Below is the configuration that I used for a server with Qlogic HBA card (qla2xxx driver) and EMC Clarion SAN storage.
defaults {udev_dir /devpolling_interval 10selector "round-robin 0"path_grouping_policy failovergetuid_callout "/sbin/scsi_id -g -u -s /block/%n"prio_callout "/bin/true"path_checker turrr_min_io 100rr_weight uniformfailback immediateno_path_retry 12user_friendly_names yes}blacklist {devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"devnode "^hd[a-z]"devnode "^cciss!c[0-9]d[0-9]*"}devices {device {vendor "DGC"product ".*"product_blacklist "LUNZ"getuid_callout "/sbin/scsi_id -g -u -s /block/%n"prio_callout "/sbin/mpath_prio_alua /dev/%n"features "1 queue_if_no_path"hardware_handler "1 alua"path_grouping_policy group_by_priofailback immediaterr_weight uniformno_path_retry 60rr_min_io 1000path_checker emc_clariion}}
I was getting "Buffer I/O error on device" when using "emc" handler. Hope it may help some one.