On Thu, Apr 23, 2009 at 11:27 PM, Benjamin Marzinski <bmarzins@xxxxxxxxxx> wrote: > On Thu, Apr 23, 2009 at 12:08:32PM -0600, Ty! Boyack wrote: >> This thread has been great information since I'm looking at the same type >> of thing. However it raises a couple of (slightly off-topic) questions for >> me. >> My recent upgrade to fedora 10 broke my prio_callout bash script just like >> you described, but my getuid_callout (a bash script that calls udevadm, >> grep, sed, and iscsi_id) runs just fine. Are the two callouts handled >> differently? > > Fedora 10 uses the same method as upstream, priority callouts have been > replaced by priority modules. These are dynamic shared objects that get > loaded by multipath. Because of this, multipath doesn't use a private > namespace, so it can use scripts without restrictions for the getuid_callout. > >> >> Also, is there an easy way to know what tools are in the private namespace >> already? My prio_callout script calls two other binaries: /sbin/udevadm >> and grep. If I go to C-code, handling grep's functions myself is no >> problem, but I'm not confident about re-implementing what udevadm does. >> Can I assume that since /sbin/udevadm is in /sbin that it will be available >> to call via exec()? Or would I be right back where we are with the bash >> scripting, as in having to include a dummy device as you described? > > Sorry, the C code is necessary now. > >> Finally, in my case I've got two redundant iscsi networks, one is 1GbE, and >> the other is 10GbE. In the past I've always had symetric paths, so I've >> used round-robin/multibus. But I want to focus traffic on the 10GbE path, >> so I was looking at using the prio callout. Is this even necessary? Or >> will round-robin/multibus take full advantage of both paths? I can see >> round-robin on that setup resulting in either around 11Gbps or 2 Gbps, >> depending on whether the slower link becomes a limiting factor. I'm just >> wondering if I am making things unnecessarily complex by trying to set >> priorities. > > With round-robin, you will send half your IO to the slow path. A > priority callout makes sense here. > >> Thanks for all the help. I ended up biting the bullet and writing a C program to do the priority calculations. m2c cc -- Chris Chen <muffaleta@xxxxxxxxx> "I want the kind of six pack you can't drink." -- Micah -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
