MegaRAID consistency checking is different from Read Patrol in that consistency checking reads all portions of a stripe, computing parity from the data portions of the stripe and then comparing the computed parity to the parity read from the drive. Not valid to RAID0 of course.
If the compare fails, the computed parity is then written to the appropriate drive. This process can impact the performance on the controller.
The consistency check can be started manually or automatically, both can set/start by MegaRAID Storage Manager or MegaCli(MegaCli64), In this article, I’ll be using example of MegaCli command line.
Consistency checking is automatically started in background mode at the time a parity type logical drive is created, and at this time each parity portion of every stripe is created from the existing data portions of the stripe and written to the appropriated drive.
By default, MegaRAID consistency check is enabled to concurrent mode, runs every 168 hours at up to 30% performance impact, you can check and set the values according to your business environment.