Date: Sun, 9 Jan 2000 10:29:32 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: "Dave J. Boers" <djb@Wit389306.student.utwente.nl> Cc: freebsd-current@FreeBSD.ORG Subject: Re: Strange SCSI related system hang Message-ID: <200001091829.KAA19954@apollo.backplane.com> References: <20000109134916.A382@relativity.student.utwente.nl>
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:Hi all,
:
:This morning I had a very strange (at least I've never seen it before) SCSI
:related system hang. The system simply stopped responding at 9:30:03 am
:this morning. I found it in this state at 13:20. It had been hanging
:_hard_. No response to console, serial terminal or network. After a hard
:reset the system came back online normally and is working normally again.
:
:Note that the machine had an uptime of 4 days, 14 hours before the problem
:occured and it never happened before.
:
:Could this be a hardware problem?
Yes. The problem is probably termination. You have three devices
on your SCSI bus -- your hard drive should be the terminating device
and should have termination enabled. Neither of the other two devices
should have termination enabled. Alternatively, none of the devices
should have termination enabled and you should have an external active
terminator (active terminators have LEDs).
Never use a CDRom or ZIP drive to terminate a SCSI bus, they're generally
too cheap to do it right.
I am presuming that these are all internally mounted. If you have
any externally mounted SCSI devices or a combination of the two then both
ends must be terminated.
-Matt
:...
:Jan 9 04:30:01 relativity /kernel: Unexpected busfree. LASTPHASE == 0xa0
:Jan 9 04:30:01 relativity /kernel: SEQADDR == 0x151
:Jan 9 04:30:01 relativity /kernel: Unexpected busfree. LASTPHASE == 0xa0
:Jan 9 04:30:01 relativity /kernel: SEQADDR == 0x151
:Jan 9 04:30:01 relativity /kernel: Unexpected busfree. LASTPHASE == 0xa0
:...
:Jan 9 04:30:01 relativity /kernel: SEQADDR == 0x151
:Jan 9 04:30:01 relativity /kernel: ahc0:A:0: no active SCB for reconnecting target - issuing BUS DEVICE RESET
:
:...
:cd0 at ahc0 bus 0 target 1 lun 0
:cd0: <PLEXTOR CD-R PX-R412C 1.05> Removable CD-ROM SCSI-2 device
:cd0: 10.000MB/s transfers (10.000MHz, offset 8)
:cd0: Attempt to query device size failed: NOT READY, Medium not present
:WARNING: / was not properly dismounted
:da0 at ahc0 bus 0 target 0 lun 0
:da0: <WDIGTL ENTERPRISE 1.70> Fixed Direct Access SCSI-2 device
:da0: 20.000MB/s transfers (20.000MHz, offset 15)
:da0: 4157MB (8515173 512 byte sectors: 255H 63S/T 530C)
:da1 at ahc0 bus 0 target 5 lun 0
:da1: <IOMEGA ZIP 100 J.02> Removable Direct Access SCSI-2 device
:da1: 3.300MB/s transfers
:da1: 96MB (196608 512 byte sectors: 64H 32S/T 96C)
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