From 99af6a2caffe1247e42e983b0fb4921d0a5df429 Mon Sep 17 00:00:00 2001 From: Zac Dover Date: Tue, 15 Nov 2022 10:30:34 +1000 Subject: [PATCH] doc/rados: reword part of cache-tiering.rst Reword part of cache-tiering.rst to make the English language added in https://github.com/ceph/ceph/pull/48861 more elegant. Signed-off-by: Zac Dover (cherry picked from commit 24ec058839a897270838473d1bc14c2eb19ee24e) --- doc/rados/operations/cache-tiering.rst | 28 +++++++++++++++----------- 1 file changed, 16 insertions(+), 12 deletions(-) diff --git a/doc/rados/operations/cache-tiering.rst b/doc/rados/operations/cache-tiering.rst index 00a3f37f93715..a9e7984d45dc6 100644 --- a/doc/rados/operations/cache-tiering.rst +++ b/doc/rados/operations/cache-tiering.rst @@ -45,18 +45,22 @@ and the backing storage tier automatically. However, admins have the ability to configure how this migration takes place by setting the ``cache-mode``. There are two main scenarios: -- **writeback** mode: When admins configure tiers with ``writeback`` mode, Ceph - clients write data to the base tier and receive an ACK from it. Then the cache - tiering agent compares ``osd_tier_default_cache_min_write_recency_for_promote``, - that means if the data is written over given times at a interval, it will - be promoted to the cache tier. When Ceph clients need data that resides in - the base tier, the cache tier will proxy read the data from the base tier - and return to the client. Meanwhile, as same as write does, the cache tiering - agent will decide whether migrating the data to the cache tier based on - ``osd_tier_default_cache_min_read_recency_for_promote``. After the data - is promoted to from the base tier, the Ceph client can perform I/O using - the cache tier, until the data becomes inactive. This is ideal for mutable - data (e.g., photo/video editing, transactional data, etc.). +- **writeback** mode: If the base tier and the cache tier are configured in + ``writeback`` mode, Ceph clients receive an ACK from the base tier every time + they write data to it. Then the cache tiering agent determines whether + ``osd_tier_default_cache_min_write_recency_for_promote`` has been set. If it + has been set and the data has been written more than a specified number of + times per interval, the data is promoted to the cache tier. + + When Ceph clients need access to data stored in the base tier, the cache + tiering agent reads the data from the base tier and returns it to the client. + While data is being read from the base tier, the cache tiering agent consults + the value of ``osd_tier_default_cache_min_read_recency_for_promote`` and + decides whether to promote that data from the base tier to the cache tier. + When data has been promoted from the base tier to the cache tier, the Ceph + client is able to perform I/O operations on it using the cache tier. This is + well-suited for mutable data (for example, photo/video editing, transactional + data). - **readproxy** mode: This mode will use any objects that already exist in the cache tier, but if an object is not present in the -- 2.39.5