I have a few RAID-1 volumes on a MegaRAID 9270-8i that has been solid for 2 years. I just set up a new RAID-1 array a few days ago with two 1 TB Samsung SSD 850 Pro SSDs. A few days later I started noticing that some data I had just copied onto the virtual drive didn't match the original. I ran a consistency check and it found 70+ issues and apparently corrected all of them.
I temporarily connected the physical drives to a test system and checked the raw SMART values and saw nothing wrong. That doesn't completely rule out a drive problem but it's still interesting.
This brings up a few questions:
1) Since RAID-1 has no parity, I believe it's just comparing the two physical drives byte-by-byte. When it finds a discrepancy, how does it know which physical drive has the "correct" copy of the byte?
2) How do I determine the root cause of this inconsistency?
Thanks in advance!
I temporarily connected the physical drives to a test system and checked the raw SMART values and saw nothing wrong. That doesn't completely rule out a drive problem but it's still interesting.
This brings up a few questions:
1) Since RAID-1 has no parity, I believe it's just comparing the two physical drives byte-by-byte. When it finds a discrepancy, how does it know which physical drive has the "correct" copy of the byte?
2) How do I determine the root cause of this inconsistency?
Thanks in advance!