How to find which disk is being written to/read from in an LSI HW RAID logical volume?

On this system there is a lot of "await" which is causing slow response. i need to find out which disk behind the LSI logical volume is slowing it down... IBM blade, 2 HDD with LSI RAID (LV simple mirror) on top. On top of that is RHEL LVM. ..devices... # lsscsi [0:0:0:0] disk IBM-ESXS ST9146852SS B62C - [0:0:1:0] disk IBM-ESXS ST9146852SS B62C - [0:1:3:0] disk LSILOGIC Logical Volume 3000 /dev/sda ...RHEL LVM... # pvdisplay -v Scanning for physical volume names --- Physical volume --- PV Name /dev/sda2 VG Name VolGroup00 PV Size 135.48 GB / not usable 13.20 MB Allocatable yes PE Size (KByte) 32768 disk latency... so for this iostat output, how do i know which device in LSI LV is causing delays? avg-cpu: %user %nice %system %iowait %steal %idle 0.19 0.00 0.16 8.41 0.00 91.25 Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 0.00 4.00 0.00 12.50 0.00 272.00 21.76 7.01 1317.20 80.00 100.00 sda1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 sda2 0.00 4.00 0.00 12.50 0.00 272.00 21.76 7.01 1317.20 80.00 100.00 dm-0 0.00 0.00 0.00 0.50 0.00 4.00 8.00 10.48 62549.00 1358.00 67.90 dm-1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.45 0.00 0.00 44.50 dm-2 0.00 0.00 0.00 5.50 0.00 44.00 8.00 2.85 898.00 167.64 92.20 dm-3 0.00 0.00 0.00 1.50 0.00 12.00 8.00 0.86 573.67 336.00 50.40 dm-4 0.00 0.00 0.00 0.50 0.00 4.00 8.00 2.41 5162.00 1610.00 80.50 dm-5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00