Ceph » rbd

$ rbd create --size 20M --stripe-unit 1M --stripe-count 3 --thick-provision foo
Thick provisioning: 100% complete...done.

With fast-diff adjacent extents are reported out of order (and also aren't merged):

$ rbd diff foo
Offset    Length    Type
0         12582912  data
12582912  8388608   data
$ rbd diff --whole-object foo
Offset    Length   Type
0         1048576  data
3145728   1048576  data
6291456   1048576  data
9437184   1048576  data
1048576   1048576  data
4194304   1048576  data
7340032   1048576  data
10485760  1048576  data
2097152   1048576  data
5242880   1048576  data
8388608   1048576  data
11534336  1048576  data
12582912  1048576  data
15728640  1048576  data
18874368  1048576  data
13631488  1048576  data
16777216  1048576  data
19922944  1048576  data
14680064  1048576  data
17825792  1048576  data

This bug goes back to the introduction of fast-diff mode in 2015.