I have a customer running a 2.6.9-42.0.10.ELsmp kernel, with a MPT scsi card connected to an external array, several times so far they have gotten an error similar to this: Buffer I/O error on device dm-0, logical block 742625682 There are no errors of any type before this error, and the machine stays up and continues logging all errors (this is not the boot device). After 10-15 of these errors with various block numbers ext3 of course notices and starts giving errors that result in the filesystem failing. The setup is ext3 -> LVM -> sda NFS is also being used but I don't think it plays any part in the problem. No errors of any type are being logged for sda, and doing a dd if=/dev/sda of=/dev/null after the problem has occured before the reboot finishes with no errors being generated. They previously used XFS and got similar failures. I have searched everything I can find, and can only find that this error should not be possible by itself. Rebooting the machine fixes the problem until it happens again several days to a week later. Given no scsi errors and that the dm layer does not yell about the scsi layer below it, it really does not look like a hardware error. So far nothing synthetic has been able to duplicate the error. The machine has ecc and it is being monitored by they bluesmoke/edac modules and it not getting any memory errors. Roger -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel