Lustre 1.6 Operations Manual

live_router_check_interval, dead_router_check_interval, auto_down,
check_routers_before_use and router_ping_timeout
In a routed Lustre setup with nodes on different networks such as TCP/IP and Elan,
the router checker checks the status of a router. Currently, only the clients using the
sock LND and Elan LND avoid failed routers. We are working on extending this
behavior to include all types of LNDs. The auto_down parameter enables/disables
(1/0) the automatic marking of router state.
The live_router_check_interval parameter specifies a time interval in seconds
after which the router checker will ping the live routers.
In the same way, you can set the dead_router_check_interval parameter for
checking dead routers.
You can set the timeout for the router checker to check the live or dead routers by
setting the router_ping_timeout parmeter. The Router pinger sends a ping
message to a dead/live router once every dead/live_router_check_interval
seconds, and if it does not get a reply message from the router within
router_ping_timeout seconds, it considers the router to be down.
The last parameter is check_routers_before_use, which is off by default. If it is
turned on, you must also give dead_router_check_interval a positive integer value.
The router checker gets the following variables for each router:
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Last time that it was disabled
Duration of time for which it is disabled
The initial time to disable a router should be one minute (enough to plug in a cable
after removing it). If the router is administratively marked as "up", then the router
checker clears the timeout. When a route is disabled (and possibly new), the "sent
packets" counter is set to 0. When the route is first re-used (that is an elapsed disable
time is found), the sent packets counter is incremented to 1, and incremented for all
further uses of the route. If the route has been used for 100 packets successfully, then
the sent-packets counter should be with a value of 100. Set the timeout to 0 (zero), so
future errors no longer double the timeout.
Note – The router_ping_timeout is consistent with the default LND timeouts.
You may have to increase it on very large clusters if the LND timeout is also
increased. For larger clusters, we suggest increasing the check interval.
Chapter 5 Configuring the Lustre Network 5-7