From f31aa727b08919cb0658dc8cbcdaf2087cc41248 Mon Sep 17 00:00:00 2001 From: Ilya Dryomov Date: Thu, 6 May 2021 11:20:23 +0200 Subject: [PATCH] doc/rbd/rbd-persistent-write-back-cache: clarify some config settings Signed-off-by: Ilya Dryomov (cherry picked from commit 797709ebb18175fae2cff8b7f788019dd7c274a5) --- doc/rbd/rbd-persistent-write-back-cache.rst | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/doc/rbd/rbd-persistent-write-back-cache.rst b/doc/rbd/rbd-persistent-write-back-cache.rst index 2ac146d5f2b5..db91e0697f16 100644 --- a/doc/rbd/rbd-persistent-write-back-cache.rst +++ b/doc/rbd/rbd-persistent-write-back-cache.rst @@ -47,8 +47,8 @@ need to be enabled.:: rbd persistent cache mode = {cache-mode} rbd plugins = pwl_cache -Value of {cache-mode} can be ``rwl`` or ``ssd``. By default it is -``disabled`` +Value of {cache-mode} can be ``rwl``, ``ssd`` or ``disabled``. By default the +cache is disabled. Here are some cache configuration settings: @@ -56,10 +56,12 @@ Here are some cache configuration settings: have DAX enabled (see `DAX`_) when using ``rwl`` mode to avoid performance degradation. -- ``rbd_persistent_cache_size`` The cache size per image. +- ``rbd_persistent_cache_size`` The cache size per image. The minimum cache + size is 1 GB. - ``rbd_persistent_cache_log_periodic_stats`` This is a debug option. It is - used to emit periodic perf stats to the debug log. + used to emit periodic perf stats to the debug log if ``debug rbd pwl`` is + set to ``1`` or higher. The above configurations can be set per-host, per-pool, per-image etc. Eg, to set per-host, add the overrides to the appropriate `section`_ in the host's -- 2.47.3