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| -rw-r--r-- | docs/development/design/inspector-design-guideline.rst | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/docs/development/design/inspector-design-guideline.rst b/docs/development/design/inspector-design-guideline.rst index 4add8c0f..faa5e424 100644 --- a/docs/development/design/inspector-design-guideline.rst +++ b/docs/development/design/inspector-design-guideline.rst @@ -31,7 +31,24 @@ Guidelines Host specific VMs list ---------------------- -TBD, see `DOCTOR-76`_. +While requirement in doctor project is to have alarm about fault to consumer in one second, it is just a limit we have +set in requirements. When talking about fault management in Telco, the implementation needs to be by all means optimal +and the one second is far from traditional Telco requirements. + +One thing to be optimized in inspector is to eliminate the need to read list of host specific VMs from Nova API, when +it gets a host specific failure event. Optimal way of implementation would be to initialize this list when Inspector +start by reading from Nova API and after this list would be kept up-to-date by ``instance.update`` notifications +received from nova. Polling Nova API can be used as a complementary channel to make snapshot of hosts and VMs list in +order to keep the data consistent with reality. + +This is enhancement and not perhaps something needed to keep under one second in a small system. Anyhow this would be +something needed in case of production use. + +This guideline can be summarized as following: + +- cache the host VMs mapping instead of reading it on request +- subscribe and handle update notifications to keep the list up to date +- make snapshot periodically to ensure data consistency Parallel execution ------------------ |