[ovirt-devel] Snapshots & clone support from datastore

[Deepak Jagtap]

Hi Allon,


I am trying to leverage snapshot  capability of underlying filesystem.

As per my understanding current snapshot works like this:

Base Image(raw)--->snap1(qcow)->snap2(qcow), i.e after each snapshot vm starts writing on newly created qcow image.

So in this case vm is going to do all new writes on snap2(qcow) voulme and will redirect read IOs to snap1 & Base image as required.


But in my case snapshots created by the filesystem are read only and it's in raw format.

As a result after creating snapshot vm disk configuration won't change after taking snapshot but will continue doing writes on same base image.

So snapshots will look like this:

Base Image(raw)--->snap1(raw)->snap2(raw)

Base Image will always remain writable, while the snapshots will remain read only raw format.


Just wanted to confirm is this configurable so that vm continues  referring base image after the snapshot instead of newly created qcow image?


Thanks & Regards,

Deepak






________________________________
From: Allon Mureinik <amureini at redhat.com>
Sent: Tuesday, June 20, 2017 7:59:03 PM
To: Deepak Jagtap
Cc: devel at ovirt.org
Subject: Re: [ovirt-devel] Snapshots & clone support from datastore

Not sure I understand the question. Could you give an example of what you mean perhpas?

On Tue, Jun 20, 2017 at 10:01 PM, Deepak Jagtap <deepak.jagtap at maxta.com<mailto:deepak.jagtap at maxta.com>> wrote:

Hi Allon,


After going through current vdsm code base, noticed that after taking a snapshot vm starts referring the newly created qcow image/volume.

For internal snapshots which are not qcow  is it configurable somehow so that vm continues doing writes to same base image?


Thanks & Regards,

Deepak

________________________________
From: Deepak Jagtap
Sent: Tuesday, June 6, 2017 3:37:03 PM
To: Allon Mureinik
Cc: devel at ovirt.org<mailto:devel at ovirt.org>
Subject: Re: [ovirt-devel] Snapshots & clone support from datastore


Thanks Allon!


Best Regards,

Deepak

________________________________
From: Allon Mureinik <amureini at redhat.com<mailto:amureini at redhat.com>>
Sent: Tuesday, June 6, 2017 2:43:17 PM
To: Deepak Jagtap
Cc: devel at ovirt.org<mailto:devel at ovirt.org>
Subject: Re: [ovirt-devel] Snapshots & clone support from datastore

Unfortunately, there's no such integration point at the moment.

On Tue, Jun 6, 2017 at 5:57 AM, Deepak Jagtap <deepak.jagtap at maxta.com<mailto:deepak.jagtap at maxta.com>> wrote:

Hey Guys,


I am newbie to ovirt, and wanted to confirm whats the best way to leverage snapshot, clone features

provided by the datastore filesystem.

I have a btrfs datastore exported and wanted use btrfs snapshots for vm snapshot & clones.

Does ovirt offers any hooks/APIs so that image snapshots are created by the filesystem?


Thanks & Regards,

Deepak



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