qemu-img convert a qcow2 to a qcow2

[Marcus Sorensen <sh...@gmail.com>]

Anyone know why we do a convert from qcow2 to qcow2 when we crete a volume
or template? It seems slower than file copy, and it strips valuable
compression which could speed up deployments significantly. Our qcow2
templates are compressed to about 1/3 size of uncompressed, and since the
compression is read-only it doesn't really affect future write performance,
and gives a slight performance gain to reads since less is read.

createvolume.sh
qemu_img convert -f qcow2 -O qcow2

managesnapshot.sh
qemu_img convert -f qcow2 -O qcow2

createtmplt.sh
qemu_img convert -f qcow2 -O qcow2

I'd suggest if we already know it's qcow2, and we want to create a qcow2 to
copy the file. Objections?

Re: qemu-img convert a qcow2 to a qcow2

[Bryan Whitehead <dr...@megahappy.net>]

Well there we go. 'the more you know...'

On Fri, Dec 7, 2012 at 4:33 PM, Marcus Sorensen <sh...@gmail.com> wrote:

> There already is backing qcow2 support. But when cloudstack moves the
> template from secondary to primary storage to use as a backing file for all
> of your VMs, it does a convert. That strips any snapshots or compression
> that an uploader may have been counting on, and is overall slower than just
> copying the template.
>
> On Fri, Dec 7, 2012 at 4:51 PM, Bryan Whitehead <driver@megahappy.net
> >wrote:
>
> > ee backing qcow2 support instead of any kind of copying.
>

Re: qemu-img convert a qcow2 to a qcow2

[Marcus Sorensen <sh...@gmail.com>]

There already is backing qcow2 support. But when cloudstack moves the
template from secondary to primary storage to use as a backing file for all
of your VMs, it does a convert. That strips any snapshots or compression
that an uploader may have been counting on, and is overall slower than just
copying the template.

On Fri, Dec 7, 2012 at 4:51 PM, Bryan Whitehead <dr...@megahappy.net>wrote:

> ee backing qcow2 support instead of any kind of copying.

Re: qemu-img convert a qcow2 to a qcow2

[Bryan Whitehead <dr...@megahappy.net>]

I'd prefer to see backing qcow2 support instead of any kind of copying.


On Wed, Dec 5, 2012 at 1:29 PM, Edison Su <Ed...@citrix.com> wrote:

> If the source image has dependence on other images, then we should use
> "qemu-img convert ", otherwise, "cp" is enough.
>
> > -----Original Message-----
> > From: Marcus Sorensen [mailto:shadowsor@gmail.com]
> > Sent: Wednesday, December 05, 2012 1:01 PM
> > To: cloudstack-dev@incubator.apache.org
> > Subject: Re: qemu-img convert a qcow2 to a qcow2
> >
> > Eventually we'll probably want to support multiple versions, replacing
> one or
> > both of the formats with variables, but even then we'll probably just
> want to
> > copy if source format == destination format.
> >
> >
> > On Wed, Dec 5, 2012 at 1:51 PM, Rohit Yadav <ro...@citrix.com>
> > wrote:
> >
> > >
> > > On 05-Dec-2012, at 12:17 PM, Marcus Sorensen <sh...@gmail.com>
> > wrote:
> > >
> > > > Anyone know why we do a convert from qcow2 to qcow2 when we crete
> > a
> > > volume
> > > > or template? It seems slower than file copy, and it strips valuable
> > > > compression which could speed up deployments significantly. Our
> > > > qcow2 templates are compressed to about 1/3 size of uncompressed,
> > > > and since the compression is read-only it doesn't really affect
> > > > future write
> > > performance,
> > > > and gives a slight performance gain to reads since less is read.
> > > >
> > > > createvolume.sh
> > > > qemu_img convert -f qcow2 -O qcow2
> > > >
> > > > managesnapshot.sh
> > > > qemu_img convert -f qcow2 -O qcow2
> > > >
> > > > createtmplt.sh
> > > > qemu_img convert -f qcow2 -O qcow2
> > > >
> > > > I'd suggest if we already know it's qcow2, and we want to create a
> > > > qcow2
> > > to
> > > > copy the file. Objections?
> > >
> > >
> > > I don't know why we do that, but what the command is saying is that we
> > > want to convert an input image from qcow2 to keeping the same output
> > > format, -O qcow2 But yes, if the input format is already qcow2 and
> > > output is qcow2 we can just copy the file. Edison?
> > >
> > > Regards.
>

RE: qemu-img convert a qcow2 to a qcow2

[Edison Su <Ed...@citrix.com>]

If the source image has dependence on other images, then we should use "qemu-img convert ", otherwise, "cp" is enough. 

