4 Aug
2015
4 Aug
'15
7:20 p.m.
On 08/04/2015 06:17 PM, jwsmobile wrote:
I was on the SCSI committee when the tape commands
were proposed. The
original that was proposed was to only have a commands which would be on
disk controllers (who were the main players) to perform backups of disk
units and restores. Luckily that effort was headed off by having
several parties who made tape devices other than Archive join the
committee.
I know the feeling from my short time with X3J3 (Fortran (was supposed
to be 88, but became 90)). The reps from DEC and IBM both threw a hissy
fit and threatened to withdraw if the committee didn't ratify their
particular extensions. It was not a nice experience.
It's really odd that the raw Pertec-style interface, even with its
various vendor extensions, is still more robust and versatile than the
SCSI version. On the other hand, the SCSI standard (X3T10?) does a
pretty good job of generalizing tape robots.
Amazingly I've never had a 4mm or 8mm tape fail to
read for media
reasons. I'm going on having media from both that are as old as the
technology. My 8mm backups have only one bad tape in the pile, and it
was marked as written "incomplete" and bad at the time of creation. Half
inch I've had the same problems documented with the quality of the
media, but it is much older.
Wasn't Exabyte the only vendor of 8mm tape backup? I've seen other
brands but they all seemed to have Exabyte internals. 4mm DLT is/was
remarkably robust, particularly when you consider the mechanical
intricacies. I was really surprised to see the medium extended to
DAT-320. Apparently, there's yet another generation in the works.
On the other hand, the consumer-level tape backups are really terrible;
Travan, DC-2100, etc. The worst of the bunch was the Datasonix Pereos
that used a (wait for it!) 2mm tiny tape cartridge that one had to order
from Datasonix via Fedex. Thankfully, that one was
brief.
--Chuck