friedl@vsi.COM (Stephen J. Friedl) (10/24/88)
Hiho net.folks,
These are some first impressions of the 120MB SCSI cartridge
tape drive available for the 3B2. A customer with 240MB of
internal drives was losing his mind backing up a very large
database, and it took five or six tapes plus hours and hours. He
ordered a 120MB tape drive, and we installed it on Friday.
We installed the SCSI host adaptor, software, and tape
drive, and we were able to offload 110MB of data onto one tape in
about *half an hour*. After we did this, my customer was walking
around his office, clutching the tape, saying to himself "I'm
having orgasms" :-). He'll now put the backup in the background
to run at two in the morning and he won't have to shut down the
machine every day for this.
Installation was plug-n-play with very good instructions.
The drive uses DC600A tapes but cannot read a 23MB cartridge.
These tapes do not require formatting, they don't retension upon
insertion (*yea*), and they don't wheeze like the 23MB units do.
These drives use the standard cpio command instead of
/etc/ctccpio, and doing a backup no longer trashes the machine's
performance.
We certainly don't know the long-term considerations of tape
data reliability, but it would take some pretty big problems to
shine a bad light on this drive. Hot damn, this is nice equipment.
I can provide ordering info to anybody who wants it. You
could help *me* out by sending a note to droman@vsi.com (boss)
urging him to get one of these for us :-).
Steve
--
Steve Friedl V-Systems, Inc. +1 714 545 6442 3B2-kind-of-guy
friedl@vsi.com {backbones}!vsi.com!friedl attmail!vsi!friedl
----Nancy Reagan on 120MB SCSI cartridge tape: "Just say *now*"----pim@ctisbv.UUCP (Pim Zandbergen) (10/25/88)
In article <899@vsi.COM> friedl@vsi.COM (Stephen J. Friedl) writes: >Hiho net.folks, > > These are some first impressions of the 120MB SCSI cartridge >tape drive available for the 3B2. [ much praise deleted ] All of us who upgraded from 3B2/400s to 3b2/500s or 3b2/600s know how much nicer/better/faster the built-in 60MB SCSI cartridge tape drive is over the 23MB floppy-drive-emulating tape thing used in the 400. What I'd like to know is how the 120MB tape drive compares to to the 60MB tape drive. While I'm on the subject of comparing SCSI devices for the 3B2, AT&T sells both native SCSI hard disks and ESDI hard disks that need a SCSI-to-ESDI thing like the ones that come with the 3B2/600. Does anybody have experience with both types? How do they compare in speed? -- --------------------+------------------------------------+--------------------- Pim Zandbergen | CTI Software BV | Phone: +31 70 542302 pim@ctisbv.UUCP | Laan Copes van Cattenburch 70 | Fax: +31 70 512837 ..!mcvax!ctisbv!pim | 2585 GD The Hague, The Netherlands | Telex: 32133 CTI NL
friedl@vsi.COM (Stephen J. Friedl) (10/25/88)
In article <539@ctisbv.UUCP>, pim@ctisbv.UUCP (Pim Zandbergen) writes: > What I'd like to know is how the 120MB tape drive compares to > to the 60MB tape drive. It holds twice as much :-). > While I'm on the subject of comparing SCSI devices for the 3B2, > AT&T sells both native SCSI hard disks and ESDI hard disks that > need a SCSI-to-ESDI thing like the ones that come with the > 3B2/600. Does anybody have experience with both types? > How do they compare in speed? They are the same thing; *all* the drives are ESDI. I think this is the typical SCSI-vs-ESDI confusion that pops up a lot; ESDI is a controller-to-drive interface specification, while SCSI is a host-to-peripheral spec. The following little picture shows what is happening here: *------------* | disk drive |<------ ESDI ------* *------------* | V *----------* *---------* *-----+------* | | | SCSI | | disk | | 3B2/600 |<---->| host |<---SCSI bus--->| controller | | | | adaptor | | | *----------* *---------* *------------* You can hang other peripherals (CTC, 9-track, etc.) on the SCSI bus, because this is processor and device independent. This particular disk controller is ESDI, but this is defined by the *drive*, not by SCSI. An industrious person could take an industry-standard SMD (or ST-506, or IPI, or ...) controller and hang it on the SCSI bus as well, as long as the proper drive was used. Part of this confusion is caused by the appearence of drives with SCSI interfaces. What this means is that the drive has a built-in controller, so the controller-to-interface link is hidden to you. All the 3B2s with SCSI start with the `SCSI host adaptor'. This converts the machine-specific bus (the 3B2 backplane) into a SCSI signal. From there it can go two ways: external or internal. An EXTERNAL drive is connected via the `Disk Controller Module' (DCM). This is a box that holds the controller board and power supply, and it has SCSI going in and ESDI coming out. From the ESDI ports it goes to a box that holds the drive itself; I think that a single DCM can talk to up to four ESDI drives. An INTERNAL drive has the controller card -- probably the same one in the DCM box above -- mounted internally somewhere, and the SCSI hookup is a little ribbon cable. From this little board it goes to the same ESDI drives that are external, except it too has a little ribbon cable doing the talking. Note that if you're adventurous, you can probably hook up two more drives "internally" if you want to wire up an external power supply with a ribbon cable from the internal controller. *Whew*. A little of this is speculation, so those In The Know are encouraged to post/mail their updates. Steve -- Steve Friedl V-Systems, Inc. +1 714 545 6442 3B2-kind-of-guy friedl@vsi.com {backbones}!vsi.com!friedl attmail!vsi!friedl ----Nancy Reagan on 120MB SCSI cartridge tape: "Just say *now*"----
len@netsys.COM (Len Rose) (10/25/88)
pim@ctisbv.UUCP (Pim Zandbergen) writes:
"All of us who upgraded from 3B2/400s to 3b2/500s or 3b2/600s
know how much nicer/better/faster the built-in 60MB SCSI
cartridge tape drive is over the 23MB floppy-drive-emulating tape thing
used in the 400."
Will the 60 MB scsi tape drive fit in the same physical location as
the older 23 mb drive. I.E. If I buy a scsi tape can I install it
in place of the old drive.
"While I'm on the subject of comparing SCSI devices for the 3B2,
AT&T sells both native SCSI hard disks and ESDI hard disks that
need a SCSI-to-ESDI thing like the ones that come with the
3B2/600. Does anybody have experience with both types?"
Whose drives does AT&T use.. CDC or?
Has anyone been successful in using other brands of drives than the
one supplied by AT&T for the SCSI XM packages.. I understand that
if you want to use ESDI drives with the SCSI controller you have to
use some sort of bridging adapter. We have some Micropolis 1355's
(170 mb) that we would like to use and I am wondering if they can be
made to work with the AT&T scsi interface. Is the bridging adapter
(for scsi to esdi) available seperately?
Len Rose - Netsys,Inc.
len@ames.arc.nasa.gov or len@netsys.com