How to do it...

To increase or decrease the Ceph RBD image size, use the --size <New_Size_in_MB> option with the rbd resize command, this will set the new size for the RBD image:

1. The original size of the RBD image that we created earlier was 10 GB. We will now increase its size to 20 GB:

        # rbd resize --image rbd1 --size 20480 --name client.rbd
        # rbd info --image rbd1 --name client.rbd

1. Grow the filesystem so that we can make use of increased storage space. It's worth knowing that the filesystem resize is a feature of the OS as well as the device filesystem. You should read filesystem documentation before resizing any partition. The XFS filesystem supports online resizing. Check system messages to know the filesystem size change (you will notice df -h shows the original 10G size even though we resized, as the filesystem still see's the original size):

         # df -h
         # lsblk
         # dmesg | grep -i capacity
         # xfs_growfs -d /mnt/ceph-disk1