X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=src%2Fceph%2Fdoc%2Fdev%2Fosd_internals%2Fbackfill_reservation.rst;fp=src%2Fceph%2Fdoc%2Fdev%2Fosd_internals%2Fbackfill_reservation.rst;h=0000000000000000000000000000000000000000;hb=7da45d65be36d36b880cc55c5036e96c24b53f00;hp=cf9dab4d4a0b8c0d48ff1212ce4816e3d3ba298b;hpb=691462d09d0987b47e112d6ee8740375df3c51b2;p=stor4nfv.git

diff --git a/src/ceph/doc/dev/osd_internals/backfill_reservation.rst b/src/ceph/doc/dev/osd_internals/backfill_reservation.rst
deleted file mode 100644
index cf9dab4..0000000
--- a/src/ceph/doc/dev/osd_internals/backfill_reservation.rst
+++ /dev/null
@@ -1,38 +0,0 @@
-====================
-Backfill Reservation
-====================
-
-When a new osd joins a cluster, all pgs containing it must eventually backfill
-to it.  If all of these backfills happen simultaneously, it would put excessive
-load on the osd. osd_max_backfills limits the number of outgoing or
-incoming backfills on a single node. The maximum number of outgoing backfills is
-osd_max_backfills. The maximum number of incoming backfills is
-osd_max_backfills. Therefore there can be a maximum of osd_max_backfills * 2
-simultaneous backfills on one osd.
-
-Each OSDService now has two AsyncReserver instances: one for backfills going
-from the osd (local_reserver) and one for backfills going to the osd
-(remote_reserver).  An AsyncReserver (common/AsyncReserver.h) manages a queue
-by priority of waiting items and a set of current reservation holders.  When a
-slot frees up, the AsyncReserver queues the Context* associated with the next
-item on the highest priority queue in the finisher provided to the constructor.
-
-For a primary to initiate a backfill, it must first obtain a reservation from
-its own local_reserver.  Then, it must obtain a reservation from the backfill
-target's remote_reserver via a MBackfillReserve message. This process is
-managed by substates of Active and ReplicaActive (see the substates of Active
-in PG.h).  The reservations are dropped either on the Backfilled event, which
-is sent on the primary before calling recovery_complete and on the replica on
-receipt of the BackfillComplete progress message), or upon leaving Active or
-ReplicaActive.
-
-It's important that we always grab the local reservation before the remote
-reservation in order to prevent a circular dependency.
-
-We want to minimize the risk of data loss by prioritizing the order in
-which PGs are recovered. The highest priority is log based recovery
-(OSD_RECOVERY_PRIORITY_MAX) since this must always complete before
-backfill can start.  The next priority is backfill of degraded PGs and
-is a function of the degradation. A backfill for a PG missing two
-replicas will have a priority higher than a backfill for a PG missing
-one replica.  The lowest priority is backfill of non-degraded PGs.