#SCSI TAPE HELP
11 messages in this thread
Dom,
It's called a 125 Meg drive because that's what the manufacturer
calls it. I presume it's because that's how much information can be put on
a standard DC600 tape. Longer tapes would provide more, shorter tapes
would provide less.
I have no idea what the differences might be between your 5150 and
my 5125, but I suspect it's because mine was built to AT&T's specifications
and yours was built to "generic" specifications.
I believe TTR is (well…"was") full of stuff. To the best of my
knowledge, the difference between a 6150 tape and a 6250 tape is the
formulation of the magnetic media…not the length of the tape. There are
no patterns to be "set" in the head other than wear patterns. I am NOT an
expert on the differences between the tapes or the drives for that fact.
So I could be full of stuff.
If you don't have terminator power on a SCSI bus…it doesn't work
very well, if at all. The signal lines on a SCSI bus are binary..that is,
either ON or OFF. An ON condition is set when the signal line is at 0
volts. An OFF condition is set when the voltage is above 2.5 volts. The
OFF condition is set by dropping the terminator power line between a 220
ohm resistor to the signal line and then to a 330 ohm resistor to ground.
The ON condition is set when the signal line "sinks" that voltage between
the 2 resistors to 0 volts.
5v terminator power—————+
220 ohm resistor—————–>|
signal line———————–+
330 ohm resistor—————–>|
signal ground line—————-+
Without terminator power…the signal lines are 0 v (ON) at all
times.
Don
Don,
Thanks for all that info on tapes and terminator power.
Do you think there would be any harm in trying a longer tape with my
tape drive?
I forgot if I already asked you this, but do you have Wangtek's phone
number?
Thanks.
Dom Fontana
<– Sent from New York via AutoPilot –>
Well this thread sure got busy! The jumpers I needed were all the other
ones on the tape drive. I was finally able to get some help from the
support department from where I bought it. For some reason, it won't work
with buffered mode on a 3000. Any ideas anyone? Here's the jumper
settings:
HDR1 – 6 installed HDR2 15-16, 17-18, 19-20 installed HDR3 – (1) B-C, (2)
B-C, (3) B-C, (4) B-C E1 thru E3 jumpered E4 open E5 thru E8 jumpered E9
1-2 E10 should be 2-3 but only 1-2 works.
HDR3 sets buffered mode (1 & 4 A-B) or unbuffered mode (1 & 4 B-C) and
the tape format (2 & 3 B-C) QIC 150
(2) B-C, (3) A-B QIC 120
(2) A-B, (3) B-C QIC 24 I have had trouble in general
with BUFFERED SCSI devices on the 3000. I am using DC6250 tapes but have
not tried backing up over 150 meg as I only have a 105 meg HD. I am using
HDBackup provided on the 3000. Anyone know the street price on the
Wangtek?, How good is it, etc? Thank for your help, and it is a good to see
a review of SCSI basics from time to time in the threads for newcomers to
SCSI.
Harry M.
Harry,
I don't have an A3000 and don't know about buffered mode.
Dom Fontana
<– Sent from New York via AutoPilot –>
Dom,
Nope…it should't harm the drive at all. BTW, I've got 2 tapes
here, one is a standard DC-600, we use them at work for our 60 Meg drives
and have used them for the 120 Meg drives, we did have a few problems on
the 120 meg drives after several passes. A check with Bell Labs (it's an
AT&T system) and they said their tests showed that the DC-600's formulation
isn't "coercive" enough for the 120 for more than about 10 full
passes….after that you get problems (our experience) but that using the
DC=6320 (320 Meg tapes) worked ok, we tried them…and yes they worked
ok…but of course still only gave us 120 Meg.
You see..the DC-600's are 600 feet long, the DC-6320's are only 20
feet longer. The difference in capacity is based on the tape media
formulation being able to handle the higher density writing that a 320 meg
drive uses.
Which, of course, still leaves the issue open as to whether the
differnece between your 150 meg mode and 250 meg mode is write density or
tape length.
But I personally wouldn't worry about trying a 250 Meg tape in it
and seeing what happens.
Don
Don,
I think I understand.
You're saying we don't know if the 250-Meg tapes are just longer than
the 150-Meg tapes, but write in the same format. If they do write in the
same format, then with the extra length, I should be able to use them to
store 250-megs worth of data.
OTOH, if the 250-Meg tapes are just slightly longer, but require a tape
drive that stores the data in a more compressed format than my tape drive,
then I won't be able to use them to store 250-Megs of data. In either
case, I can't hurt my drive.
Do I have it right?
Thanks.
Dom Fontana
<– Sent from New York via AutoPilot –>
Dom,
Yes…you have it right…and I see from another user that the
6250's are in fact, longer tapes. And I also agree with that message that
over a significant period of time, if you use only one type of tape over
another type…there is a *slight* possibility that the tape wear patterns
on the head may cause you some problems.
However, these drives do not use a fixed head. The head moves up
and down an incline to step from track to track (rather than have multiple
heads or to move the tape itself) and thus I believe neither type of tape
would leave a wear pattern that would preclude the use of the other type of
tape.
That's my personal opinion…I've not tested it. I do know that we
have tape drives at work that get used for an hour or so every day. After
several years of this…I can see no significant wear on the heads.
All I see are that the heads are a bit shinier where the tape
contacts them…but no "ruts".
Don
Don,
Okay, then I'll give the 6250's a try!
Dom Fontana
<– Sent from New York via AutoPilot –>
Dominick,
The difference between the DC 6150 and DC 6250 tapes is 400 feet… 6150
tapes are 620 feet in length and 6250 tapes are 1020 feet. The
recommendation not to mix the two sizes is from some tape manufacturers and
is based on the theory that the thinner tape will over time create a
slightly different wear pattern on the head leaving the thicker 6150 media
unable to fully conform to the head.
I have not experienced this personally but it makes a warped degree of
sense. Take this info with a grain of salt that is of course if your doctor
will permit the salt ;^)
Randy Brooks
New Horizon Software, Inc.
Randy,
I did the math and it appears that the DC 6250 tapes are long enough to
store 250-Megs of data with my Wangtek 5150ES tape drive.
Even if it's true that the longer and thinner 6250 tapes will create a
different wear pattern on the head thereby rendering them unusable with
the DC 6150 tapes, it would seem that I wouldn't have any problems if I
just constantly used DC 6250 tapes and stayed with them.
I have six 6150 tapes and I have only opened one of them. Since I have
a 210-Meg harddrive, I'd like to use the 6250 tapes so I can backup the
entire HD with one tape. I'm using the latest version of QB. Do you
recommend switching over to the 6250 tapes and staying with them?
I'd like to know before opening any more of my 6150 tapes. If I can use
the 6250 tapes, I'd like to sell my 5 new and 1 used 6150 tapes and buy
six 6250 tapes.
What do you think?
Thanks for your help.
Dom Fontana
<– Sent from New York via AutoPilot –>
Dominck,
Except for my general distrust of thinner media (possibly a deepset result
of my experiences with old acetate recording media) and assuming that you
need the additional length to improve the effeciency of your backup
operations I would say that that seems to be a pretty good plan.
Randy Brooks
New Horizons Software, Inc.