On Tue, Jan 7, 2014 at 7:50 AM, Jon Bernard <jbern...@tuxion.com> wrote:
> Hello all, > > I would like to propose instance-level snapshots as a feature for > inclusion in Nova. An initial draft of the more official proposal is > here [1], blueprint is here [2]. > > In a nutshell, this feature will take the existing create-image > functionality a few steps further by providing the ability to take > a snapshot of a running instance that includes all of its attached > volumes. A coordinated snapshot of multiple volumes for backup > purposes. The snapshot operation should occur while the instance is in > a paused and quiesced state so that each volume snapshot is both > consistent within itself and with respect to its sibling snapshots. > > I still have some open questions on a few topics: > > * API changes, two different approaches come to mind: > > 1. Nova already has a command `createImage` for creating an image of an > existing instance. This command could be extended to take an > additional parameter `all-volumes` that signals the underlying code > to capture all attached volumes in addition to the root volume. The > semantic here is important, `createImage` is used to create > a template image stored in Glance for later reuse. If the primary > intent of this new feature is for backup only, then it may not be > wise to overlap the two operations in this way. On the other hand, > this approach would introduce the least amount of change to the > existing API, requiring only modification of an existing command > instead of the addition of an entirely new one. > > 2. If the feature's primary use is for backup purposes, then a new API > call may be a better approach, and leave `createImage` untouched. > This new call could be called `createBackup` and take as a parameter > the name of the instance. Although it introduces a new member to the > API reference, it would allow this feature to evolve without > introducing regressions in any existing calls. These two calls could > share code at some point in the future. > Note there already is a createBackup/create_backup API call implemented in the admin_actions extension (in V3 API it is being separated into its own extension https://review.openstack.org/#/c/62280/) It doesn't do the all volumes snapshot that you want though. There's a small window (basically end of icehouse) to make an incompatible change in the V3 API if that would be the best way to do it. Chris
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