On 21/09/17 01:08, Vojtěch Kletečka wrote: > Dear linux-raid subscribers, > > may I humbly request your assistance? > > I have three disks connected over usb from which I have made raid10 > array with two far coppies. Ocasionally when connecting all three > disks to another computer one or two of the disks are not visible when > creating array due to bad contacts on usb port. Sometimes also one of > the disks suddenly disconnects from the array. Why are they connected over USB? > So far I always managed to solve the problems caused by these (very > poor, I am fully aware of that now) conditions by readding disk and > letting it synchronize with other disks. But now I apparently caused a > bigger issue because I am not able to assemble the raid at all. > Raid doesn't like USB. Because USB likes dropping disks and then raid wonders where the disk has gone - sounds exactly like what's happened to you! > As far as I remember when I connected the disks today, linux detected > only one. After few tries I found right usb ports for all three disks > and they were indeed shown in output of fdisk -l. But device was not > assembled at first. I have waited a little bit and mdadm finally > assembled the device (although I am not sure if there were two or > three devices). Strangely "cat /proc/mdstat" reported that devices are > 99.something synchronized but supposedly with all blocks synchronized > (I mean both numbers were exactly the same) and 0kb speed. Weird I > thought and I issued mdadm --stop /dev/md127 because I wasn't able to > mount /dev/md127 to filesystem. > > That was last thing I was able to do with the array. After that I have > tried all possible combinations of disks, assembling and incremental > assembling with/without --force and/or --run but everything without > any results. All commands just failed, in most cases with these two > errors: > > sudo mdadm --assemble /dev/md127 /dev/sd[cde]1 > mdadm: /dev/md127 assembled from 2 drives - need all 3 to start it > (use --run to insist). > (this command caused "kicking non-fresh sdd1 from array!" in dmesg) > > sudo mdadm --assemble /dev/md127 /dev/sd[cde]1 --run > mdadm: failed to RUN_ARRAY /dev/md127: Input/output error > (this command caused "not enough operational mirrors." in dmesg) > > From various examining commands (see archive for all commands > requested in "asking for help" part of wiki here: > http://mysharegadget.com/328200519) I have concluded, that one of > disks is far behind others in synchronization and other two disks > strangely don't have enough mirrors (although I though there are > exactly two disks where each block of data is written, at least in > this case). > > sudo mdadm --examine /dev/sd[c-e]1 | egrep 'Event|/dev/sd' > /dev/sdc1: > Events : 44607 > /dev/sdd1: > Events : 36570 > /dev/sde1: > Events : 44607 > > Is there any possibility of data recovery? For example by forcing > mdamd to think that the disks are synchronized? This looks good for data recovery ... > As far as I know the disks should be synchronized because last time my > brother used the array he let it synchronize afterwards. Also I > haven't used "mdadm --create" yet as it might be dangerous and I am > not sure if all data saved in array are backed up. Thank $DEITY for that - do NOT use --create - at least don't use it if you want to recover your data !!! > > Thank you for your time and any suggestions. > Get a SATA add in card if you don't have enough SATA ports, and get rid of USB !!! I'll let others chime in on how to get your array back - IF you put the drives on SATA, I hope it's just a simple "--assemble --force" which will result in everything sorting itself out, but we'll see. But don't put USB drives into a raid array! > With kind regards, > > Vojtěch Kletečka Cheers, Wol -- 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
