WilsonH,  To detect issues within the hard drive you will want to run the Patrol Read. The Patrol Read checks for physical disk errors that could lead to drive failure, where as the consistency check is the process by which it checks for and corrects inconsistencies between a volume and its mirror. If you have bad blocks on the drive it can explain the drive performing slower, as the controller has to write around those blocks.  Let me know if this helps.
We have a R510 with 12 HDD. A total of 4 vdisks are created, one vdisk for every 3 HDD, using RAID 5. In our case we noticed that vdisk 4 is way slower than other vdisks, even under the same read/write load. It is suspected that one physical disk might have bad medium. The questions is: is there a way to find our which particular pdisk in the vdisk might have caused the problem? Should we use patrol read, or consistency check? $ omreport storage pdisk controller=0 vdisk=4 | grep ^NameName                      : Physical Disk 0:0:9Name                      : Physical Disk 0:0:10Name                      : Physical Disk 0:0:11 Thanks,
How to check which physical disk has performance problem?