Basic Info
1)Experiment ran on trace taken from iotta.snia.org/traces/388 (MSR Cambridge trace)
2)The above site has traces of 36 disks over a period of 1 week
3)I used the first 4 hours of the 6 out of the 36 disks

Results
1)The relevant plots are included in the plots directory with the following nameing convention
<prewarm-set-size>-<prewarm-rate>-<heuristic>-<info>
where info can be
hr-5 -> shows the hit ratio during the 5 minutes after failure in the 3 cases(with pre-warming, without pre-warming, no failure)
hr-10 -> shows the hit ratio during the 10 minutes after failure in the 3 cases
hr-15 -> shows the hit ratio during the 15 minutes after failure in the 3 cases
hr -> shows the hit ratio for the entire 1 hour duration in the 3 cases
vdisk-hr5-wop -> shows the hit ratio(without pre-warming) for each vdisk during the 5 minutes after failure
vdisk-hr5-wp -> shows the hit ratio(with pre-warming) for each vdisk during the 5 minutes after failure
vdisk-hr -> shows the hit ratio(with pre-warming) for each vdisk during entire 1 hour duration

Key observations
1)An important observation about the trace is that the iops values are very low. The largest IOPS value among the disk I chose is 18
2)Pre-warming seems to take the hit ratio to a very large value almost intantly.
3)The time taken to reach the hit ration just before failure in the case of no-prewarming is around 2 hours.
4)All this(along with the results of real2) suggests IOPS maybe a very important factor in determing how effective pre-warming is going to be.
5)In real1 we observed, IOPS were around 700-900 and pre-warming gave very litte benefit, but here with low values IOPS we are getting huge benefits.
6)Small IOPS may also mean a small wss(if we define it to be the size of the active portion of the disk in a certain time window)

Things to think about
1)Should we experiment with all the 36 disks instead of choosing only 6. IOPS per disk maybe low because load is distributed over many disks and choosing only 
a few disks may be giving positive results only because we aren't really using the true workload.