storcon: add metric for AZ scheduling violations #9949
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erikgrinaker
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Dec 2, 2024
7018 tests run: 6710 passed, 0 failed, 308 skipped (full report)Flaky tests (8)Postgres 17
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2bebfe2 at 2024-12-02T11:36:50.612Z :recycle: |
awarus
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Dec 5, 2024
## Problem We can't easily tell how far the state of shards is from their AZ preferences. This can be a cause of performance issues, so it's important for diagnosability that we can tell easily if there are significant numbers of shards that aren't running in their preferred AZ. Related: neondatabase/cloud#15413 ## Summary of changes - In reconcile_all, count shards that are scheduled into the wrong AZ (if they have a preference), and publish it as a prometheus gauge. - Also calculate a statistic for how many shards wanted to reconcile but couldn't. This is clearly a lazy calculation: reconcile all only runs periodically. But that's okay: shards in the wrong AZ is something that only matters if it stays that way for some period of time.
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Problem
We can't easily tell how far the state of shards is from their AZ preferences. This can be a cause of performance issues, so it's important for diagnosability that we can tell easily if there are significant numbers of shards that aren't running in their preferred AZ.
Related: https://github.com/neondatabase/cloud/issues/15413
Summary of changes
This is clearly a lazy calculation: reconcile all only runs periodically. But that's okay: shards in the wrong AZ is something that only matters if it stays that way for some period of time.