RepoMirrors/ceph
1
0
Fork 0
mirror of https://github.com/ceph/ceph synced 2025-03-25 11:48:05 +00:00
Code Issues Packages Projects Releases Wiki Activity

doc/rbd: improve grammar in "immutable object..."

Browse Source 
Improve the grammar in the "Immutable Object Cache Daemon" section.

Signed-off-by: Zac Dover <zac.dover@gmail.com>
This commit is contained in:
Zac Dover 2022-11-20 16:59:00 +10:00
parent cf5e7ad0ec
commit 3fc21e539d
1 changed files with 18 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
doc/rbd/rbd-persistent-read-only-cache.rst
View File

@ -50,29 +50,30 @@ Introduction and Generic Settings
---------------------------------
The ``ceph-immutable-object-cache`` daemon is responsible for caching parent
image content within its local caching directory. For better performance it's
recommended to use SSDs as the underlying storage.
image content within its local caching directory. Using SSDs as the underlying
storage is recommended because doing so provides better performance.
The key components of the daemon are:
#. **Domain socket based IPC:** The daemon will listen on a local domain
socket on start up and wait for connections from librbd clients.
#. **Domain socket based IPC:** The daemon listens on a local domain socket at
startup and waits for connections from librbd clients.
#. **LRU based promotion/demotion policy:** The daemon will maintain
in-memory statistics of cache-hits on each cache file. It will demote the
cold cache if capacity reaches to the configured threshold.
#. **LRU based promotion/demotion policy:** The daemon maintains in-memory
statistics of cache hits for each cache file. It demotes the cold cache
if capacity reaches the configured threshold.
#. **File-based caching store:** The daemon will maintain a simple file
based cache store. On promotion the RADOS objects will be fetched from
RADOS cluster and stored in the local caching directory.
#. **File-based caching store:** The daemon maintains a simple file-based cache
store. On promotion, the RADOS objects are fetched from RADOS cluster and
stored in the local caching directory.
On opening each cloned rbd image, ``librbd`` will try to connect to the
cache daemon through its Unix domain socket. Once successfully connected,
``librbd`` will coordinate with the daemon on the subsequent reads.
If there's a read that's not cached, the daemon will promote the RADOS object
to local caching directory, so the next read on that object will be serviced
from cache. The daemon also maintains simple LRU statistics so that under
capacity pressure it will evict cold cache files as needed.
When each cloned RBD image is opened, ``librbd`` tries to connect to the cache
daemon through its Unix domain socket. After ``librbd`` is successfully
connected, it coordinates with the daemon upon every subsequent read. In the
case of an uncached read, the daemon promotes the RADOS object to the local
caching directory and the next read of the object is serviced from the cache.
The daemon maintains simple LRU statistics, which are used to evict cold cache
files when required (for example, when the cache is at capacity and under
pressure).
Here are some important cache configuration settings: