mirror of
https://github.com/ceph/ceph
synced 2025-01-08 12:10:20 +00:00
32 lines
1.1 KiB
ReStructuredText
32 lines
1.1 KiB
ReStructuredText
|
====
|
||
|
|
PG
|
||
|
|
====
|
||
|
|
|
||
|
|
Concepts
|
||
|
|
--------
|
||
|
|
|
||
|
|
*Peering Interval*
|
||
|
|
See PG::start_peering_interval.
|
||
|
|
See PG::up_acting_affected.
|
||
|
|
See PG::RecoveryState::Reset
|
||
|
|
|
||
|
|
A peering interval is a maximal set of contiguous map epochs in which the
|
||
|
|
up and acting sets did not change. PG::RecoveryMachine represents a
|
||
|
|
transition from one interval to another as passing through
|
||
|
|
RecoveryState::Reset. On PG;:RecoveryState::AdvMap PG::up_acting_affected can
|
||
|
|
cause the pg to transition to Reset.
|
||
|
|
|
||
|
|
|
||
|
|
Peering Details and Gotchas
|
||
|
|
---------------------------
|
||
|
|
For an overview of peering, see Peering.
|
||
|
|
|
||
|
|
* PG::flushed defaults to false and is set to false in
|
||
|
|
PG::start_peering_interval. Upon transitioning to PG::RecoveryState::Started
|
||
|
|
we send a transaction through the pg op sequencer which, upon complete,
|
||
|
|
sends a FlushedEvt which sets flushed to true. The primary cannot go
|
||
|
|
active until this happens (See PG::RecoveryState::WaitFlushedPeering).
|
||
|
|
Replicas can go active but cannot serve ops (writes or reads).
|
||
|
|
This is necessary because we cannot read our ondisk state until unstable
|
||
|
|
transactions from the previous interval have cleared.
|