Red Hat Bugzilla – Bug 171938
mdmonitor doesn't monitor raid 4 arrays
Last modified: 2007-11-30 17:11:16 EST
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.8b5) Gecko/20051008 Fedora/1.5-0.5.0.beta2 Firefox/1.4.1 Description of problem: mdmonitor incessantly polls raid 4 arrays that, according to /proc/mdstat, are not in need of any attention whatsoever. If left alone, it eats all available cpu issuing so many syscalls, except for the cpu it forces the md kernel threads to use to respond to its ioctls. Version-Release number of selected component (if applicable): mdadm-1.11.0-4.fc4 How reproducible: Always Steps to Reproduce: 1.Create a raid 4 array 2.Add it to /etc/mdadm.conf 3.Start mdmonitor Actual Results: It eats all cpu. strace shows it's repeatedly running: open("/dev/md17", O_RDONLY) = 3 ioctl(3, 0x80480911, 0xbfcafb50) = 0 close(3) = 0 If there are multiple raid 4 arrays, it will cycle over them all, also incessantly. Expected Results: It shouldn't keep polling arrays that are fine. Additional info:
This is most likely related to the raid arrays being level 4. That's a rarely used and mostly untested level as far as things like mdadm monitoring are concerned. I'll probably upgrade to the latest mdadm and see if it still happens then.
This report targets the FC3 or FC4 products, which have now been EOL'd. Could you please check that it still applies to a current Fedora release, and either update the target product or close it ? Thanks.
The eating all cpu time thing should be solved in later versions, however, that doesn't mean raid4 devices were properly monitored. Investigating this bug report lead me to the fact that raid4 devices in the current code were actually ignored entirely. I've modified the current mdadm to no longer ignore raid4 devices (and in fact it would ignore raid10 and raid6 devices as well). With as many redundant levels as there are now, it's become much safer to configure mdadm's monitor setup to ignore non-redundant raid types than it is to specifically select the redundant types. This correction will show up in mdadm-2.6.2-2 or later.
mdadm-2.6.2-2.fc7 has been pushed to the Fedora 7 testing repository. If problems still persist, please make note of it in this bug report.
mdadm-2.6.2-3.fc7 has been pushed to the Fedora 7 testing repository. If problems still persist, please make note of it in this bug report.
mdadm-2.6.2-4.fc7 has been pushed to the Fedora 7 testing repository. If problems still persist, please make note of it in this bug report.
mdadm-2.6.2-4.fc7 has been pushed to the Fedora 7 stable repository. If problems still persist, please make note of it in this bug report.