From: Dmitriy Rabotyagov Date: Fri, 14 May 2021 07:19:21 +0000 (+0300) Subject: doc/rados/operations/stretch-mode: Adjust description of mon.e placement X-Git-Tag: v17.1.0~1041^2 X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=ef90c16239aa04aa257976ea61a67ee5ceecd8ce;p=ceph.git doc/rados/operations/stretch-mode: Adjust description of mon.e placement From current state of the documentation it is not clear about where in tree mon.e should be located. This may raise questions from operators[1] Also remove trailing whitespaces from doc. [1] https://lists.ceph.io/hyperkitty/list/ceph-users@ceph.io/thread/XWI5VNTMPA2JZEE7VCEQT4ACWVVKKOPQ/ Signed-off-by: Dmitriy Rabotyagov --- diff --git a/doc/rados/operations/stretch-mode.rst b/doc/rados/operations/stretch-mode.rst index a9113b09771..3233eae7b92 100644 --- a/doc/rados/operations/stretch-mode.rst +++ b/doc/rados/operations/stretch-mode.rst @@ -94,7 +94,7 @@ named ``site1`` and ``site2``:: } Finally, inject the CRUSH map to make the rule available to the cluster:: - + $ crushtool -c crush.map.txt -o crush2.map.bin $ ceph osd setcrushmap -i crush2.map.bin @@ -104,9 +104,13 @@ the instructions in `Changing Monitor Elections`_. .. _Changing Monitor elections: ../change-mon-elections And lastly, tell the cluster to enter stretch mode. Here, ``mon.e`` is the -tiebreaker and we are splitting across data centers :: +tiebreaker and we are splitting across data centers. ``mon.e`` should be also +set a datacenter, that will differ from ``site1`` and ``site2``. For this +purpose you can create another datacenter bucket named ```site3`` in your +CRUSH and place ``mon.e`` there :: - $ ceph mon enable_stretch_mode e stretch_rule data center + $ ceph mon set_location e datacenter=site3 + $ ceph mon enable_stretch_mode e stretch_rule datacenter When stretch mode is enabled, the OSDs wlll only take PGs active when they peer across data centers (or whatever other CRUSH bucket type @@ -132,7 +136,6 @@ restores min_size to its starting value (2) and requires both sites to peer, and stops requiring the always-alive site when peering (so that you can fail over to the other site, if necessary). - Stretch Mode Limitations ======================== As implied by the setup, stretch mode only handles 2 sites with OSDs. @@ -172,7 +175,7 @@ when the PGs are healthy. If this doesn't happen, or you want to force the cross-data-center peering early and are willing to risk data downtime (or have verified separately that all the PGs can peer, even if they aren't fully recovered), you can invoke :: - + $ ceph osd force_healthy_stretch_mode --yes-i-really-mean-it This command should not be necessary; it is included to deal with