From a26958ace669cf15cb5f2287e3bf9fee35909e17 Mon Sep 17 00:00:00 2001 From: Anthony D'Atri Date: Sun, 2 Mar 2025 10:43:18 -0500 Subject: [PATCH] doc/rados/operations: Clarify stretch mode vs device class Signed-off-by: Anthony D'Atri (cherry picked from commit 75be0272e8469ed214302b8f354bed675cdcaed6) --- doc/rados/operations/stretch-mode.rst | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/doc/rados/operations/stretch-mode.rst b/doc/rados/operations/stretch-mode.rst index 37c1de14b838c..b999f18942144 100644 --- a/doc/rados/operations/stretch-mode.rst +++ b/doc/rados/operations/stretch-mode.rst @@ -256,16 +256,16 @@ 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 @@ -274,7 +274,7 @@ 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 ============== -- 2.39.5