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Testing srp fail-over with dm-multipath/multipathd/srp_daemon, the
current srp implementation will take average 3-5 minutes to complete the
error recovery before return DID_BAD_TARGET so that dm-multipath can
switch to other paths. During this error recovery, there is no I/O
happening (old and new I/Os)
The following patches attempt to help srp fail-over faster and
controllable. It introduces srp_dev_loss_tmo module parameter, so that,
srp will fail-over after srp_dev_loss_tmo expired.The minimum value for
srp_dev_loss_tmo is 60 seconds.
Patch 1/4: recreate qp and cq at reconnect instead of reuse them
Patch 2/4: disconnect request without wait.
Patch 3/4: introducing srp_dev_loss_tmo, creating a timer on qp_error event.
Patch 4/4: setting up async event handler to handle local port up/down
events
The fail-over will be more accurate on local port up/down events (ie.
someone pull the cable connect local port to switch), it is less
accurate on target port up/down events (ie. someone pull the cable
connect target port to switch)
To be accurate on target port up/down events, it requires to change
srp_daemon to catch the event of IB target port joining/leaving the
fabric, then pass these event down to srp driver, srp driver need to
implement entry points to receive these events and act upon them. These
are missed on this attempt
thanks,
-vu
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