[ClusterLabs] EL6, cman, rrp, unicast and iptables

Christine Caulfield ccaulfie at redhat.com
Tue Sep 15 03:46:33 EDT 2015

On 15/09/15 01:01, Digimer wrote:
> On 14/09/15 10:46 AM, Noel Kuntze wrote:
>> Hello Christine,
>> I googled a bit and some doc[1] says that TC_PRIO_INTERACTIVE maps to value 6, whatever that is.
>> Assuming that value of 6 is the same as the "priority value", Corosync traffic should go into band 0, because
>> TOS values of 0x10 and 0x14 have "priority value" 6, too. The page[2] on lartc.org says that, too.
>> That means that at least when pfifo_fast is used, there's no need for iptables rules or tc filters to prioritize Corosync traffic manually.
>> [1] http://linux-tc-notes.sourceforge.net/tc/doc/priority.txt
>> [2] http://lartc.org/howto/lartc.qdisc.classless.html#AEN658

Thank you for checking this. I remember I did that code years ago for
cman in rhel4 but have since forgotten the exact detail of what was
going on.

> So what's the final verdict on this? I followed your back and forth, and
> it sounds like corosync uses 0, so nothing else is to be done?
> I'm also fully willing to admit that something else triggered the fault
> detection. It happened during a long live migration (actually, several
> servers back to back), so I *assumed* that was the cause. Given it was a
> cut-over weekend though, I made a mental note and went back to work. Bad
> choice... I should have snagged the logs for later investigation. =/

There are other networking scheduling algorithms, I think. Though I
haven't looked at them in detail for years now. Maybe we should
investigate and see if there is one that might be more appropriate?


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