linux - Howto check disk I/O utilisation per process

Im having a problem with a stalling Linux system and I have found sysstat/sar to report huge peaks in disk I/O utilization, average service time as well as average wait time at the time of the system stall.

How could I go about to determine which process is causing these peaks the next time it happen?
Is it possible to do with sar (ie: can I find this info from the alreade recorded sar files?

Output for "sar -d", system stall happened around 12.58-13.01pm.

12:40:01          DEV       tps  rd_sec/s  wr_sec/s  avgrq-sz  avgqu-sz     await     svctm     %util
12:40:01       dev8-0     11.57      0.11    710.08     61.36      0.01      0.97      0.37      0.43
12:45:01       dev8-0     13.36      0.00    972.93     72.82      0.01      1.00      0.32      0.43
12:50:01       dev8-0     13.55      0.03    616.56     45.49      0.01      0.70      0.35      0.47
12:55:01       dev8-0     13.99      0.08    917.00     65.55      0.01      0.86      0.37      0.52
13:01:02       dev8-0      6.28      0.00    400.53     63.81      0.89    141.87    141.12     88.59
13:05:01       dev8-0     22.75      0.03    932.13     40.97      0.01      0.65      0.27      0.62
13:10:01       dev8-0     13.11      0.00    634.55     48.42      0.01      0.71      0.38      0.50

This is a follow-up question to a thread I started yesterday: Sudden peaks in load and disk block wait, I hope its ok that I created a new topic/question on the matter since I have not been able to resolve the problem yet.

Answer

If you are lucky enough to catch the next peak utilization period, you can study per-process I/O stats interactively, using iotop.