duplicated volume samples.

[Vadim Rovachev]

When creating a volume, ceilometer adds to database duplicated samples for notifications: volume, volume.size
By example:
ubuntu@gate-devstack:~$ ceilometer sample-list -m volume.size
+-------------+------+------+--------+------+-----------+
| Resource ID | Name | Type | Volume | Unit | Timestamp |
+-------------+------+------+--------+------+-----------+
+-------------+------+------+--------+------+-----------+
ubuntu@gate-devstack:~$ ceilometer sample-list -m volume
+-------------+------+------+--------+------+-----------+
| Resource ID | Name | Type | Volume | Unit | Timestamp |
+-------------+------+------+--------+------+-----------+
+-------------+------+------+--------+------+-----------+
ubuntu@gate-devstack:~$ nova volume-create 1
+---------------------+--------------------------------------+
| Property | Value |
+---------------------+--------------------------------------+
| attachments | [] |
| availability_zone | nova |
| bootable | false |
| created_at | 2013-12-16T12:22:14.519283 |
| display_description | None |
| display_name | None |
| id | 4476c077-11ac-4bed-b9df-d708497f8390 |
| metadata | {} |
| size | 1 |
| snapshot_id | None |
| source_volid | None |
| status | creating |
| volume_type | None |
+---------------------+--------------------------------------+
ubuntu@gate-devstack:~$ ceilometer sample-list -m volume.size
+--------------------------------------+-------------+-------+--------+------+----------------------------+
| Resource ID | Name | Type | Volume | Unit | Timestamp |
+--------------------------------------+-------------+-------+--------+------+----------------------------+
| 4476c077-11ac-4bed-b9df-d708497f8390 | volume.size | gauge | 1.0 | GB | 2013-12-16T12:22:17.366488 |
| 4476c077-11ac-4bed-b9df-d708497f8390 | volume.size | gauge | 1.0 | GB | 2013-12-16T12:22:14.839708 |
+--------------------------------------+-------------+-------+--------+------+----------------------------+
ubuntu@gate-devstack:~$ ceilometer sample-list -m volume
+--------------------------------------+--------+-------+--------+--------+----------------------------+
| Resource ID | Name | Type | Volume | Unit | Timestamp |
+--------------------------------------+--------+-------+--------+--------+----------------------------+
| 4476c077-11ac-4bed-b9df-d708497f8390 | volume | gauge | 1.0 | volume | 2013-12-16T12:22:17.366488 |
| 4476c077-11ac-4bed-b9df-d708497f8390 | volume | gauge | 1.0 | volume | 2013-12-16T12:22:14.839708 |
+--------------------------------------+--------+-------+--------+--------+----------------------------+

This bug is reproduced because when creating volume in notifications queue appear two notifications: 'volume.create.start' and 'volume.create.end' and in ceilometer.volume.notifications.py variable 'event_types' contains 'volume.create.*'.
Therefore, when creating the volume are two records in the ceilometer database, first created, when appear 'volume.create.start' notification, the second created, when appear 'volume.create.end' notification.

TO RESOLVE:
Add validation that the record already exists in the database
or
Change 'volume.create.*' on 'volume.create.start' or 'volume.create.end'

[Julien Danjou (jdanjou)]

Definitely not a bug. There's no problem having a lot of samples, it can even be a safety guard.