mo@uunet.uu.net (Mike O'Dell) (06/07/89)
Scenario: Sun 4/280 with ALM2 muxes Add: Ciprico 3500 SCSI controller for Exabyte tape Result: Disasterous crashes: cat /usr/dict/words on a terminal and start a tar to the Exabyte. Instant flaming death. The Plan: A crack VME hacker from Ciprico came out to our site and the lot of us pulled an all-nighter. We discovered that the 3500 was NOT volating the letter of the VME protocol, but there were some suspicious bus cycles related to the ALM2 and the 3500 seen on the logic analyzers. Said ace engineer returned to Minneapolis and the following day a FedEx package arrived with a new PAL to tweek the cycle timing to be more deferential to the weird things the ALM2 does. The GOOD NEWS: Great Joy!! The PAL fixed it completely. The system is running reliably with arbitrarily many terminals catting /usr/dict/words with no ill effects, and the Exabyte just spins away. So, it seems that it IS weirdness on the part of the ALM2, but that weirdness was exacerbated by interaction with the 3500. But Ciprico fixed their board to solve the problem. I am mightily impressed with the support we have gotten from them. It wasn't their problem, per se, but they fixed it anyway. -Mike O'Dell