On Mon, Apr 25, 2022 at 12:57 AM Eneko Lacunza <elacunza@xxxxxxxxx> wrote: > > Hi all, > > We're looking to deploy a stretch cluster for a 2-CPD deployment. I have > read the following docs: > https://docs.ceph.com/en/latest/rados/operations/stretch-mode/#stretch-clusters > > I have some questions: > > - Can we have multiple pools in a stretch cluster? Yes. > - Can we have multiple different crush rules in a stretch cluster? I'm > asking this because the command for stretch mode activation asks for a > rule... Right, so what happens there is any pool with a default rule gets switched to the specified CRUSH rule. That doesn't stop you from changing the rule after engaging stretch mode, or giving it a non-default rule ahead of time. You just have to be careful to make sure it satisfies the stretch mode rules about placing across data centers. > We want to have different purpose pools on this Ceph cluster: > > - Important VM disks, with 2 copies in each DC (SSD class) > - Ephemeral VM disks, with just 2 copies overall (SSD class) > - Backup data in just one DC (HDD class). > > Objective of the 2-DC deployment is disaster recovery, HA isn't > required, but I'll take it if deployment is reasonable :-) . I'm leery of this for the reasons described in the docs — if you don't have 2 replicas per site, you lose data availability every time an OSD goes down for any reason (or else you have a window while recovery happens where the data is not physically available in both sites, which rather negates the purpose). -Greg > > Alternative would be a size=4/min=3 pool for important VM disks in a > no-strech cluster... > > Thanks > > Eneko Lacunza > Zuzendari teknikoa | Director técnico > Binovo IT Human Project > > Tel. +34 943 569 206 |https://www.binovo.es > Astigarragako Bidea, 2 - 2º izda. Oficina 10-11, 20180 Oiartzun > > https://www.youtube.com/user/CANALBINOVO > https://www.linkedin.com/company/37269706/ > _______________________________________________ > ceph-users mailing list -- ceph-users@xxxxxxx > To unsubscribe send an email to ceph-users-leave@xxxxxxx _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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