Re: [Gluster-devel] reflink support for glusterfs and gluster-block using it for taking snapshots

[Pranith Kumar Karampuri]

On Thu, Nov 9, 2017 at 8:26 PM, Niels de Vos  wrote:

> On Tue, Nov 07, 2017 at 05:59:32PM +0530, Pranith Kumar Karampuri wrote:
> > On Tue, Nov 7, 2017 at 5:16 PM, Niels de Vos  wrote:
> >
> > > On Tue, Nov 07, 2017 at 07:43:17AM +0530, Pranith Kumar Karampuri
> wrote:
> > > > hi,
> > > >  I just created a github issue for reflink support
> > > > (#349) in
> glusterfs. We
> > > > are intending to use this feature to do block snapshots in
> gluster-block.
> > > >
> > > > Please let us know your comments on the github issue. I have added
> the
> > > > changes we may need for xlators I know a little bit about. Please
> help in
> > > > identifying gaps in implementing this FOP.
> > >
> > > For gluster-block it may be easier to have snapshot support in
> > > tcmu-runner instead? The qcow2 format would be ideal, and is in use by
> > > different Virtual Machine approaches running on Gluster already. There
> > > even is an upstream issue open for it:
> > >   https://github.com/open-iscsi/tcmu-runner/issues/32
> > >
> > > Contributing towards this might be quicker than implementing file
> > > snapshot support in Gluster?
> > >
> >
> > We tried that route by talking Fam Zheng, but the solution won't be
> > delivered in the timelines we are looking for.
> > So we went with this approach.
>
> Ok, I am not sure if adding support for reflink in Gluster has an
> immediate benefit. It surely would be a great feature to have, but I do
> not know if it will land in enterprise kernels soon.
>

https://github.com/gluster/glusterfs/issues/377 should address this concern
until reflink becomes mainstream.


>
> That said, I opened a GitHub issue to get reliable snapshot support in
> gluster-block. It describes an idea of the interface that could be
> implemented now already, without relying on reflink.
>
>   https://github.com/gluster/gluster-block/issues/42
>
> Obviously there is a need to sync/freeze data through tcmu-runner. This
> might require implementing a fsfreeze(8) like command in targetcli and
> tcmu-runner.
>
> Comments most welcome!
> Niels
>



-- 
Pranith
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Re: [Gluster-devel] reflink support for glusterfs and gluster-block using it for taking snapshots

[Niels de Vos]

On Tue, Nov 07, 2017 at 05:59:32PM +0530, Pranith Kumar Karampuri wrote:
> On Tue, Nov 7, 2017 at 5:16 PM, Niels de Vos  wrote:
> 
> > On Tue, Nov 07, 2017 at 07:43:17AM +0530, Pranith Kumar Karampuri wrote:
> > > hi,
> > >  I just created a github issue for reflink support
> > > (#349) in glusterfs. We
> > > are intending to use this feature to do block snapshots in gluster-block.
> > >
> > > Please let us know your comments on the github issue. I have added the
> > > changes we may need for xlators I know a little bit about. Please help in
> > > identifying gaps in implementing this FOP.
> >
> > For gluster-block it may be easier to have snapshot support in
> > tcmu-runner instead? The qcow2 format would be ideal, and is in use by
> > different Virtual Machine approaches running on Gluster already. There
> > even is an upstream issue open for it:
> >   https://github.com/open-iscsi/tcmu-runner/issues/32
> >
> > Contributing towards this might be quicker than implementing file
> > snapshot support in Gluster?
> >
> 
> We tried that route by talking Fam Zheng, but the solution won't be
> delivered in the timelines we are looking for.
> So we went with this approach.

Ok, I am not sure if adding support for reflink in Gluster has an
immediate benefit. It surely would be a great feature to have, but I do
not know if it will land in enterprise kernels soon.

