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, 85 insertions, 0 deletions

diff --git a/src/ceph/doc/dev/bluestore.rst b/src/ceph/doc/dev/bluestore.rst
new file mode 100644
index 0000000..91d71d0
--- /dev/null
+++ b/src/ceph/doc/dev/bluestore.rst
@@ -0,0 +1,85 @@
+===================
+BlueStore Internals
+===================
+
+
+Small write strategies
+----------------------
+
+* *U*: Uncompressed write of a complete, new blob.
+
+  - write to new blob
+  - kv commit
+
+* *P*: Uncompressed partial write to unused region of an existing
+  blob.
+
+  - write to unused chunk(s) of existing blob
+  - kv commit
+
+* *W*: WAL overwrite: commit intent to overwrite, then overwrite
+  async.  Must be chunk_size = MAX(block_size, csum_block_size)
+  aligned.
+
+  - kv commit
+  - wal overwrite (chunk-aligned) of existing blob
+
+* *N*: Uncompressed partial write to a new blob.  Initially sparsely
+  utilized.  Future writes will either be *P* or *W*.
+
+  - write into a new (sparse) blob
+  - kv commit
+
+* *R+W*: Read partial chunk, then to WAL overwrite.
+
+  - read (out to chunk boundaries)
+  - kv commit
+  - wal overwrite (chunk-aligned) of existing blob
+
+* *C*: Compress data, write to new blob.
+
+  - compress and write to new blob
+  - kv commit
+
+Possible future modes
+---------------------
+
+* *F*: Fragment lextent space by writing small piece of data into a
+  piecemeal blob (that collects random, noncontiguous bits of data we
+  need to write).
+
+  - write to a piecemeal blob (min_alloc_size or larger, but we use just one block of it)
+  - kv commit
+
+* *X*: WAL read/modify/write on a single block (like legacy
+  bluestore).  No checksum.
+
+  - kv commit
+  - wal read/modify/write
+
+Mapping
+-------
+
+This very roughly maps the type of write onto what we do when we
+encounter a given blob.  In practice it's a bit more complicated since there
+might be several blobs to consider (e.g., we might be able to *W* into one or
+*P* into another), but it should communicate a rough idea of strategy.
+
++--------------------------+--------+--------------+-------------+--------------+---------------+
+|                          | raw    | raw (cached) | csum (4 KB) | csum (16 KB) | comp (128 KB) |
++--------------------------+--------+--------------+-------------+--------------+---------------+
+| 128+ KB (over)write      | U      | U            | U           | U            | C             |
++--------------------------+--------+--------------+-------------+--------------+---------------+
+| 64 KB (over)write        | U      | U            | U           | U            | U or C        |
++--------------------------+--------+--------------+-------------+--------------+---------------+
+| 4 KB overwrite           | W      | P | W        | P | W       | P | R+W      | P | N (F?)    |
++--------------------------+--------+--------------+-------------+--------------+---------------+
+| 100 byte overwrite       | R+W    | P | W        | P | R+W     | P | R+W      | P | N (F?)    |
++--------------------------+--------+--------------+-------------+--------------+---------------+
+| 100 byte append          | R+W    | P | W        | P | R+W     | P | R+W      | P | N (F?)    |
++--------------------------+--------+--------------+-------------+--------------+---------------+
++--------------------------+--------+--------------+-------------+--------------+---------------+
+| 4 KB clone overwrite     | P | N  | P | N        | P | N       | P | N        | N (F?)        |
++--------------------------+--------+--------------+-------------+--------------+---------------+
+| 100 byte clone overwrite | P | N  | P | N        | P | N       | P | N        | N (F?)        |
++--------------------------+--------+--------------+-------------+--------------+---------------+