neese@adaptx1.UUCP (06/11/91)
>>>It is too much if you have to reboot your machine (for various reasons) >>>several times an hour (or even several times a day), especially if you >>>know the devices are ready! > >>How do you know they *are* ready? > >>... If you are rebooting your system this often, >>and you find the delay on startup while the system is probing for SCSI >>disks intolerable, then perhaps you ought to get a different hard drive >>setup. > >The 154[02][ab] are rather dumb in this respect. I have one in my xenix >box. My NeXT on the other hand assumes that there is at least one bootable >device out there and waits only 'til this one reports ready. Works well so >far. I can't think of any reason the 1540 series boards don't do this. The 154x adapter cannot assume anything. It may be co-existing with a standard controller, may not have a disk attached (disable BIOS in this case), more than 2 disks may already be in the system, the disks may take a long time to be ready (up to 45 seconds for some) and so on. If we knew what disks were going to be used, it would make life easier, but we have no control over this. Some drives will give selection timeouts until they are ready, others do it correctly by having the controller tell us its busy. Of course, we have no recourse but to wait until the drive controller tells us it is ready. If we took any shortcuts, we would get so many complaints about such and such device doesn't boot off of your card. Bottom line: We can't boot until the device is ready. We wait no longer than we have to, but we will wait up to 60 seconds for the device to become ready, if it reports to us it is busy. We don't have the luxury of knowing there is a device at aby given target ID, as there is no type of setup for this in PC systems. Roy Neese Adaptec Senior SCSI Applications Engineer UUCP @ neese@adaptex uunet!cs.utexas.edu!utacfd!merch!adaptex!neese