dm mpath: delay activate_path retry on SCSI_DH_RETRY
This patch adds a user-configurable 'pg_init_delay_msecs' feature. Use this feature to specify the number of milliseconds to delay before retrying scsi_dh_activate, when SCSI_DH_RETRY is returned. SCSI Device Handlers return SCSI_DH_IMM_RETRY if we could retry activation immediately and SCSI_DH_RETRY in cases where it is better to retry after some delay. Currently we immediately retry scsi_dh_activate irrespective of SCSI_DH_IMM_RETRY and SCSI_DH_RETRY. The 'pg_init_delay_msecs' feature may be provided during table create or load, e.g.: dmsetup create --table "0 20971520 multipath 3 queue_if_no_path \ pg_init_delay_msecs 2500 ..." mpatha The default for 'pg_init_delay_msecs' is 2000 milliseconds. Maximum configurable delay is 60000 milliseconds. Specifying a 'pg_init_delay_msecs' of 0 will cause immediate retry. Signed-off-by:Nikanth Karthikesan <knikanth@suse.de> Signed-off-by:
Chandra Seetharaman <sekharan@us.ibm.com> Acked-by:
Mike Christie <michaelc@cs.wisc.edu> Signed-off-by:
Mike Snitzer <snitzer@redhat.com> Signed-off-by:
Alasdair G Kergon <agk@redhat.com>
parent
052189a2
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