Dear Chris,

In message [ref] you wrote:

quoted

The mismatch number is not divisible by 16, yet your chunk size is

16KB. It is divisible by 4 and 8, so I'm going to guess that the
physical sector size is 4096 bytes. If correct, I'm coming up with a
maximum of 346GiB worth of sectors may be adversely affected, assuming
every sector in the mismatch count is bad (which is probably not true,
but could be).

Since the upgrade to Fedora 18 for this particular RAID 6, can you
estimate how much data has been written to the array? Could it be in the
90GiB to 350GiB range?

No.  Much less has been written.  But then, your calculation above is
wrong - these are 510 byte sector disks.

man 4 md says the same, for raid 5 and 6, mismatches are not expected to
be software problems, but much more likely hardware. But if it's true
that the OP's problems started exactly with the upgrade to Fedora 18,
that it could be a device driver. What HBA is being used?

Correct, the hardware has not been changed, and has been running fine
for many months before,

Two of the systems use a Marvell Technology Group Ltd. MV88SX6081
8-port SATA II PCI-X Controller; the third system uses a LSI Logic /
Symbios Logic SAS1068E PCI-Express Fusion-MPT SAS controller.

Best regards,

Wolfgang Denk

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