tape drives

[Chuck Guzis]

> Date: Thu, 24 Apr 2008 14:20:17 -0400
> From: "Roy J. Tellason" 
 
> I saw some conversation going by in here recently about Exabyte drives, 
> only the numbers don't sound anything like what I have,  which is marked
> "Model: HH CTS".  There are all sorts of other numbers on there,  for
> various aspects of it.

Most Exabyte drives have model numbers of the form 8xxx, from 8000 to 
8900, then the "Mammoth" models.  The basic early 8200 will hold 
about 2.1G on a standard 8mm tape.  Later models require different 
tapes to take advantage of larger capacities.

Quality of the drives are all over the place, from the built-like-a-
brick-outhouse 8200 and 8500 to the cheap-hunk-of-plastic 8700.

> I'm told that these hold 20G on a tape.  The guy I got 'em from
> unfortunately doesn't have any tapes to go along with them.  One of those
> tapes would back up pretty much of what I have on my LAN here,  or whole
> machines,  as they sit.  I'm guessing that the interface I'll be looking
> at after I take it off of the current mounting plate will be SCSI-wide, 
> like the CD drives and some of the other stuff I have with it.

I suspect that that's 20G "compressed", which is the equivalent of 
"Chinese electric motor horsepower", i.e. extremely optimistic.

> Think I can get 'em going under linux?  :-)

Sure--just be certain that the SCSI "flavor" matches what you've got 
on your controller.  

The general idea is that any SCSI tape drive that supports the 
standard command set will work with Linux--and probably many other 
platforms.  It's been too long since I did "anybody's SCSI tape 
backup" software, but the only gotchas are packages that use 
nonstandard behavior such as read-after-write or strange varieities 
of tapemarks.  Heck, even the command set for auto-changers is 
standard, being applicable to a little magazine that sits in your 
tape drive to a bunch of robots crusing racks of 1/2" reel-to-reel 
tapes.  At least in theory, you can use anything from a 1/2" reel-to-
reel drive to a DLT without changing software.

Most SCSI tape drives feature read-after-write verification, which 
puts them way above the garden variety consumer "floppy tapes", most 
of which were garbage, IMOHO.

While not as good as DLT, 8mm is head-and-shoulders above 4mm DAT as 
concerns reliability.  The bottom of the barrel, IMOHO, was the 
Datasonix Pereos 2.5mm format.

Cheers,
Chuck