eckert@faui43.informatik.uni-erlangen.de (Toerless Eckert) (06/08/90)
Some time ago i asked about a problem with our Sun 3/180 and it's Exabyte. The machine had an Exabyte and a shoebox connected to its se0 SCSI controller. When the Exabyte was active, for example rewinding or searching for a file, the machine would often block. The problem is, that the se VME-SCSI controller for Sun3 (and possible also sold for Sun4) does not support the DISCONNECT/RECONNECT abilities of the SCSI protocol. This caused the scsi driver in the Sun to allocate the SCSI bus during all transactions, for example the rewinding or searching for files, which do not need to hold the bus. The next effect of this was, that someone accessing the filesystem on the SCSI filesystem could possible lock the whole filesystem in the kernel during these Exabyte activites. So, if you are using a VME Sun with both exabyte (or other slow tape devices) and a SCSI disk, you are well advised to change your old se Controller against the newer si controllers, which do support the DISCONNECT/RECONNECT part of the SCSI protocol. We did this with our board on maintenance so it didn't cost us a buck. Toerless Eckert | /C=de/A=dbp/P=uni-erlangen/OU=informatik/S=eckert V.4: Noah's ark of Unix | X.400 ^ Internet> eckert@informatik.uni-erlangen.de
kevin@corp.sun.com (Kevin Sheehan {Consulting Poster Child}) (06/14/90)
He is correct for the "sc" controller, also known as the SCSI2. We have not shipped those since the *very* early sun3 line. The "se" controller is the Enet/SCSI board used on the sun3e product line which does *not* have this problem. The SCSI2 was built before SCSI controller chips existed, and for an MSI based board it was too much to ask for ATN and the DISCO/RESEL stuff as well, when it didn't exist in peripherals at the time either. sc - SCSI2 - sun2 and early sun3 VME board si - SCSI3 - sun3 VME and 3/50 3/60 SCSI se - 6U SCSI/Enet board sw - 4/110 SCSI ... >X-Sun-Spots-Digest: Volume 9, Issue 207, message 3 > >Some time ago i asked about a problem with our Sun 3/180 and it's Exabyte. >The machine had an Exabyte and a shoebox connected to its se0 SCSI >controller. When the Exabyte was active, for example rewinding or >searching for a file, the machine would often block. <more comments about disconnect and reselect not being there> Kevin Sheehan Sun Microsystems kevin@sun.com