A while back I asked:
]Subject: exabyte data compression module
]
]We've outgrown the capacity of our Exabyte 8200...
]
]Anybody have any experience with one of those hardware data compression
]modules that plug into an Exabyte 8mm tape drive? Are you happy with it?
]Where did you get it? How much did it cost? Is it completely transparent
]to the Sun SCSI driver? How difficult was it to install?
]
]
]--
]Todd Pfaff \ Internet: todd@flex.eng.mcmaster.ca
]Dept. of Mechanical Engineering \ Voice: (416) 525-9140 x2902
]McMaster University \ FAX: (416) 572-7944
]Hamilton, Ontario, CANADA L8S 4L7 \
I got lots of "me too!" responses asking for a summary, so here it is.
It was pointed out that the Sun SCSI drivers don't support the compression
modules. I previously thought that such a module was transparent to the
driver and no software was required. Anybody know more about this?
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From: jpl@allegra.att.com (John P. Linderman)
We have an Exabyte 8500. 4.4 gig on the same Sony P6120MP tapes
you've come to know and love. 5.5 gig (we hear) on Sony QG122M
tapes. Worked on the SparcStation 2 fresh out of the box...
no driver mods, (but make sure you get one with curent firmware...
no earlier than 3F2.)
My thinking is this. 8500's are likely to become as common as
8200's, cause they don't cost much more, but hold much more.
They can read back 8200 tapes. If I go with some fancy
compression scheme, I'll need the decompression scheme on the
way out. Right now, that isn't as readily available as 8500's.
So I'll rely on standard technology rather than proprietary
coding schemes to kee apace with growing disk capacities.
And sleep well about restoring my tapes anywhere I want.
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From: Mike.McCann@eng.clemson.edu (Mike McCann)
I just recently installed a TR-1 compression module and data panel on my 8mm drive.
It seems to work just fine and has more than doubled the capcity of my tapes.
TR-1 Data Compression Module
Peripheral Vision Corp.
712 Paseo del Ray Playa del Rey, Calif 90293
(213) 574-1144 FAX: (213) 574-1141
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From: eric@mpl.UCSD.EDU (Eric Wolin)
I would suggest a 8500 instead as they work quite well and
are guaranteed to have 2x the capacity/transfer rate. You
can get an idea of how well things compress by using the
compress utility on some sample files you are backing up
as it uses the Ziv-Lempel algorithm which is supposedly
what most hardware data compression schemes use. For data
that uses the dynamic range we only saw a ~20% compression
improvement while you get 100% + from character (ASCII) data
files. As we have mostly data files we didn't bother with
purchasing compression units. 8500s are ~$2500.
Short term forecasts are that the helical scan drives (dat,Exabyte)
will improve by ~2x/ yr. (capacity & transfer rate) for at least
a couple of cycles.
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From: tonyr@tekadg.adg.tek.com
I got one for my 8200 drive. It installs very easily. I got it from
APUNIX for $754 plus $25 for software, which includes a driver. The Sun
SCSI driver will still write to the drive but can't take advantage of
the compression stuff. The module itself is made by Peripheral Visions;
APUNIX adds some software and sells it to you. It works as advertised.
I've had no problems. I guess you could say I'm a satisfied customer.
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From: tony@apldss.apl.cul.ca (Tony Schiebel)
We currently have an Exabyte 8500 8mm tape drive with the Extrabyte compression
module on it. It ran great on our sun 4/490 under 4.1 but now that we have
upgraded to 4.1.1, the standard Sun drivers do not recogize the full 5 GB +
compression. We are only getting 2.3 GB backups. Yay !!! :-) I am in the
process of hunting down some third party backup tools that will contain the
drivers we need. The SUN Techie says that they will offer support for the
5 GB drive in the first quarter of 1992.
We have had absolutly no problems with the compression module. It just plugs
right in and away you go. It cost ~1800.00 CAN. and was purchased from a
company called Enhance Sytstems. Like I said, It works great under 4.1 so
beware if you plan on running 4.1.1.
If you have any more questions, send me some e-mail and I will be happy to
help you.
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From: mks!andy@watmath.uwaterloo.ca (Andy Toy)
Please summarise. I am considering adding compression to my 8200. My
Contemporary Cyberbnetics Group CY-8200 can be upgraded with compression
from CCG for about US$2000 by shipping it to them. They have their own
compression upgrade. I have also found two third party compression
modules for the Exabyte. They are field installable so I would not lose
my drive for any significant period of time. Both modules are from
companies in California and cost about US$1000. I don't have the names
handy, but I will look them up for you if you like. Of course, they are
not compatible with each other so you can only exchange tapes with other
Exabytes having the same compression module.
Exabyte has announced 8200 and 8500 drives with compression. Both are
to be released within a year. The 8500 compression model first in a
couple of months. I believe these will become the defacto standard for
compression so I am recommending that we either wait for these drives or
just buy another 8200 or 8500 instead of the add-on compression module.
I don't want to have tapes that are only readable by my drives.
However, if money is tight then we may go with a third party compression
scheme.
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From: mks!andy@watmath.uwaterloo.ca (Andy Toy)
One of the compression modules for the Exabyte is from Peripheral Vision
Corp. 7712 Paeo del Rey, Playa del Rey, CA, USA, 213-574-1144, fax
213-574-1141. The product is available in Canada from Dilog Canada,
4 Paget Road, Brampton, L6T 5G3, 416-790-0660, fax 416-790-0712.
The other is from Digi-Data Corp., 8580 Dorsey Run Road, Jessup, MD, USA,
301-498-0200, fax 301-498-0771, 800-782-6395.
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-- Todd Pfaff \ Internet: todd@flex.eng.mcmaster.ca Dept. of Mechanical Engineering \ Voice: (416) 525-9140 x2902 McMaster University \ FAX: (416) 572-7944 Hamilton, Ontario, CANADA L8S 4L7 \
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