recording media is 8mm wide.

helical-scan-recording

Above: Helical scan recording


With helical scan recording, data is written to a relatively slow moving tape via a fast spinning read/write head drum. This technology has the reported benefit of greater head durability, and reduced shoe-shining effect, the to and fro-ing tape motion that can occur in linear recoding if data is not slower than the recoding speed.

The external properties of a 8mm Exabyte are 95mm x 63mm x 15mm (L x W x D) and uses a cassette type format where the source and take-up spool are housed within the cassette.

Exabyte & Mammoth Drive and Tape Capacities

Drive Native Capacity Data Rate (MB/s) Year Tape Type Tape Length
Data Compression
EXB-8200 2.4GB 0.246 1987 MP 112m No
EXB-8500 5GB 0.500 1990 MP 112m Yes (8500C)
EXB-8505XL 7GB 0.500 1994 MP 160m Yes
EXB-8900
(mammoth)
20 GB 3 1996 AME 170m Yes
Mammoth-2 60GB 12 1999 AME 225m Yes

Exabyte Tape Data Recovery

The most common requirements for tape data recovery from 8mm media relate to mechanical wear resulting in mis-tracked or otherwise out of specification recordings. Helical scan mechanisms hold the tape in a fixed position relative to the head assembly by means of a sequence of rollers and when these become loosened the result is that the tape is mis-positioned and the recording drifts outside of normal tolerances. At some point the drive gives up completely and is replaced, the new drive will not recognise the data on the tape and data recovery is required.

Data recovery can also be required following accidental overwriting, physical tape damage, and media flaws. Fortunately, as with VXA, the 8mm tape is robust and it is usually possible to make a substantial recovery even when the problems appear severe.

Last Updated (Tuesday, 23 June 2009 17:14)

 
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