Re: multipath prio_callout broke from 5.2 to 5.3

["Ty! Boyack" <ty@nrel.colostate.edu>]

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?

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?

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.

Thanks for all the help.

-Ty!

-- 
-===========================-
  Ty! Boyack
  NREL Unix Network Manager
  ty@nrel.colostate.edu
  (970) 491-1186
-===========================-