On Tue, Jul 20, 2010 at 5:29 PM, James Howells <james@xxxxxxxxxxxxxx> wrote: > Hi everyone. > > Fantastic job with the Linux mdadm tool but I've got a problem that I need > some support with. > > (Before you all ask, I've Googled this one to death, so please don't think of > me as ignorant and blind). > > Basically, I have a 5 disk RAID-5 array in an Addonics external enclosure. > Each disk is 1TB in size. Since I am running it over USB, it's takes 3-3.5 > days to resync the disks if something goes pear-shaped. > > Now, I don't think the software is at fault because I've had the drive > replaced with a brand new disk and it's doing the exact same thing - > drive /dev/sde loses it's partition data (the drive's superblock) and the md > device's superblock. The data is unaffected since I only ever mount the > device as read-only unless I need RW capability. I physically power the > device down after unmounting the partition and stopping the array. > > Whilst other people have had this problem of drives suddenly "losing > everything", they have been able to recover, but I cannot keep my computer > running for 3-3.5 days just to rebuild good data! > > My question is: > > Is it possible to copy the md superblock from one known good drive to another > and assemble it as forced-clean? > > It's easy enough to recreate the partition table with a simple: > > dd if=/dev/sda of=/dev/sde count=1 bs=512 > > command but I believe the mdadm superblock lives at the end of the drive and > if I could recreate that then I could at least recover from a failure of a > known-good drive without needing a resync. > > I'm looking into getting the RAID controller card (actually an eSATA 5-1 mini > card) replaced or repaired but in the meantime, I am exploring all avenues. > > This only happens on /dev/sde and not on any other device. Swapping hard > drives around doesn't make any difference either - /dev/sde is perfectly > readable. Clearly, though, I am not happy about building an array with a > drive in that "cursed" slot since the loss of another drive in a RAID-5 would > destroy everything stored on the array. > > Any advice would be gratefully appreciated. > > Regards, > > James > > PS. I'm running Debian Lenny 2.6.26-2-686 32-bit kernel with mdadm version > 2.6.7.2-3 (repackaged for Debian). > -- > 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 > James, Search the LKML for my thread "Drives missing at boot" to see if you have a problem similar to the one Paul and I have had. If so there is a kernel patch in the thread which addresses the issue and seems to work. We both have Asus MBs, new, fast i7 9xx processors, and ran into this problem. In my case drives that were found at boot always continues to work. The problem I had was they go missing at boot time and then I'd have to add them back in and do rebuilds, 5 a week at times. Anyway, I hope it helps. If not good luck in your search. Cheers, Mark -- 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
