Hello everyone,
I’m currently setting up my first Ceph mirror configuration and have a few questions regarding its behavior.
For example, I’m uncertain about how to force-promote an image on my DR cluster (site-b) during the synchronization process.
From what I’ve read in the documentation, in a disaster scenario occurring during synchronization, a force-promote operation promotes the last snapshot received by the DR cluster. However, as noted:
"Since this mode is not as fine-grained as journaling, the complete delta between two snapshots will need to be synced prior to use during a failover scenario. Any partially applied set of deltas will be rolled back at the moment of failover."
When I attempt to force-promote an image, I encounter the following error:
I’ve checked the snapshots on my DR cluster (site-b) and always see the latest snapshot of the image present there.
I have configured periodic snapshots to run every 3 minutes.
On the main cluster (site-a), I always retain the last 5 snapshots, while on the DR cluster (site-b), only the most recent snapshot is kept.
I assume that this latest snapshot is overwritten during the synchronization process
My main question is: How does Ceph handle promotion for an image when the data hasn’t been fully received on the DR cluster (site-b)?
Thank you!
Regards
I’m currently setting up my first Ceph mirror configuration and have a few questions regarding its behavior.
For example, I’m uncertain about how to force-promote an image on my DR cluster (site-b) during the synchronization process.
From what I’ve read in the documentation, in a disaster scenario occurring during synchronization, a force-promote operation promotes the last snapshot received by the DR cluster. However, as noted:
"Since this mode is not as fine-grained as journaling, the complete delta between two snapshots will need to be synced prior to use during a failover scenario. Any partially applied set of deltas will be rolled back at the moment of failover."
When I attempt to force-promote an image, I encounter the following error:
Code:
root@pve1-b:~# rbd mirror image promote ceph-pool/vm-103-disk-1 --force
2025-01-09T09:42:40.412+0100 7983d4e006c0 -1 librbd::mirror::snapshot::util: can_create_primary_snapshot: cannot rollback
2025-01-09T09:42:40.412+0100 7983d4e006c0 -1 librbd::mirror::snapshot::PromoteRequest: 0x7983b0001d40 send: cannot promote
2025-01-09T09:42:40.412+0100 7983d4e006c0 -1 librbd::mirror::PromoteRequest: 0x7983b401a810 handle_promote: failed to promote image: (22) Invalid argument
rbd: error promoting image to primary
2025-01-09T09:42:40.412+0100 7983d84f1780 -1 librbd::api::Mirror: image_promote: failed to promote imageI’ve checked the snapshots on my DR cluster (site-b) and always see the latest snapshot of the image present there.
I have configured periodic snapshots to run every 3 minutes.
On the main cluster (site-a), I always retain the last 5 snapshots, while on the DR cluster (site-b), only the most recent snapshot is kept.
I assume that this latest snapshot is overwritten during the synchronization process
My main question is: How does Ceph handle promotion for an image when the data hasn’t been fully received on the DR cluster (site-b)?
Thank you!
Regards