sd_max_throttle -- The sd_max_throttle variable sets the maximum number of commands that the SCSI sd driver will attempt to queue to a single HBA driver. The default value is 256. This variable must be set to a value less than or equal to the maximum queue depth of each LUN connected to each instance of the sd driver. If this is not done, then commands may be rejected because of a full queue condition and the sd driver instance that receives the queue full message will throttle down sd_max_throttle to 1. This obviously will result in degraded performance. The variable is set in the /etc/system file as follows:

set sd:sd_max_throttle=20

sd_io_time -- The sd_io_time variable is command time out value. Setting this time out value to 120 seconds will prevent the host from issuing warning messages while non-disruptive operations are performed on the disk array. For example, in a EMC Symmettrix power path environment this variable can be set to 0x3C (60 seconds). As with the sd_max_throttle value, this is set in the /etc/system file. Using the EMC value in an example:

set sd:sd_io_time = 0x3C