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<== Date ==> <== Thread ==>

Subject: Odd problems with RHEL6 diskless machines
From: <tom.cobb@diamond.ac.uk>
To: <tech-talk@aps.anl.gov>
Date: Wed, 24 Jul 2013 14:45:40 +0000
We are having some issues with our 64 bit RHEL6 diskless machines running the RedHat MRG kernel. 

When running an IOC with just devIocStats in it, all of the scan tasks seem to pause for up to 300 seconds (about half of the pauses are between 299 and 301 seconds), then resume. During this time an existing ssh connection to the server will continue to work, but channel access monitors may time out. R3.14.8.2, R3.14.11 and R3.14.12.3 IOCs are all affected. dmesg and /var/log/messages show nothing suspicious, and cat /proc/sys/kernel/random/entropy_avail returns 3968.

We don't seem to have this problem on machines booting off a local disk with the standard RHEL6 kernel, or on RHEL5 diskless machines running the RHEL5 kernel. At the moment we haven't managed to reproduce this in a non-EPICS system or tested other permutations of kernel, word size and EPICS version.

Anyone seen anything similar or have any ideas? Why is 5 minutes special?

Thanks,
Tom Cobb



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Replies:
Re: Odd problems with RHEL6 diskless machines Andrew Johnson

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