doc/start/os-recommendations: updates

Signed-off-by: Sage Weil <sage@redhat.com>

diff --git a/doc/start/os-recommendations.rst b/doc/start/os-recommendations.rst
index 1aeb42dca04cddb49f593d62c1fc56153784fba6..3aea814f5b980f71f69cd7f0ec92a9d738d45f90 100644 (file)
--- a/doc/start/os-recommendations.rst
+++ b/doc/start/os-recommendations.rst
@@ -13,9 +13,10 @@ Linux Kernel
 
 - **Ceph Kernel Client**
 
-  If you are using the kernel client, the general advice is to *track* "stable"
-  or "longterm maintenance" kernel series provided by either http://kernel.org
-  or your distribution on the kernel client machines.
+  If you are using the kernel client to map RBD block devices or mount
+  CephFS, the general advice is to use a "stable" or "longterm
+  maintenance" kernel series provided by either http://kernel.org or
+  your Linux distribution on any client hosts.
 
   For RBD, if you choose to *track* long-term kernels, we currently recommend
   4.x-based "longterm maintenance" kernel series:
@@ -23,19 +24,12 @@ Linux Kernel
   - 4.9.z
   - 4.4.z
 
-  These are considered pretty old, but if you must:
-
-  - 3.16.z
-  - 3.10.z
-
   For CephFS, see `CephFS best practices`_ for kernel version guidance.
 
-  Older kernel client versions may not support your `CRUSH tunables`_ profile.
-
-- **B-tree File System (Btrfs)**
+  Older kernel client versions may not support your `CRUSH tunables`_ profile
+  or other newer features of the Ceph cluster, requiring the storage cluster
+  to be configured with those features disabled.
 
-  We recommand *against* using ``btrfs`` with Ceph.  However, if you
-  insist on using ``btrfs``, we recommend using a recent Linux kernel.
 
 Platforms
 =========
@@ -67,8 +61,8 @@ Luminous (12.2.z)
 +----------+----------+--------------------+--------------+---------+------------+
 
 
-Infernalis (9.2.z) and Jewel (10.2.z)
--------------------------------------
+Jewel (10.2.z)
+--------------
 
 +----------+----------+--------------------+--------------+---------+------------+
 | Distro   | Release  | Code Name          | Kernel       | Notes   | Testing    | 
@@ -84,8 +78,8 @@ Infernalis (9.2.z) and Jewel (10.2.z)
 | Ubuntu   | 14.04    | Trusty Tahr        | linux-3.13.0 |         | B, I, C    |
 +----------+----------+--------------------+--------------+---------+------------+
 
-Hammer (0.94)
--------------
+Hammer (0.94.z)
+---------------
 
 +----------+----------+--------------------+--------------+---------+------------+
 | Distro   | Release  | Code Name          | Kernel       | Notes   | Testing    | 
@@ -101,8 +95,8 @@ Hammer (0.94)
 | Ubuntu   | 14.04    | Trusty Tahr        | linux-3.13.0 |         | B, I, C    |
 +----------+----------+--------------------+--------------+---------+------------+
 
-Firefly (0.80)
---------------
+Firefly (0.80.z)
+----------------
 
 +----------+----------+--------------------+--------------+---------+------------+
 | Distro   | Release  | Code Name          | Kernel       | Notes   | Testing    |