On 03/19/2011 01:32 PM, Fabio M. Di Nitto wrote: > On 3/19/2011 6:14 PM, Digimer wrote: >> On 03/19/2011 02:34 AM, Fabio M. Di Nitto wrote: >>> Hi all, >>> >>> while discussing on linux-cluster the support of the Tripp Lite switched >>> PDU, it occurred to me that we can effectively improve (almost half) the >>> time it takes to perform power fencing of certain devices, when for >>> example, more than one PSU needs to be powered off to complete the action. >>> >>> Node X has 2 PSU. >>> >>> In our current state, the config would look like: >>> >>> <clusternode .....> >>> <fence> >>> <method...> >>> <device name="..." port="1"/> >>> <device name="..." port="2"/> >>> ..... >>> >>> it means effectively spawning, most likely the same agent, twice. >>> Increasing the time it takes to fence and maybe increasing the >>> possibility to fail to fence if the second connection fails. >>> >>> My suggestion would be to allow to specify a list of ports instead. >>> >>> <clusternode .....> >>> <fence> >>> <method...> >>> <device name="..." ports="1 2"/> >>> .... >>> >>> Either by using a new keyword "ports" or re-using "port" itself. If >>> using "port", current configuration will continue to work as-is and the >>> change effectively would not introduce any backward compatibility issue. >>> >>> This way the agent can: >>> >>> 1) connect once (reducing in most cases the ssh/telnet/whatever time) >>> 2) issue the OFF command as fast as possible (almost in parallel) >>> 3) then wait for the results. >>> >>> By adopting a list, the configuration would look cleaner too IMHO. >>> >>> A quick glance, the change should not affect fenced (David can you >>> confirm please?), and most agents could handle it via the fencing python >>> lib (Marek?). >>> >>> Does it sound reasonable? >>> >>> Cheers >>> Fabio >> >> I like this idea, but would like to suggest: >> >> * Keep 'port' for a single port, as it is, and add 'ports' for multiple >> port definitions. >> * When using ports, I'd recommend comma-separated values and >> dash-separated ranges (ie: ports="1,2", ports="1-4", ports="1,3-5") and >> combinations there-of. This strikes me as more "standard" and possibly >> less prone to typos. >> > > The only thing I have against "," or "-" is that they might be easily > part of a port name already. > > Range doesn´t make sense to me and it´s complex to interpret/implement. > How many machines have you seen around with so many PSU´s anyway that > need a range to avoid headache? (leaving aside E10K or s390 ;)). > > Fabio
Lol, I've seen up to four in n-1 setups, but you are right, it's not common enough to justify increasing complexity, so simple space-separated numbers is fine. I still argue for the "port" vs. "ports" though. :) -- Digimer E-Mail: digi...@alteeve.com AN!Whitepapers: http://alteeve.com Node Assassin: http://nodeassassin.org
