aad@stepstone.com (Anthony A. Datri) (04/04/89)
I see that there are different sets of supported disks under these two controller types in Sun's 4.0 format.dat file. The Micropolis 1355 is listed under the MD21, yet I have a Sun sheobox with a 1355 attached to an Adaptec. Is this division as arbitrary as it seems? I want to take a DEC rd53 (really a Micropolis 1325), and hang it as the second drive off of the MD21 in a Sun shoebox that already has a 1355 in it. I suspect that this'll work just fine as long as I add an entry for the 1325 off of the MD21. I can see that the smaller ribbon from the drive goes directly to the empty set of pins on the MD21, but do I have to substitute a ribbon with two connectors for the larger, with both drives chained? Does adding a second drive to the MD21 affect performance adversely? In a previous incarnation, we attached a Maxtor 1140 to an Adaptec/1325 equipped shoebox, and it seemed to work fine after we figured out the geometry.
henry@uunet.uu.net (04/24/89)
>... I want to take a DEC rd53 (really a Micropolis 1325)...
Beware: DEC is notorious for slightly modifying third-party hardware used
in its systems. That may be a Micropolis 1324.9997 or 1325.002 rather
than a 1325. (I have no specific information on the RD53, but I urge
caution.)
Henry Spencer at U of Toronto Zoology
uunet!attcan!utzoo!henry henry@zoo.toronto.eduweber@harvard.UUCP (Jeff Weber) (04/24/89)
aad@stepstone.com (Anthony A. Datri) writes: >I see that there are different sets of supported disks under these two >controller types in Sun's 4.0 format.dat file. The Micropolis 1355 is >listed under the MD21, yet I have a Sun sheobox with a 1355 attached to an >Adaptec. Is this division as arbitrary as it seems? I want to take a DEC >rd53 (really a Micropolis 1325), and hang it as the second drive off of >the MD21 in a Sun shoebox that already has a 1355 in it. I suspect that >this'll work just fine as long as I add an entry for the 1325 off of the >MD21. Interconnect stuff deleted... First off the MD-21 is a SCSI to ESDI controller and abotu twice as fast as the Adaptec 4000 which is a SCSI to St-506 controller. ST-506 and ESDI are traditionally disk interfaces and ESDI is twice as fast as ST-506 (send nit contradictions to /dev/null). You cannot intermix the drive and controllers just because the cables fit, which they do. I'm pretty sure that experimentation will lead to the purchase of a disk or controller. A 1355 is a 327MB(f) ESDI disk and a 1325 is a ~85MB(f) ST-506 disk. MD-21's don't like to have two different configurations of disks attached let alone an ST-506 added in for good measure. I'd check that you have a 1355 ESDI connected to a ST-506 Adaptec. Something is not right is that is INDEED the situation (is it really a Adaptec 4000?) and not some non-4000 controller. Jeff Weber
bzs@bu-cs.BU.EDU (Barry Shein) (05/05/89)
>Beware: DEC is notorious for slightly modifying third-party hardware used >in its systems. That may be a Micropolis 1324.9997 or 1325.002 rather >than a 1325. (I have no specific information on the RD53, but I urge >caution.) > > Henry Spencer at U of Toronto Zoology Just to add a little fairness these changes are not just arbitrary. I remember fighting with DEC field service to write a contract on a printer which was "the same damn vendor and model number" as their re-packaged version on a large Vax installation. Finally a field service person dropped by to chat and pointed out some of the differences inside. Among them were shock hazard guards which DEC had insisted on to protect their service people, and in fact I realized they were right, the original design I had did have a serious shock hazard inside. I paid to have it upgraded, and a board replaced which they said blew out too frequently in its original incarnation and we wrote the contract. I don't think any of that was unreasonable even tho I was "certain" they had just slapped their name on the outside, they hadn't, they had insisted on some significant improvements. -Barry Shein, Software Tool & Die There's nothing more terrifying to hardware vendors than satisfied customers.