Am 06.02.20 um 14:46 schrieb Nicolas Karolak: > I have (had...) a RAID6 array with 8 disks and tried to remove 4 disks > from it, and obviously i messed up. Here is the commands i issued (i > do not have the output of them): didn't you realize that RAID6 has redundancy to survive *exactly two* failing disks no matter how many disks the array has anmd the data and redundancy informations are spread ove the disks? > mdadm --manage /dev/md1 --fail /dev/sdh > mdadm --manage /dev/md1 --fail /dev/sdg > mdadm --detail /dev/md1 > cat /proc/mdstat > mdadm --manage /dev/md1 --fail /dev/sdf > mdadm --manage /dev/md1 --fail /dev/sde > mdadm --detail /dev/md1 > cat /proc/mdstat > mdadm --manage /dev/md1 --remove /dev/sdh > mdadm --manage /dev/md1 --remove /dev/sdg > mdadm --manage /dev/md1 --remove /dev/sde > mdadm --manage /dev/md1 --remove /dev/sdf > mdadm --detail /dev/md1 > cat /proc/mdstat > mdadm --grow /dev/md1 --raid-devices=4 > mdadm --grow /dev/md1 --array-size 7780316160 # from here it start > going wrong on the system becaue mdadm din't't prevent you from shoot yourself in the foot, likely for cases when one needs a hammer for restore from a uncommon state as last ressort set more than one disk at the same time to "fail" is aksing for troubles no matter what what happens when one drive starts to puke when you removed every redundancy and happily start a reshape that implies heavy IO? > I began to have "inpout/output" error, `ls` or `cat` or almost every > command was not working (something like "/usr/sbin/ls not found"). > `mdadm` command was still working, so i did that: > > ``` > mdadm --manage /dev/md1 --re-add /dev/sde > mdadm --manage /dev/md1 --re-add /dev/sdf > mdadm --manage /dev/md1 --re-add /dev/sdg > mdadm --manage /dev/md1 --re-add /dev/sdh > mdadm --grow /dev/md1 --raid-devices=8 > ``` > > The disks were re-added, but as "spares". After that i powered down > the server and made backup of the disks with `dd`. > > Is there any hope to retrieve the data? If yes, then how? unlikely - the started reshape did writes
