On mine to NETAPP:

ls /proc/scsi/qla2xxx
1
ls /proc/scsi/qla2xxx/1 | grep -i -A1 -B1 "queue depth"
Total number of interrupts = 30686605
    Device queue depth = 0x20
Number of free request entries = 1842

So x20 is 32 in decimal, This is the # you are looking for. You can read about calculation for NETAPP here:

https://library.netapp.com/ecmdocs/ECMP1196793/html/GUID-A055B184-0876-4376-9C75-35FE8C9BE832.html

EDIT: some other method to see: cat /sys/module/qla2xxx/parameters/ql2xmaxqdepth


The simplest way is

cat /sys/block/<sdX>/device/queue_depth