Chengen, Now the changes review notes:
This patch is concerning for a couple of reasons, if I understand correctly: 1) behavior changes that are potentially impactful to the storage backend; 2) new requirements for the deployment configuration that might seriously impact the deployment. In order to proceed, could you please discuss/confirm these with Ed (hopem), Dan (hillpd), and if they both agree, get an ACK from James Page (james-page), and record their feedback here? I'll mark the bug task as Incomplete for now. Thanks! Mauricio Details: 1) The behavior change (flatten dependent images on volume removal) seems to introduce O(N) load in the cluster in storage size/consumption _and_ CPU load, as each dependent image will be flattened thus the data from the volume being removed will be copied into _each one_, which multiplies the storage consumption with a single delete operation. Without the patch, this would not happen, as the operation would fail. @ https://docs.ceph.com/en/latest/rbd/rbd-snapshot/#flattening-a-cloned- image When you remove the reference to the parent snapshot from the clone, you effectively “flatten” the clone by copying the data stored in the snapshot to the clone. The time it takes to flatten a clone increases with the size of the snapshot. @ https://docs.ceph.com/en/latest/man/8/rbd/ If the image is a clone, copy all shared blocks from the parent snapshot [...] @ patch ++ cfg.IntOpt('rbd_concurrent_flatten_operations', default=3, min=0, ++ help='Number of flatten operations that will run ' ++ 'concurrently on this volume service.') 2) The patch doc/note says that the deployments now must enable deletion options. It seems potentially problematic if this is missed, specially with auto upgrades, as, if such option is not enabled, this could eventually consume a lot of storage, and not be removed until that is noticed (when it might be too late) ? ++ Cinder now uses the RBD trash functionality to handle some volume deletions. ++ Therefore, deployments must either a) enable scheduled RBD trash purging on ++ the RBD backend or b) enable the Cinder RBD driver's enable_deferred_deletion ++ option to have Cinder purge the RBD trash. ** Changed in: cinder (Ubuntu Jammy) Status: In Progress => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1969643 Title: RBD: Unable to delete a volume which has snapshot/volume children To manage notifications about this bug go to: https://bugs.launchpad.net/cinder/+bug/1969643/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
