Re-shape or Grow a Raid 5 array.

Increasing the capacity of Linux software RAID is not as difficult as it may seem. Suppose we have one software RAID 5 device, /dev/md0, built from three hard disks, and need more capacity for any reason. We can add as many disks as needed. Note that new disks should be the same size as the existing RAID disks. In this example, I will add one disk, /dev/sdd1. After installing it, use the following command to add it to the RAID device: #mdadm /dev/md0 -a /dev/sdd1 Next, run the command below to grow the RAID device. Here: -n is the total number of disks in the RAID device. —backup-file saves the critical section to protect the data in case of failure. #mdadm -G /dev/md0 -n4 —backup-file=/tmp/critical-section Finally, resize the filesystem with: #resize2fs /dev/md0 Once all steps are complete, run: #cat /proc/mdstat If the status is [UUUU], it is working. :)