That said, I opened a GitHub issue to get reliable snapshot support in
gluster-block. It describes an idea of the interface that could be
implemented now already, without relying on reflink.

  https://github.com/gluster/gluster-block/issues/42

Obviously there is a need to sync/freeze data through tcmu-runner. This
might require implementing a fsfreeze(8) like command in targetcli and
tcmu-runner.

Comments most welcome!
Niels
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Re: [Gluster-devel] reflink support for glusterfs and gluster-block using it for taking snapshots

[Pranith Kumar Karampuri]

On Tue, Nov 7, 2017 at 5:16 PM, Niels de Vos  wrote:

> On Tue, Nov 07, 2017 at 07:43:17AM +0530, Pranith Kumar Karampuri wrote:
> > hi,
> >  I just created a github issue for reflink support
> > (#349) in glusterfs. We
> > are intending to use this feature to do block snapshots in gluster-block.
> >
> > Please let us know your comments on the github issue. I have added the
> > changes we may need for xlators I know a little bit about. Please help in
> > identifying gaps in implementing this FOP.
>
> For gluster-block it may be easier to have snapshot support in
> tcmu-runner instead? The qcow2 format would be ideal, and is in use by
> different Virtual Machine approaches running on Gluster already. There
> even is an upstream issue open for it:
>   https://github.com/open-iscsi/tcmu-runner/issues/32
>
> Contributing towards this might be quicker than implementing file
> snapshot support in Gluster?
>

We tried that route by talking Fam Zheng, but the solution won't be
delivered in the timelines we are looking for.
So we went with this approach.


>
> Niels
>



-- 
Pranith
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Re: [Gluster-devel] reflink support for glusterfs and gluster-block using it for taking snapshots

[Niels de Vos]

On Tue, Nov 07, 2017 at 07:43:17AM +0530, Pranith Kumar Karampuri wrote:
> hi,
>  I just created a github issue for reflink support
> (#349) in glusterfs. We
> are intending to use this feature to do block snapshots in gluster-block.
> 
> Please let us know your comments on the github issue. I have added the
> changes we may need for xlators I know a little bit about. Please help in
> identifying gaps in implementing this FOP.

For gluster-block it may be easier to have snapshot support in
tcmu-runner instead? The qcow2 format would be ideal, and is in use by
different Virtual Machine approaches running on Gluster already. There
even is an upstream issue open for it:
  https://github.com/open-iscsi/tcmu-runner/issues/32

Contributing towards this might be quicker than implementing file
snapshot support in Gluster?

Niels


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Re: [Gluster-devel] reflink support for glusterfs and gluster-block using it for taking snapshots

[Prasanna Kalever]

On Tue, Nov 7, 2017 at 7:43 AM, Pranith Kumar Karampuri
 wrote:
> hi,
>  I just created a github issue for reflink support(#349) in glusterfs.
> We are intending to use this feature to do block snapshots in gluster-block.
>
> Please let us know your comments on the github issue. I have added the
> changes we may need for xlators I know a little bit about. Please help in
> identifying gaps in implementing this FOP.

Pranith,

You might be interested in taking a look at an approach taken earlier
to support snapshots using xfs reflink feature.

Patch with working code:  https://review.gluster.org/#/c/13979/
Spec: 
https://github.com/gluster/glusterfs-specs/blob/master/under_review/reflink-based-fsnap.md

Note: It was more than one and a half years old stuff (April 2016), so
expect a rebase :-)

Thanks,
--
Prasanna

>
> --
> Pranith
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[Gluster-devel] reflink support for glusterfs and gluster-block using it for taking snapshots

[Pranith Kumar Karampuri]

hi,
 I just created a github issue for reflink support
(#349) in glusterfs. We
are intending to use this feature to do block snapshots in gluster-block.

Please let us know your comments on the github issue. I have added the
changes we may need for xlators I know a little bit about. Please help in
identifying gaps in implementing this FOP.

-- 
Pranith
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