Recover RAID6 with 4 disks removed
From: Nicolas Karolak <hidden>
Date: 2020-02-06 13:46:51
Hello, 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):
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
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? Any help is really appreciated. Thanks in advance. Regards, Nicolas KAROLAK