Date: Fri, 27 Dec 1996 22:28:28 +1030 (CST) From: Michael Smith <msmith@atrad.adelaide.edu.au> To: joerg_wunsch@uriah.heep.sax.de Cc: freebsd-scsi@FreeBSD.org, msmith@atrad.adelaide.edu.au Subject: Re: cvs commit: src/sys/scsi cd.c Message-ID: <199612271158.WAA27787@genesis.atrad.adelaide.edu.au> In-Reply-To: <199612251005.LAA16758@uriah.heep.sax.de> from J Wunsch at "Dec 25, 96 11:05:03 am"
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J Wunsch stands accused of saying: > (Moved to -scsi) Tks. Should have done that myself (lazy bum that I am). > > > Slightly re-order the sequence of commands issued, so try to send > > > the START UNIT command before testing whether the device is ready. > > > Maybe it should be done even earlier, i'm not 100 % sure. > > > > >From recent experience with a box full of disks jumpered to spin up on > > command (inadequate power supply), I'd really appreciate it if the > > START UNIT command could be sent during the probe, followed by a > > _long_ wait for the drive to become ready. > > But that's a little unrelated to this commit, right? This one was for > CDs. However, it looks as if the original drivers for sd/cd/od were > all cloned from the same, and thus inherited all the bugs... so i > think the same problem still exists in the sd driver. The "unit is not spinning" status should probably be an error/status return to the generic SCSI layer in the "ideal world". I haven't looked at Justin's new SCSI code, so I don't know if this is already the case. > Why do you want to have the disks spun up at probe time? IMHO, Because there are no other demands on the system at that point in time. As far as I'm concerned, a disk that is not spinning when it's accessed is lying down on the job, and should be prodded accordingly. Stefan's point about some disks being touchy about START UNIT is also a good one; at probe time the environment surrounding the disks is quiet and well-controlled. > it's in the function scsi_start_unit() in sys/scsi/scsi_base.c. Feel > free to bump this to 60 seconds once you know what you need. If I can find a card for the Sabre, I'll check it out. As it stands just now, I ripped the PSU out of the box and jumpered all the disks to start at poweron. Now I have to deal with the one that overheats and spins down after a couple of days. *grumble*. > (I think you could experiment with a change to the sd driver that is > similar to the cd driver change we're discussing about here.) I think I was trying to resolve an over-complicated issue on simplistic principles. If/when I get a chance to play with it again, I'll think more carefully about it. > cheers, J"org -- ]] Mike Smith, Software Engineer msmith@gsoft.com.au [[ ]] Genesis Software genesis@gsoft.com.au [[ ]] High-speed data acquisition and (GSM mobile) 0411-222-496 [[ ]] realtime instrument control. (ph) +61-8-8267-3493 [[ ]] Unix hardware collector. "Where are your PEZ?" The Tick [[
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