In a real system (not zVM) this can occure if either the timeout for a Start Subchannel has elapsed OR the control unit got too many I/O requests than it can handle, and hence the "overrun" status. (in plain terms - too much activity going on with this channel). Under VM, there might be a parameter that can control virtual channel's buffer size, I am not aware of one. Linux, however, sets the timeout fixed at 2 seconds, after which this condition can occur. I would asume that someone thought this would be a reasonale value for all conditions. There is no way to change this value, as it is hardcoded inside the kernel.
Normally, this should not bring down a system, but in this case it looks either like a linux kernel bug OR mishandling of VM of a situation. == A quote an old IBM book on I/O commands: == The overrun condition occurs when the channel subsystem fails to respond to the control unit in the anticipated time interval to a request for service from the I/O device. When the total activity initiated by the program exceeds the capability of the channel subsystem, an overrun may occur when data is transferred to or from a control unit that is either using the data-streaming feature (on the parallel-I/O interface) or is not buffered. == end quote == Jacob Dekel. http://www.mvsdasd.org -----Original Message----- .... Jul 24 21:50:13 lnoaesd kernel: dasd_erp(3990): 0.0.2537: Overrun - service overrun or overrun error requested by channel Jul 24 21:50:13 lnoaesd kernel: dasd_erp(3990): 0.0.2532: Overrun - service overrun or overrun error requested by channel Jul 24 21:50:13 lnoaesd kernel: klogd 1.4.1, ---------- state change ---------- Jul 24 21:59:01 lnoaesd /USR/SBIN/CRON[16103]: (root) CMD ( rm -f /var/spool/cron/lastrun/cron.hourly) Jul 24 22:24:04 lnoaesd -- MARK -- Jul 24 22:44:08 lnoaesd -- MARK -- ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
