From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [RFC V9 1/4] domain snapshot terms Date: Thu, 18 Dec 2014 15:05:19 +0000 Message-ID: <1418915119.11882.79.camel@citrix.com> References: <1418711577-15449-1-git-send-email-cyliu@suse.com> <1418711577-15449-2-git-send-email-cyliu@suse.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1418711577-15449-2-git-send-email-cyliu@suse.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Chunyan Liu Cc: ian.jackson@eu.citrix.com, jfehlig@suse.com, wei.liu2@citrix.com, xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On Tue, 2014-12-16 at 14:32 +0800, Chunyan Liu wrote: > Changes to V8: > * add a document for domain snapshot related terms, they will be > referred in later documents. > > ===================================================================== > Terms > > * Active domain: domain created and started > > * Inactive domain: domain created but not started As Wei says I think you mean "defined" here, since created and started are (essentially) synonyms for some toolstacks. You'll probably want to define "defined" too for clarity. > > * Domain snapshot: > > Domain snapshot is a system checkpoint of a domain. It contains > the memory status at the checkpoint and the disk status. > > * Disk-only snapshot: > > Disk-only snapshot only keeps the status of disk, not saving > memory status. > > Contents of disks (whether a subset or all disks associated with > the domain) are saved at a given point of time, and can be restored > back to that state. On a running guest, a disk-only snapshot is > likely to be only crash-consistent rather than clean (that is, it > represents the state of the disk on a sudden power outage); on an > inactive guest, a disk-only snapshot is clean if the disks were > clean when the guest was last shut down. There is the possibility of doing clean snapshots if a guest agent is involved to quiesce the disks at the right moment (e.g. I believe qemu has such a thing, or at least I've seen talks about it being developed at conferences). Are you including this possibility or explicitly ruling it out of scope? > * Live Snapshot: > > Like live migration, it will increase size of the memory dump file, > but reducess downtime of the guest. > > * Internal Disk Snapshot > > File formats such as qcow2 track both the snapshot and changes > since the snapshot in a single file. > > * External Disk Snapshot > > The snapshot is one file, and the changes since the snapshot > are in another file.