doc/rados/operations: Clarify stretch mode vs device class

Signed-off-by: Anthony D'Atri <[email protected]>

Author: anthonyeleven

doc/rados/operations/stretch-mode.rst

@@ -335,16 +335,16 @@ a CRUSH rule is given above.
 
 Because stretch mode runs with ``min_size`` set to ``1`` (or, more directly,
 ``min_size 1``), we recommend enabling stretch mode only when using OSDs on
-SSDs (including NVMe OSDs). Hybrid HDD+SDD or HDD-only OSDs are not recommended
+SSDs. Hybrid HDD+SSD or HDD-only OSDs are not recommended
 due to the long time it takes for them to recover after connectivity between
 data centers has been restored. This reduces the potential for data loss.
 
-.. warning:: Device class is currently not supported in stretch mode.
-   For example, the following rule containing ``device class`` will not work::
+.. warning:: CRUSH rules that specify a device class are not supported in stretch mode.
+   For example, the following rule specifying the ``ssd`` device class will not work::
 
       rule stretch_replicated_rule {
                  id 2
-                 type replicated class hdd
+                 type replicated class ssd
                  step take default
                  step choose firstn 0 type datacenter
                  step chooseleaf firstn 2 type host
@@ -353,7 +353,7 @@ data centers has been restored. This reduces the potential for data loss.
 
 In the future, stretch mode could support erasure-coded pools,
 enable deployments across multiple data centers,
-and accommodate various device classes.
+and accommodate multiple CRUSH device classes.
 
 Other commands
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