func (s *loopSuite) testCreateVolumesInsideLXC(c *gc.C, source storage.VolumeSource) {
	s.commands.expect("fallocate", "-l", "2MiB", filepath.Join(s.storageDir, "volume-0"))
	volumes, _, err := source.CreateVolumes([]storage.VolumeParams{{
		Tag: names.NewVolumeTag("0"), Size: 2,
	}})
	c.Assert(err, jc.ErrorIsNil)
	c.Assert(volumes, gc.HasLen, 1)
	c.Assert(volumes[0].VolumeInfo.Persistent, jc.IsTrue)
}

func (s *ebsVolumeSuite) createVolumes(vs storage.VolumeSource, instanceId string) ([]storage.Volume, error) {
	if instanceId == "" {
		instanceId = s.srv.ec2srv.NewInstances(1, "m1.medium", imageId, ec2test.Running, nil)[0]
	}
	volume0 := names.NewVolumeTag("0")
	volume1 := names.NewVolumeTag("1")
	volume2 := names.NewVolumeTag("2")
	params := []storage.VolumeParams{{
		Tag:      volume0,
		Size:     10 * 1000,
		Provider: ec2.EBS_ProviderType,
		Attributes: map[string]interface{}{
			"persistent":  true,
			"volume-type": "io1",
			"iops":        100,
		},
		Attachment: &storage.VolumeAttachmentParams{
			AttachmentParams: storage.AttachmentParams{
				InstanceId: instance.Id(instanceId),
			},
		},
		ResourceTags: map[string]string{
			tags.JujuEnv: s.TestConfig["uuid"].(string),
		},
	}, {
		Tag:      volume1,
		Size:     20 * 1000,
		Provider: ec2.EBS_ProviderType,
		Attributes: map[string]interface{}{
			"persistent": true,
		},
		Attachment: &storage.VolumeAttachmentParams{
			AttachmentParams: storage.AttachmentParams{
				InstanceId: instance.Id(instanceId),
			},
		},
		ResourceTags: map[string]string{
			tags.JujuEnv: "something-else",
		},
	}, {
		Tag:      volume2,
		Size:     30 * 1000,
		Provider: ec2.EBS_ProviderType,
		ResourceTags: map[string]string{
			"abc": "123",
		},
		Attachment: &storage.VolumeAttachmentParams{
			AttachmentParams: storage.AttachmentParams{
				InstanceId: instance.Id(instanceId),
			},
		},
	}}
	vols, _, err := vs.CreateVolumes(params)
	return vols, err
}

// validateVolumeParams validates a collection of volume parameters.
func validateVolumeParams(
	volumeSource storage.VolumeSource, volumeParams []storage.VolumeParams,
) ([]storage.VolumeParams, []error) {
	valid := make([]storage.VolumeParams, 0, len(volumeParams))
	results := make([]error, len(volumeParams))
	for i, params := range volumeParams {
		err := volumeSource.ValidateVolumeParams(params)
		if err == nil {
			valid = append(valid, params)
		}
		results[i] = err
	}
	return valid, results
}