Never ever use osd pool default min size = 1 this will break your neck and does not make sense really. :-) On Mon, Jul 10, 2023 at 7:33 PM Dan van der Ster <dan.vanderster@clyso.com> wrote:
Hi Jan,
On Sun, Jul 9, 2023 at 11:17 PM Jan Marek <jmarek@jcu.cz> wrote:
Hello,
I have a cluster, which have this configuration:
osd pool default size = 3 osd pool default min size = 1
Don't use min_size = 1 during regular stable operations. Instead, use min_size = 2 to ensure data safety, and then you can set the pool to min_size = 1 manually in the case of an emergency. (E.g. in case the 2 copies fail and will not be recoverable).
I have 5 monitor nodes and 7 OSD nodes.
3 monitors is probably enough. Put 2 in the same DC with 2 replicas, and the other in the DC with 1 replica.
I have changed a crush map to divide ceph cluster to two datacenters - in the first one will be a part of cluster with 2 copies of data and in the second one will be part of cluster with one copy - only emergency.
I still have this cluster in one
This cluster have a 1 PiB of raw data capacity, thus it is very expensive add a further 300TB capacity to have 2+2 data redundancy.
Will it works?
If I turn off the 1/3 location, will it be operational?
Yes the PGs should be active and accept IO. But the cluster will be degraded, it cannot stay in this state permanently. (You will need to recover the 3rd replica or change the crush map).
I believe, it is a better choose, it will. And what if "die" 2/3 location?
with min_size = 2, the PG wil be inactive. but the data will be safe. If this happens, then set min_size=1 to activate the PGs. Mon will not have quorum though -- you need a plan for that. And also plan where you put your MDSs.
-- dan
______________________________________________________ Clyso GmbH | Ceph Support and Consulting | https://www.clyso.com
On this cluster is pool with cephfs - this is a main part of CEPH.
Many thanks for your notices.
Sincerely Jan Marek -- Ing. Jan Marek University of South Bohemia Academic Computer Centre Phone: +420389032080 http://www.gnu.org/philosophy/no-word-attachments.cs.html _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
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