Date: Sat, 04 Apr 1998 13:35:32 -0100 From: Malte Lance <malte@webmore.com> To: "Bryan K. Ogawa" <bkogawa@primenet.com> Cc: questions@FreeBSD.ORG, freebsd-scsi@FreeBSD.ORG Subject: Re: Advice for diagnosing X hangs / kernel hangs? Message-ID: <3.0.32.19980404133531.0075a824@cyclone.degnet.baynet.de>
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At 12:30 03.04.98 -0800, you wrote: >> >Hm... I agree with you -- this may be a SCSI problem (see the comments in >> >-stable about SCSI stuff). >> >> ??? "-stable" ? What do you mean ??? > >BTW: -stable stands for the mailing list freebsd-stable@freebsd.org . I >recommend it if you are running anything in 2.2 , especially if you run >anything between releases. UUUuuuh ... i am running FreeBSD-2.1.5 and i am happy with it ;) I want to upgrade to something higher but not until i have found a solution for this damned freezes. >Since this may be a SCSI problem, I'll probably send a quick note to >freebsd-scsi as well. Hm ... i really should subscribe to -scsi . >> >I now have a 2nd machine so I can try to telnet when next my system hangs. >> No use. Done it already. As i said. When my machine freezes, it is like >> shock-frozen, nothing works. Not even a ping comes back when pinging >> it. Therefor I dont believe you will be able to telnet into it. >Yeah, my system just hung while running the program I supplied and it was >unpingable. > >However, this isn't the symptom that I had heard of previously in the >-stable list for SCSI bugs. It may be termination, however. So your hangs seem to be the same hangs that i see on my machine and the reason for this hangs should be the same also, without knowing what the real reason is. Our problem is definately not an OS-bug. It is a hardware-problem IMO. That hangs happen on FreeBSD as well as Win95 and always when the scsi-bus is busy with heavy load where more than one device are involved. It never happens when the scsi-bus is heavy-loaded with just one device. >> >I have also had great success in reducing my hangs by running the >> >following program from another virtual console: >> This is fighting the symptoms ... no real solution. But for the time, until >> a solution is found, it is undoubtly useful. >Yes, and if we can find a way to reliably prevent the hangs from software, >then it may help in diagnosing the cause. I dont think you can prevent the hangs by software. My problem for now is, how to reproduce that hangs on demand. Again, my candidate is noise on TERM-POWER. I have just one device that has some jumpers to play with active/passive-termination AND term-power. It is the SONY-SDT-7000 tape-drive. When terminating the scsi-bus passive, i get disastrous crashes at bootup. When terminating the scsi-bus active with term-power-jumper set to "provided" by scsi-bus, i had no hangs so far. When terminating the scsi-bus active with term-power-jumper set to "not provided" by the scsi-bus, i had that hangs. My paper of the jumper-setting on the sony-sdt-7000 is really bad, so i am not sure what the term-power-jumper and the "dc-disable"-jumper really do. I have to guess. All other devices on my bus dont have a jumper for term-power. If they are set to terminate the scsi-bus, they do it active. But i dont know, if they are getting term-power from the scsi-bus or in some other way. Further i dont know if they supply term-power to the scsi-bus. Therefor i set the sony-sdt-7000 as the terminating device. A final answer if noise on term-power is causing this hangs can be obtained by cutting the term-power-line on the scsi-cable at both ends of it. But this is an irreversible step. I am not sure if i should take that step. Do you have a device with jumpers to enable and disable term-power ? Malte Lance malte@webmore.com > >bryan k ogawa <bkogawa@primenet.com> http://www.primenet.com/~bkogawa/ > > >To Unsubscribe: send mail to majordomo@FreeBSD.org >with "unsubscribe freebsd-questions" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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