Resizing DRBD
From Kyle's Wiki
Growing
1. Add your disk however you do it
vgextend /dev/sdb vg_drbd
1a. If your drbd backing storage is an LVM logical volume, then "lvresize +" it
lvresize -L 200G /dev/mapper/vg_drbd-store
2. Now grow your drbd like this:
drbd resize r0
3. Now regrow your upper logical volume, or filesystem as needed:
resize2fs /dev/drbd0
Shrinking
1. Shrink your filesystem
resize2fs /dev/drbd0 100G
2. Resize your drbd, But leave room for the metadata!!!
drbdadm resize --size=101G r0
3. Shrink your underlying disks or logical volumes
lvresize -l 100G /dev/lv...