mirror of
https://github.com/ceph/ceph
synced 2024-12-11 14:09:09 +00:00
1c53991e4c
s/;/:/ s/up_acting_affected/acting_up_affected/ Add relative link to ../../peering http://tracker.ceph.com/issues/5058 refs #5058 Signed-off-by: Loic Dachary <loic@dachary.org>
32 lines
1.1 KiB
ReStructuredText
32 lines
1.1 KiB
ReStructuredText
====
|
|
PG
|
|
====
|
|
|
|
Concepts
|
|
--------
|
|
|
|
*Peering Interval*
|
|
See PG::start_peering_interval.
|
|
See PG::acting_up_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::acting_up_affected can
|
|
cause the pg to transition to Reset.
|
|
|
|
|
|
Peering Details and Gotchas
|
|
---------------------------
|
|
For an overview of peering, see `Peering <../../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.
|