On Oct 26, 2011, at 18:02 , Jeffrey Altman wrote: > On 10/26/2011 10:34 AM, Booker Bense wrote: >> >> I am sure I'm far from the first person to think of this and there are >> some threads on the list about it. But has anyone >> gone to the logical conclusion for user volumes and done >> one VM , one server per user home volume ? > > This is not a practical use of resources. There is a limit of ~255 file > servers in a cell which will not cover all of the users in most cells.
Thanks, I wasn't aware of that limit - which would be quite relevant if we were serving all our data using AFS. > Fixing this requires a database upgrade and RPC updates for the > management tools. > >> A batch system of any reasonable size is pretty much a built in >> denial of service attack for the current OpenAFS implementation. > > Before deciding on a solution, what needs to be understood is which > resource or resources become the bottleneck. Only then can a proper > solution be implemented. We know there are a variety of bottlenecks in > the AFS file server: > > 1. rx related probably > 2. file server host management possibly > 3. callback processing possibly > 4. vol package > > 5. dir package can't comment on those due to lack of insight <:-) > 6. disk i/o channel unlikely > 7. mp scalability or lack thereof probably > 8. other > > which are affected by the configuration of the file server and the > system as a whole. [...] > Hosting multiple file server VMs on a machine is a practical way of > improving utilization of systems with large numbers of CPU cores. There > is no benefit in deploying shipping OpenAFS file servers on machines > with more than four cores. It has become really hard (impossible?) to purchase a decent server with no more than four cores... servers with twelve cores are the current sweet spot if the software can handle them, and next year it will be sixteen cores or more. I wonder why 128 threads (or 256 with 1.6) can't make use of more than four cores though? I asked this question at EAKCS11, but let me ask once more: Would it make sense to host, say, three AFS fileservers on a current 12-core (two socket westmere) system? -- Stephan Wiesand DESY -DV- Platanenenallee 6 15738 Zeuthen, Germany _______________________________________________ OpenAFS-info mailing list [email protected] https://lists.openafs.org/mailman/listinfo/openafs-info
