diff options
Diffstat (limited to 'src/ceph/doc/dev/osd_internals/osd_overview.rst')
| -rw-r--r-- | src/ceph/doc/dev/osd_internals/osd_overview.rst | 106 |
1 files changed, 0 insertions, 106 deletions
diff --git a/src/ceph/doc/dev/osd_internals/osd_overview.rst b/src/ceph/doc/dev/osd_internals/osd_overview.rst deleted file mode 100644 index 192ddf8..0000000 --- a/src/ceph/doc/dev/osd_internals/osd_overview.rst +++ /dev/null @@ -1,106 +0,0 @@ -=== -OSD -=== - -Concepts --------- - -*Messenger* - See src/msg/Messenger.h - - Handles sending and receipt of messages on behalf of the OSD. The OSD uses - two messengers: - - 1. cluster_messenger - handles traffic to other OSDs, monitors - 2. client_messenger - handles client traffic - - This division allows the OSD to be configured with different interfaces for - client and cluster traffic. - -*Dispatcher* - See src/msg/Dispatcher.h - - OSD implements the Dispatcher interface. Of particular note is ms_dispatch, - which serves as the entry point for messages received via either the client - or cluster messenger. Because there are two messengers, ms_dispatch may be - called from at least two threads. The osd_lock is always held during - ms_dispatch. - -*WorkQueue* - See src/common/WorkQueue.h - - The WorkQueue class abstracts the process of queueing independent tasks - for asynchronous execution. Each OSD process contains workqueues for - distinct tasks: - - 1. OpWQ: handles ops (from clients) and subops (from other OSDs). - Runs in the op_tp threadpool. - 2. PeeringWQ: handles peering tasks and pg map advancement - Runs in the op_tp threadpool. - See Peering - 3. CommandWQ: handles commands (pg query, etc) - Runs in the command_tp threadpool. - 4. RecoveryWQ: handles recovery tasks. - Runs in the recovery_tp threadpool. - 5. SnapTrimWQ: handles snap trimming - Runs in the disk_tp threadpool. - See SnapTrimmer - 6. ScrubWQ: handles primary scrub path - Runs in the disk_tp threadpool. - See Scrub - 7. ScrubFinalizeWQ: handles primary scrub finalize - Runs in the disk_tp threadpool. - See Scrub - 8. RepScrubWQ: handles replica scrub path - Runs in the disk_tp threadpool - See Scrub - 9. RemoveWQ: Asynchronously removes old pg directories - Runs in the disk_tp threadpool - See PGRemoval - -*ThreadPool* - See src/common/WorkQueue.h - See also above. - - There are 4 OSD threadpools: - - 1. op_tp: handles ops and subops - 2. recovery_tp: handles recovery tasks - 3. disk_tp: handles disk intensive tasks - 4. command_tp: handles commands - -*OSDMap* - See src/osd/OSDMap.h - - The crush algorithm takes two inputs: a picture of the cluster - with status information about which nodes are up/down and in/out, - and the pgid to place. The former is encapsulated by the OSDMap. - Maps are numbered by *epoch* (epoch_t). These maps are passed around - within the OSD as std::tr1::shared_ptr<const OSDMap>. - - See MapHandling - -*PG* - See src/osd/PG.* src/osd/PrimaryLogPG.* - - Objects in rados are hashed into *PGs* and *PGs* are placed via crush onto - OSDs. The PG structure is responsible for handling requests pertaining to - a particular *PG* as well as for maintaining relevant metadata and controlling - recovery. - -*OSDService* - See src/osd/OSD.cc OSDService - - The OSDService acts as a broker between PG threads and OSD state which allows - PGs to perform actions using OSD services such as workqueues and messengers. - This is still a work in progress. Future cleanups will focus on moving such - state entirely from the OSD into the OSDService. - -Overview --------- - See src/ceph_osd.cc - - The OSD process represents one leaf device in the crush hierarchy. There - might be one OSD process per physical machine, or more than one if, for - example, the user configures one OSD instance per disk. - |