Dell PowerStore 3000T EMC PowerStore Host Configuration Guide - Page 33

fast_io_fail_tmo 15 max_sectors_kb 1024 //only for RHEL 6.9 (or later 6.x versions) and RHEL 7.4 (or later 7.x versions) }//other devices} } Parameter vendor product path_selector path_grouping_policy path_checker detect_prio failback no_path_retry rr_min_io_rq fast_io_fail_tmo max_sectors_kb Description Specifies the vendor name The below configuration applies only to PowerStore volumes. Sends the next group of I/Os to the path with the least number of outstanding I/O requests Specifies the default path grouping policy to apply to PowerStore volumes • Paths are grouped by priorities assigned by the cluster. • A higher priority (50) is set as Active/Optimized. Lower priority (10) is set as Active/Non-Optimized. Value DellEMC PowerStore queue-length 0 group_by_prio Specifies TEST UNIT READY as the default method used to determine tur the state of the paths. If set to yes, multipath will try to detect whether the device supports yes ALUA. If so, the device will automatically use the alua prioritizer. Otherwise, the prioritizer will be selected as usual. Default value is no. Manages the path group failback. Immediate refers to immediate failback to the highest priority path group that contains active paths. Immediate Specifies the number of times the system should attempt to use a 3 failed path before disabling queuing. Specifies the number of I/O requests to route to a path before 1 switching to the next path in the same path group, using request- based device-mapper-multipath. This setting should be used on systems running current kernels. On systems running kernels older than 2.6.31, use rr_min_io. Default value is 1. Specifies the number of seconds the scsi layer will wait after a problem 15 has been detected on a FC remote port before failing I/O to devices on that remote port. This value should be smaller than dev_loss_tmo. Setting this parameter to off will disable the timeout. Applies to Red Hat Enterprise Linux Release 6.9 (or later 6.x versions) 1024 and Red Hat Enterprise Linux Release 7.4 (or later 7.x versions). Sets the max_sectors_kb device queue parameter to the specified value on all underlying paths of a multipath device before the multipath device is first activated. When a multipath device is created, the device inherits the max_sectors_kb value from the path devices. Manually raising this value for the multipath device or lowering it for the path devices can cause multipath to create I/O operations larger than the path devices allow. Using the max_sectors_kb parameter is an easy way to set these values before a multipath device is created on top of the path devices and prevent invalid-sized I/O operations from being passed. If this parameter is not set by the user, the path devices have it set by their device driver, and the multipath device inherits it from the path devices. NOTE: In PowerStore cluster the maximum I/O size is 1MB. PowerStore does not set an optimal transfer size. Host Configuration for Linux 33