What is the difference in detail between RAID patrol read and consistency check on Intel(R) RAID Controller RSP3MD088F?

[GLi29]

Our system uses 1x RMSP3AD160F and 2x RSP3MD088F. The system load during weekend is much low but both Patrol Read and Consistency Check still cannot be completed together during weekend. We plan to pick up one of them that suits for our system. Can you provide the detail of PR and CC?

We also observe the performance effect from PR is higher than CC. Is this expected? What causes it?

[JoseH_Intel]

Hello GLi29, Thank you for joining the community. You want to check the following information about what you are asking: Patrol read https://www.intel.com/content/www/us/en/support/articles/000005959/server-products.html Consistency check A consistency check is an operation that verifies that all stripes in a virtual drive with a redundant RAID level are consistent and that it automatically fixes any errors. The consistency check rate is the rate at which consistency check operations are run on a computer system The impact in performance depend on the parameters set on the RAID controller BIOS. It can be lowered consuming less resources but taking longer to complete. If both RAID controllers are installed in the same server probably both are performing the same task duplicating the time taken. For more detailed information about how to set up these parameters you want to check: https://www.intel.com/content/dam/support/us/en/documents/server-products/raid-products/SWUG_full_featured_entry_RAID.pdf Hope this helps Jose A. Intel Customer Support Technician Under Contract to Intel Corporation

[GLi29]

Hi Jose,

Thanks for you answer.

Here is what I find online :-

"a consistency check ONLY tests areas of the disks which contain data and parity, not unused areas of the arrays disks, a patrol read checks every sector of the involved disks. With todays larger disks the patrol read test is more important then a CC. Patrol reads find error in unused areas of the disks involved which are not normally found until the unused areas are written to or tested. Now, if enough areas are read/written to in a short period of time, and a threshold of bad areas are found, the raid will fail, especially during a rebuild. The Consistency check tool was developed in a time when disk were expected to grow to less then a hundred megabytes. Patrol reads came much latter, as the disks became much larger and raid failures were increasing, primarily during rebuilds. As to the power of each tool, Patrol Reads does most of what a CC does, an inconsistency due to a faulty read/write/or disk error will be found by a PR. As is a consistency errors not caused by a physical disk error is rare, over all consistency errors are very rare (my experience), physical sector errors are far more common."

Would be safe to only run patrol read weekly, totally skipping the consistency check at all?

Thanks,

Guofeng

[JoseH_Intel · Accepted solution]

Hello GLi29, Consistency Check verifies disks at a logical level, pretty much information only. Patrol Read check disks physically. Might be more powerful but won't tell you or fix if there are data consistency issues on the logical volumes. Their purposes are different and if you only run PR you might end up with healthy HDD that might contain broken/corrupted RAID volumes. Regards Jose A. Intel Customer Support Technician Under Contract to Intel Corporation

[JoseH_Intel]

Hello GLi29, Do you have any further details, updates, questions or comments in regards to this issue? This thread will be marked as resolved automatically in the next 72 hours if no activity is received. Regards Jose A. Intel Customer Support Technician Under Contract to Intel Corporation