On Thu, Dec 02, 2021 at 05:04:57PM -0500, Matt Garretson wrote: > Hi, I have this RAID6 array of 6x 8TB drives: > > /dev/md1: > Version : 1.2 > Creation Time : Fri Jul 6 23:20:38 2018 > Raid Level : raid6 > Array Size : 31255166976 (29.11 TiB 32.01 TB) > Used Dev Size : 7813791744 (7.28 TiB 8.00 TB) > Raid Devices : 6 > > There is an ext4 fs on the device (no lvm). > > The array for over a year has had 40 contiguous mismatches in the same spot: > > md1: mismatch sector in range 2742891144-2742891152 > md1: mismatch sector in range 2742891152-2742891160 > md1: mismatch sector in range 2742891160-2742891168 > md1: mismatch sector in range 2742891168-2742891176 > md1: mismatch sector in range 2742891176-2742891184 If you dare to try, you can use "raid6check" which should be together with "mdadm" (at least in source form). If I recall correctly, this could check a given range (whole array will take forever) and report, if possible, *which* drive is having the mismatch. It is also possible to use it to repair the mismatch, if caused by a single drive problem. Of course, standard disclaimer is that nothing is guarantee to work as advertised. Use at your own risk... bye, pg > > Sector size is 512, so I guess this works out to be five 4KiB blocks, or > 20KiB of space. > > The array is checked weekly, but never been "repaired". The ext4 > filesystem has been fsck'd a lot over the years, with no problems. But > I worry about what file might potentially have bad data in it. There > are a lot of files. > > I have done: > > dd status=none if=/dev/md1 ibs=512 skip=2742891144 count=40 |hexdump -C > > ... and I don't see anything meaningful to me. > > I have done dumpe2fs -h /dev/md1 and it tells me block size is 4096 and > the first block is 0. So does.... > > 2742891144 * 512 / 4096 = 342861393 > > ...mean we are dealing with blocks # 342861393 - 342861398 of the > filesystem? If so, is there a way for me to see what file(s) use those > blocks? > > Thanks in advance for any tips... > -Matt -- piergiorgio
