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authorQiaowei Ren <qiaowei.ren@intel.com>2018-01-04 13:43:33 +0800
committerQiaowei Ren <qiaowei.ren@intel.com>2018-01-05 11:59:39 +0800
commit812ff6ca9fcd3e629e49d4328905f33eee8ca3f5 (patch)
tree04ece7b4da00d9d2f98093774594f4057ae561d4 /src/ceph/doc/dev/osd_internals/pg.rst
parent15280273faafb77777eab341909a3f495cf248d9 (diff)
initial code repo
This patch creates initial code repo. For ceph, luminous stable release will be used for base code, and next changes and optimization for ceph will be added to it. For opensds, currently any changes can be upstreamed into original opensds repo (https://github.com/opensds/opensds), and so stor4nfv will directly clone opensds code to deploy stor4nfv environment. And the scripts for deployment based on ceph and opensds will be put into 'ci' directory. Change-Id: I46a32218884c75dda2936337604ff03c554648e4 Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com>
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+====
+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.