> yeah, i think this data corruption could/should be implemented as > badblocks... > do you have a disk that read blocks with wrong data like you told? All of them were replaced during the warranty period ... but it seems I have a new candidate. I'll use it for my tests. I'll write specific data there and then I'll be reading them with sufficient idle time intervals until I get either a read error or corrupted data without read errors. > if yes, could you check if it have bad blocks? (via some software, > since i don´t know if linux kernel will report it as badblock on > dmesg or something else) I always check S.M.A.R.T. atributes and all of the drives reported reallocated and pending sectors, while there were no uncorrectable sectors reported in some cases. I remember, that one of the drives stopped booting because of MBR corruption, but the sector was readable with dd without problems. I could also clean it and created new partition table with fdisk (but the SMART atributes didn't change with the new write operation. That really looks like there was a reallocation done prior to my checks even if reallocations should be done only during the write operation and I'm sure there was absolutely no need for writing to MBR. I suspect some of the drive firmwares, that they do the reallocation transparently during the idle state. Especially seagate drives with capacities around 200GB can be heard, that they're doing their own surface checks when they're idle. Maybe that's intention of the manufacturers. I could imagine they don't want people to claim for the drive replacement and thus they're trying to cover the issues up. I also believe, that the SMART attributes might be intentionally misreported by the firmware. The drive's electronics might be transparently doing a lot of internal stuff dependent on the current drive's internal design, that can't be easily mapped to any of the SMART attributes and thus not reported at all. You know, nobody can make the manufacturers to follow the rules ... moreover, there might be a design/firmware bug or something else preventing the drive working correctly in some cases. I can imagine many different scenarios since I was a hardware designer for almost 10 years and writing a firmware for conceptually wrong hardware design might be the worst nightmare you could ever imagine. And low-price device designs are often cheated and full of workarounds. Anyway ... I believe, that relying on (by nature) unreliable hardware might be considered a conceptual issue of the current MD-RAID layer. > -- > Roberto Spadim > Spadim Technology / SPAEmpresarial > Regards, Jaromir. -- 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
