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Newsgroups: comp.os.386bsd.bugs
Path: sserve!newshost.anu.edu.au!munnari.oz.au!news.Hawaii.Edu!ames!agate!tfs.com!julian
From: julian@TFS.COM (Julian Elischer)
Subject: Bad bug in new scsi code and work-around
Message-ID: <CGyMsv.K86@tfs.com>
Sender: usenet@tfs.com
Organization: TRW Financial Systems
Date: Tue, 23 Nov 1993 19:43:43 GMT
Lines: 37
A bug has been found in the new scsi code, (presently in FreeBSD-current)
loaded by some people, which results in the following behaviour
An attempt to open a raw disk device while it is ACTIVELY being used as
a block device has a high probability of freezing all access to that disk
If it is your system disk............
The immediate symptom you will see is:
the attempt to do an fsck -n during the daily house-keeping crontab
script run at 1AM (or whenever) will probably freeze the system, requiring that
you reboot the system in the morning.
I will be working on this bug tonight and hope to have an answer soon..
if you feel like looking at it in the meanwhile.....
duplicate by:
find {some-scsi-disk} >/dev/null &
dd if=/dev/r{same-scsi-disk} of=/dev/null count=1
repeat dd until it hangs
there is the possibility that two raw operations may have the same effect
and also that just the act of openning the raw device may be enough..
I will know more tomorrow..
as long as you avoid this mode of operation, the new scsi system looks good.
julian