On Wed, 16 Feb 2011 23:34:43 +0100 David Brown <david.brown@xxxxxxxxxxxx> wrote: > I thought there was some mechanism for block devices to report bad > blocks back to the file system, and that file systems tracked bad block > lists. Modern drives automatically relocate bad blocks (at least, they > do if they can), but there was a time when they did not and it was up to > the file system to track these. Whether that still applies to modern > file systems, I do not know - they only file system I have studied in > low-level detail is FAT16. When the block device reports an error the filesystem can certainly record that information in a bad-block list, and possibly does. However I thought you were suggesting a situation where the block device could succeed with the request, but knew that area of the device was of low quality. e.g. IO to a block on a stripe which had one 'bad block'. The IO should succeed, but the data isn't as safe as elsewhere. It would be nice if we could tell the filesystem that fact, and if it could make use of it. But we currently cannot. We can say "success" or "failure", but we cannot say "success, but you might not be so lucky next time". NeilBrown -- 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
