erik@echocen.UUCP (Erik Ch. Ohrnberger) (08/24/90)
In article <1990Aug22.061223.15564@fiver> palowoda@fiver (Bob Palowoda) writes: > > Ahh, somebody mentioned the magic word "secondary" controller. Has anyone >ever tested this setup. Say with the second disk controller on interupt 15? >ISC? ESIX? or SCO UNIX? Yes, I have. The ISC HPDD will support a secondary AT controller, given 1) secondary I/O addresses, 2) if it has a floppy controller, it must be disabled, and 3) [the biggie] a secondary interrupt (usually 15). The reason 2 is of concern is that very few controllers offer it. The only ones I've seen to date are the Adaptec 232x ESDI and 237x RLL. I have used a WD-1007 (Compaq flavor) with a 300 MB ESDI drive as primary and an Adaptec 2320 with some other flavor ESDI drive on it. Works fine, BUT... when you get both drives going at the same time (the AT controller is PIO, remember) the CPU starts to get swamped handling interrupts and moving data to/from the controllers. I found my max (raw, large-buffers) transfer rate on either drive alone was around 850 KB/sec and that both together topped out at an aggregate of about 1.3 MB/sec. This is on a 20 MHz Compaq, faster CPU would help with the interrupt overhead, but probably not with the 16-bit string moves to/from the controllers. The HPDD will also support a SCSI adapter as a secondary controller (the machine I'm writing this on has 1.4 GB of Maxtor 8380s hanging off an Adaptec 1542B in addition to the ESDI primary). For pure performance, having the first-party DMA of the 1542 off-loads BUNCHES of overhead from the CPU. I just wish I could run mine faster than 5.7 MB/sec burst rate, sniff sniff... DLP I'm looking to allow a 40 MB ST-251-1 (MFM) disk/HDFD controller to share disk activities with a ST4144-R (RLL) disk/HD controller. The way I'd like to set it up is to have the ST-251-1 be split as a 33 MB DOS volume, and a 7 MB Xenix bootstrap functions (as minimal as possible). When the Xenix boots, it would mount the RLL disk and complete it's compliment of disk and file systems. When running DOS, it would only have to worry about the 33 MB DOS partician on the ST-251-1. fdisk in the DOS and Xenix worlds should be allowed to switch active partitians, and just doing a re-boot, would allow you to switch between Xenix and DOS. Would this sort of setup apply to my configuration? Is it supported by other Unix systems? Does it void any warentees? If you have more information about accomplishing this setup, or a pointer to obtain this information in printed form with diagrams, please let me know, as I'm terrible interested. Thanks, Erik. -- Erik Ohrnberger Work: sharkey!edsews!edstip!ohrnb 2620 Woodchase Court Home: sharkey!eds.com!echocen!erik Sterling Heights, MI 48310