Hello everyone, I hope this list is the right place to ask the following: I've got a 5-disk RAID-5 array that's been built by a QNAP NAS device, which has recently failed (I suspect a faulty SATA controller or backplane). I migrated the disks to a desktop computer that runs Debian stretch (kernel 4.9.65-3+deb9u1 amd64) and mdadm version 3.4. Although the array can be assembled, I encountered the following error in my dmesg output ([1], recorded directly after a recent reboot and fsck attempt) when running fsck: Buffer I/O error on dev md0, logical block 1598030208, async page read I can reliably reproduce that error by trying to read from the md0 device. It's always the same block, also across reboots. I have suspected that possibly, one of the drives involved is faulty. Although smart errors have been logged [2], the errors are not recent enough to correlate with the fsck run. Also, I had sha1sum complete without error on every one of the individual disk devices /dev/sd[b-f], so reading from the drives does not provoke an error. Finally, I tried scrubbing the array by writing repair to md/sync_action. The process completed without any output to dmesg or signs of trouble in /proc/mdstat. However, reading from the array still fails at the same block as above, 1598030208. Here's the output of mdadm --detail /dev/md0: [3] I assume the md driver would know what exactly the problem is, but I don't know where to look to find that information. How can I proceed troubleshooting this issue? FYI, I had posted this on serverfault [4] previously, but unfortunately didn't arrive at a conclusion. Thank you very much in advance! [1] https://paste.ubuntu.com/26303735/ [2] https://paste.ubuntu.com/26303737/ [3] https://paste.ubuntu.com/26303754/ [4] https://serverfault.com/questions/889687/troubleshooting-buffer-i-o-error-on-software-raid-md-device -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
