The current Red Hat qlogic driver doesn't support most of the adjustable parameters. However, the one you can download from qlogic does. Red Hat will include this driver in its next release (beta in about a week, production in mid-September). In addition, Red Hat will support multipathing to at least same level as what SuSe supports today: http://portal.suse.com/sdb/en/2005/04/sles_multipathing.html
I haven't used a QLogic driver with those tunables, and the ones shown to me via `modinfo qla2xxx` have been sufficient for fixing most of our latency related problems. I don't believe any of these tunables will be able to fix this problem though. Both paths go down in the same second, so there is no way to support the device. On that note however, I assume the U2 release will have both the mpath driver and the QLogic driver updated?
Red Hat is just a bit behind, but if you really need this in production, I'd suggest you contact your support and/or sales rep to ask them to support you with the beta release. How much luck you'll have, I don't know.
All I really care about is getting a workaround, or getting a redhat kernel which is at least on par with a stable vanilla release of Linux. Having consistently subpar stable releases of redhat software, and absolutely no option to bring it up to the quality of a stable Linux release is possibly going to result us in switching our contracts at this point. I have contacted support, and am still waiting for some kind of response. Last time we talked with them about multipath support, they said to wait for U1 then it'd be good. Now we get to start over? :)
Thanks, -Alan
