I have Centos 7
I have a 7 drive RAID6 Array created using mdadm. (This is composed on WD 4TB Red drives)
I have setup the RAID array as a LVM PV - all this has been working well for ages.
I have almost maxed out the drive space on the LVM - what i would like to do is to add additional space as follows
1) Purchase 2 x WD RED 6TB drives, create a RAID1 set from them under mdadm 2) Present that RAID set to LVM by creating a PV on it 3) Use that additional 6TB of disk space to extend the LV
I do not however want to make the LV 6TB bigger, the end result i want to achieve is to remove one of the 4TB drives from the RAID6 array, thus effectively increasing the total disk space by 2TB.
I believe the high level steps i need to take are as follows:-
1) Create a RAID1 array (call it /dev/md1 e.g.) composed of the two 6TB drives 2) partition the 6TB to have a LVM partition 3) create a PV with the 6TB of space 4) Add the PV to the existing VG 5) Move an appropriate number of extents to the 6TB PV to free up 4TB of extents in the RAID6 VG
This is now where i start to get a bit vague - i THINK i would
6) Shrink the RAID6 VG to ensure that 4TB of disk space is available 7) Reduce the number of disks in the RAID6 array 8) Shutdown the box and remove the retired drive ?
I need to flesh out 6), 7), 8) Please and let me know if i am on the right track
The RAID6 array is healthy - i will move the retired drive across to a secondary box that performs backup functions.