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>

1 files changed, 22 insertions, 0 deletions

diff --git a/src/ceph/doc/dev/osd_internals/pgpool.rst b/src/ceph/doc/dev/osd_internals/pgpool.rst
new file mode 100644
index 0000000..45a252b
--- /dev/null
+++ b/src/ceph/doc/dev/osd_internals/pgpool.rst
@@ -0,0 +1,22 @@
+==================
+PGPool
+==================
+
+PGPool is a structure used to manage and update the status of removed
+snapshots.  It does this by maintaining two fields, cached_removed_snaps - the
+current removed snap set and newly_removed_snaps - newly removed snaps in the
+last epoch. In OSD::load_pgs the osd map is recovered from the pg's file store
+and passed down to OSD::_get_pool where a PGPool object is initialised with the
+map.
+
+With each new map we receive we call PGPool::update with the new map. In that
+function we build a list of newly removed snaps
+(pg_pool_t::build_removed_snaps) and merge that with our cached_removed_snaps.
+This function included checks to make sure we only do this update when things
+have changed or there has been a map gap.
+
+When we activate the pg we initialise the snap trim queue from
+cached_removed_snaps and subtract the purged_snaps we have already purged
+leaving us with the list of snaps that need to be trimmed. Trimming is later
+performed asynchronously by the snap_trim_wq.
+