From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lars Marowsky-Bree Date: Wed, 4 Nov 2009 22:29:41 +0100 Subject: [Cluster-devel] SCTP versus OpenAIS/corosync time-outs In-Reply-To: <4AEE9B47.6060206@redhat.com> References: <20091031002025.GS14882@suse.de> <4AEE9B47.6060206@redhat.com> Message-ID: <20091104212941.GD32760@suse.de> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On 2009-11-02T08:41:43, Christine Caulfield wrote: >> No concurrently active transmission ("rrp_mode active") - I wonder if it >> is possible to put SCTP into such an mode, or, vice-versa, if this means >> the DLM might be better off directly opening several TCP connections on >> its own (and using them all at once, simply discarding duplicate >> messages)? > If you want to add TCP multi-homing code to the DLM, feel free. But it'll > be complicated and messy I promise. And it seems pointless to reimplement > all the sort of failover code that's already in SCTP for free. Well, the thing is that active/active doesn't seem to be something SCTP actually _can_ do, while quite obviously being the thing we'd want. I'd love to be proven wrong about SCTP, of course, that'd make things easier. >> I'm not sure what kind of problems exist, if any, but this may be a >> worth-while thing to consider or at least contemplate. I welcome >> feedback ;-) > To be honest, RRP & DLM/SCTP is not well tested or used. There are probably > lots of things that could be done to improve it. In particular the failover > aspect of it (the most important part of course) has probably not been > tried under any sort of serious load ... though i could be wrong. Yeah, I'm trying to scope what needs to be tested and improved. (Having OpenAIS+DLM run over bonding is mostly fine, but bonding is sometimes the problem, and doesn't support all topologies; hence the need to explore SCTP, or if SCTP can't do that, some alternative.) A quite different trick for redundant networking would be to assign static addresses to lo:X and run OSPF over all links, and having DLM connect to the static IPs. That's quite trivial to setup, give us "resilient" TCP (w/o needing to mess with SCTP, bonding, or anything). Comments? Regards, Lars -- Architect Storage/HA, OPS Engineering, Novell, Inc. SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG N?rnberg) "Experience is the name everyone gives to their mistakes." -- Oscar Wilde