From mboxrd@z Thu Jan 1 00:00:00 1970 From: andrey mirtchovski To: 9fans@cse.psu.edu Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Subject: [9fans] dd-induced hangs Date: Mon, 7 Jul 2003 16:05:59 -0600 Topicbox-Message-UUID: ed425a92-eacb-11e9-9e20-41e7f4b1d025 doing 'dd -if /dev/sdC0/arenas -of /dev/sdD0/arenas -bs 8192' hangs the system with 100% reproducibility (though each occurs after a different period of time). the arenas partition is 60GB. running the same command on smaller partitions (fossil, 13GB; isect, 3GB; 9fat, 10MB; nvram, 512B) completes successfully (at 15MB/s transfer rates). none of the processes on the machine are able to do any work, the console is updated when I hit a key (interrupts are processed), but rc doesn't get a chance to print a prompt. the load on the machine before the event wasn't high, but stats showed it peaking at 8000 just before the machine hung. things like ^T^Tp work, and in fact I've captured ^T^Tp, ^T^Tq and ^T^Tx if anyone is interested (^T^Ts doesn't work anymore? it's in the man page). starting the debugger (^T^TD) caused the machine to hang completely and irreversibly. it smells like a race, but my nose isn't that good to be absolutely sure :) andrey ps: i've turned dma off now and am runing the same thing again, but dma off means i'll be able to verify whether the command completed early tomorrow morning.