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5e36acdb6f
I'm going to extract this logic and reuse it in crimson. Recovery* has always been a confusing name as it implements neither log-based recovery nor backfill. Rather, it's mainly the buisiness logic for agreeing on an authoritative log and some ancillary things such as scrub/backfill reservation. $ for i in $(git grep -l 'RecoveryMachine'); do sed -i 's/RecoveryMachine/PeeringMachine/g' $i; done $ for i in $(git grep -l 'RecoveryState'); do sed -i 's/RecoveryState/PeeringState/g' $i; done $ for i in $(git grep -l 'RecoveryCtx'); do sed -i 's/RecoveryCtx/PeeringCtx/g' $i; done Signed-off-by: Samuel Just <sjust@redhat.com>
32 lines
1.1 KiB
ReStructuredText
32 lines
1.1 KiB
ReStructuredText
====
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PG
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====
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Concepts
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--------
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*Peering Interval*
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See PG::start_peering_interval.
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See PG::acting_up_affected
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See PG::PeeringState::Reset
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A peering interval is a maximal set of contiguous map epochs in which the
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up and acting sets did not change. PG::PeeringMachine represents a
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transition from one interval to another as passing through
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PeeringState::Reset. On PG::PeeringState::AdvMap PG::acting_up_affected can
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cause the pg to transition to Reset.
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Peering Details and Gotchas
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---------------------------
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For an overview of peering, see `Peering <../../peering>`_.
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* PG::flushed defaults to false and is set to false in
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PG::start_peering_interval. Upon transitioning to PG::PeeringState::Started
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we send a transaction through the pg op sequencer which, upon complete,
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sends a FlushedEvt which sets flushed to true. The primary cannot go
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active until this happens (See PG::PeeringState::WaitFlushedPeering).
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Replicas can go active but cannot serve ops (writes or reads).
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This is necessary because we cannot read our ondisk state until unstable
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transactions from the previous interval have cleared.
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