Sumeet Lahorani wrote:
We are [...] trying to simulate the effect of a bonding failover
initiated by a switch failure using echo commands in parallel to the
/sys/class/net/bond0/bonding/active_slave file on a few of the nodes
attached to the switch. Is this an acceptable technique?
yes
We are trying to avoid actually resetting the switch to avoid
affecting other nodes connected to the same switch, since the other
nodes are being used for other purposes
There's no need to reboot a switch in order to cause an IB link down
event on an HCA port across the wire connected to one of the switch
ports. You can administratively disable the switch port you want and
later administratively enable it. This is simple as
$ ibportstate disable/query/enable $LID $PORT
using the switch one and the switch port the hca port is connected to.
Would there be any difference in terms of the code path which the
bonding driver/ofed stack follows when we do this as opposed to
resetting the switch?
yes and yes.
Bonding wise, when setting the active slave through sysfs, the bonding
driver doesn't go through the link monitoring code, wheres if you do
cause a link down it does.
As for the IB stack (there's nothing like "ofed stack", ofed is just a
bunch of rpms installed over your distro), when a port goes down, things
happen... if the software you're using counts/uses IB port down events,
you may exercise a different flow, e.g IPoIB is using these events, and
you will not go through the port down flow of it. Next, if some code
you're working with uses the IB RC transport, then depending on the
timeout programmed to the RC QP, a transport timeout may happen which in
turn causes the HW to move the QP into the error state, and so on.
Or
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