Hi, I just deployed a test cluster to try that out, too. I only deployed three MONs, but this should also apply.

I tried to create the third datacenter and put the tiebreaker there but got the following error: ---------------------------------------------------- root@ceph-node-01:/home/clouduser# ceph mon enable_stretch_mode ceph-node-05 stretch_rule datacenter Error EINVAL: there are 3datacenter's in the cluster but stretch mode currently only works with 2!

You don't create a third datacenter within the osd tree, you just tell ceph that your tie-breaker is in a different dc. For me it worked, I have two DCs and put the third (tie-breaker) into (virtual) dc3: pacific1:~ # ceph mon set_location pacific3 datacenter=dc3 pacific1:~ # ceph mon enable_stretch_mode pacific3 stretch_rule datacenter This automatically triggered pool size 4 and distributed the PGs evenly across both DCs. Regards, Eugen Zitat von Felix O <hostorig@gmail.com>:

Hello,

I'm trying to deploy my test ceph cluster and enable stretch mode ( https://docs.ceph.com/en/latest/rados/operations/stretch-mode/). My problem is enabling the stretch mode. ---------------------------------------------------- $ ceph mon enable_stretch_mode ceph-node-05 stretch_rule datacenter Error EINVAL: Could not find location entry for datacenter on monitor ceph-node-05 ---------------------------------------------------- ceph-node-5 is the tiebreaker monitor

I tried to create the third datacenter and put the tiebreaker there but got the following error: ---------------------------------------------------- root@ceph-node-01:/home/clouduser# ceph mon enable_stretch_mode ceph-node-05 stretch_rule datacenter Error EINVAL: there are 3datacenter's in the cluster but stretch mode currently only works with 2! ---------------------------------------------------- An additional info: ---------------------------------------------------- Setup method: cephadm (https://docs.ceph.com/en/latest/cephadm/install/)

# ceph osd tree ID CLASS WEIGHT TYPE NAME STATUS REWEIGHT PRI-AFF -1 0.03998 root default -11 0.01999 datacenter site1 -5 0.00999 host ceph-node-01 0 hdd 0.00999 osd.0 up 1.00000 1.00000 -3 0.00999 host ceph-node-02 1 hdd 0.00999 osd.1 up 1.00000 1.00000 -12 0.01999 datacenter site2 -9 0.00999 host ceph-node-03 3 hdd 0.00999 osd.3 up 1.00000 1.00000 -7 0.00999 host ceph-node-04 2 hdd 0.00999 osd.2 up 1.00000 1.00000

stretch_rule is added to the crush

# ceph mon set_location ceph-node-01 datacenter=site1 # ceph mon set_location ceph-node-02 datacenter=site1 # ceph mon set_location ceph-node-03 datacenter=site2 # ceph mon set_location ceph-node-04 datacenter=site2

# ceph versions { "mon": { "ceph version 16.2.1 (afb9061ab4117f798c858c741efa6390e48ccf10) pacific (stable)": 5 }, "mgr": { "ceph version 16.2.1 (afb9061ab4117f798c858c741efa6390e48ccf10) pacific (stable)": 2 }, "osd": { "ceph version 16.2.1 (afb9061ab4117f798c858c741efa6390e48ccf10) pacific (stable)": 4 }, "mds": {}, "overall": { "ceph version 16.2.1 (afb9061ab4117f798c858c741efa6390e48ccf10) pacific (stable)": 11 } }

Thank you for your support.

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