Improve Compute Data Model¶
https://blueprints.launchpad.net/watcher/+spec/improve-compute-data-model
Problem description¶
The fields(vcpus, memory and disk_capacity) in the Watcher ComputeNode correspond to the fields(vcpus, memory_mb and local_gb) in Nova API list-hypervisors-details. Unfortunately, these fields do not take allocation ratios used for overcommit into account so there may be disparity between this and the used count.
Use Cases¶
As a Watcher user, I wish Watcher can work correctly in the case of overcommit resources(cpu, memory and disk).
Proposed change¶
Now Watcher had added Placement helper. Watcher can get resource information such as total, allocation ratio and reserved information from API list resource provider inventories.
Watcher ComputeNode¶
We need to add some fields to the Watcher ComputeNode:
vcpu_reserved: The amount of cpu a node has reserved for its own use.
vcpu_ratio: CPU allocation ratio.
memory_mb_reserved: The amount of memory a node has reserved for its own use.
memory_ratio: Memory allocation ratio.
disk_gb_reserved: The amount of disk a node has reserved for its own use.
disk_ratio: Disk allocation ratio.
We can calculate the total resource capacity through the total, reserved and allocation ratio.
The formula: vcpu capacity = (vcpus-vcpu_reserved)*vcpu_ratio
For example, for vcpu resource with:
vcpus = 8
vcpu_reserved = 2
vcpu_ratio = 5.0
The vcpu capacity is (8 - 2) * 5.0 = 30.
We also add some new propeties to the Watcher ComputeNode:
vcpu_capacity: The amount of vcpu, take allocation ratio into account, but do not include reserved.
memory_mb_capacity: The amount of memory, take allocation ratio into account, but do not include reserved.
disk_gb_capacity: The amount of disk, take allocation ratio into account, but do not include reserved.
Compute Data Model¶
CDM(Compute Data Model) will be built when creating audit and updated when receiving Nova notifications. So when building and updating CDM we need to get resource information from Placement API.
Alternatives¶
None
Data model impact¶
None
REST API impact¶
None
Security impact¶
None
Notifications impact¶
None
Other end user impact¶
None
Performance Impact¶
None
Other deployer impact¶
None
Developer impact¶
None
Implementation¶
Assignee(s)¶
- Primary assignee:
licanwei
Work Items¶
Add new fields to Watcher ComputeNode
Update compute collector
Update the processing about Nova notifications
Dependencies¶
None
Testing¶
Add unit test
Documentation Impact¶
None
References¶
History¶
Release Name |
Description |
|---|---|
Train |
Introduced |
