[root@ceph-server ~]# rbd create temp/myimage201 --size 20480
[root@ceph-server ~]# rbd du temp/myimage201
NAME       PROVISIONED USED
myimage201      20480M    0

[root@ceph-server ~]# rbd map temp/myimage201
/dev/rbd0

[root@ceph-server ~]# mkdir myimage201

[root@ceph-server ~]# mkfs.ext4 -m0 /dev/rbd/temp/myimage201
mke2fs 1.42.9 (28-Dec-2013)
Discarding device blocks: done
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=1024 blocks, Stripe width=1024 blocks
1310720 inodes, 5242880 blocks
0 blocks (0.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2153775104
160 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
        4096000

Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information:
done


[root@ceph-server ~]# mount /dev/rbd/temp/myimage201 myimage201


[root@ceph-server ~]# cp file.txt myimage201/
[root@ceph-server ~]# ls -lrth myimage201/
total 1.1G
drwx------ 2 root root  16K Oct 25 15:14 lost+found
-rw-r--r-- 1 root root 1.0G Oct 25 15:17 file.txt


[root@ceph-server ~]# rbd du temp/myimage201
warning: fast-diff map is not enabled for myimage201. operation may be slow.
NAME       PROVISIONED  USED
myimage201      20480M 1252M
[root@ceph-server ~]#


[root@ceph-server ~]# df myimage201/
Filesystem     1K-blocks    Used Available Use% Mounted on
/dev/rbd0       20511312 1093660  19401268   6% /root/myimage201
[root@ceph-server ~]#


[root@ceph-server ~]# cp file1.txt myimage201/
[root@ceph-server ~]# ls -lrth myimage201/
total 2.1G
drwx------ 2 root root  16K Oct 25 15:14 lost+found
-rw-r--r-- 1 root root 1.0G Oct 25 15:17 file.txt
-rw-r--r-- 1 root root 1.0G Oct 25 15:22 file1.txt
[root@ceph-server ~]# df myimage201/
Filesystem     1K-blocks    Used Available Use% Mounted on
/dev/rbd0       20511312 2142240  18352688  11% /root/myimage201
[root@ceph-server ~]#

[root@ceph-server ~]# rbd du temp/myimage201
warning: fast-diff map is not enabled for myimage201. operation may be slow.
NAME       PROVISIONED  USED
myimage201      20480M 2276M
[root@ceph-server ~]#

[root@ceph-server ~]# rm myimage201/file1.txt
rm: remove regular file ‘myimage201/file1.txt’? y
[root@ceph-server ~]#
[root@ceph-server ~]# ls -lrth myimage201/
total 1.1G
drwx------ 2 root root  16K Oct 25 15:14 lost+found
-rw-r--r-- 1 root root 1.0G Oct 25 15:17 file.txt
[root@ceph-server ~]#
[root@ceph-server ~]#
[root@ceph-server ~]# df myimage201/
Filesystem     1K-blocks    Used Available Use% Mounted on
/dev/rbd0       20511312 1093660  19401268   6% /root/myimage201
[root@ceph-server ~]#
[root@ceph-server ~]# rbd du temp/myimage201
warning: fast-diff map is not enabled for myimage201. operation may be slow.
NAME       PROVISIONED  USED
myimage201      20480M 2276M
[root@ceph-server ~]#