> -----Original Message-----
> From: Marcus Sorensen [mailto:shadowsor@gmail.com]
> Sent: Wednesday, December 05, 2012 1:01 PM
> To: cloudstack-dev@incubator.apache.org
> Subject: Re: qemu-img convert a qcow2 to a qcow2
> 
> Eventually we'll probably want to support multiple versions, replacing one or
> both of the formats with variables, but even then we'll probably just want to
> copy if source format == destination format.
> 
> 
> On Wed, Dec 5, 2012 at 1:51 PM, Rohit Yadav <ro...@citrix.com>
> wrote:
> 
> >
> > On 05-Dec-2012, at 12:17 PM, Marcus Sorensen <sh...@gmail.com>
> wrote:
> >
> > > Anyone know why we do a convert from qcow2 to qcow2 when we crete
> a
> > volume
> > > or template? It seems slower than file copy, and it strips valuable
> > > compression which could speed up deployments significantly. Our
> > > qcow2 templates are compressed to about 1/3 size of uncompressed,
> > > and since the compression is read-only it doesn't really affect
> > > future write
> > performance,
> > > and gives a slight performance gain to reads since less is read.
> > >
> > > createvolume.sh
> > > qemu_img convert -f qcow2 -O qcow2
> > >
> > > managesnapshot.sh
> > > qemu_img convert -f qcow2 -O qcow2
> > >
> > > createtmplt.sh
> > > qemu_img convert -f qcow2 -O qcow2
> > >
> > > I'd suggest if we already know it's qcow2, and we want to create a
> > > qcow2
> > to
> > > copy the file. Objections?
> >
> >
> > I don't know why we do that, but what the command is saying is that we
> > want to convert an input image from qcow2 to keeping the same output
> > format, -O qcow2 But yes, if the input format is already qcow2 and
> > output is qcow2 we can just copy the file. Edison?
> >
> > Regards.

Re: qemu-img convert a qcow2 to a qcow2

[Marcus Sorensen <sh...@gmail.com>]

Eventually we'll probably want to support multiple versions, replacing one
or both of the formats with variables, but even then we'll probably just
want to copy if source format == destination format.


On Wed, Dec 5, 2012 at 1:51 PM, Rohit Yadav <ro...@citrix.com> wrote:

>
> On 05-Dec-2012, at 12:17 PM, Marcus Sorensen <sh...@gmail.com> wrote:
>
> > Anyone know why we do a convert from qcow2 to qcow2 when we crete a
> volume
> > or template? It seems slower than file copy, and it strips valuable
> > compression which could speed up deployments significantly. Our qcow2
> > templates are compressed to about 1/3 size of uncompressed, and since the
> > compression is read-only it doesn't really affect future write
> performance,
> > and gives a slight performance gain to reads since less is read.
> >
> > createvolume.sh
> > qemu_img convert -f qcow2 -O qcow2
> >
> > managesnapshot.sh
> > qemu_img convert -f qcow2 -O qcow2
> >
> > createtmplt.sh
> > qemu_img convert -f qcow2 -O qcow2
> >
> > I'd suggest if we already know it's qcow2, and we want to create a qcow2
> to
> > copy the file. Objections?
>
>
> I don't know why we do that, but what the command is saying is that we
> want to convert an input image from qcow2 to keeping the same output
> format, -O qcow2
> But yes, if the input format is already qcow2 and output is qcow2 we can
> just copy the file. Edison?
>
> Regards.

Re: qemu-img convert a qcow2 to a qcow2

[Rohit Yadav <ro...@citrix.com>]

On 05-Dec-2012, at 12:17 PM, Marcus Sorensen <sh...@gmail.com> wrote:

> Anyone know why we do a convert from qcow2 to qcow2 when we crete a volume
> or template? It seems slower than file copy, and it strips valuable
> compression which could speed up deployments significantly. Our qcow2
> templates are compressed to about 1/3 size of uncompressed, and since the
> compression is read-only it doesn't really affect future write performance,
> and gives a slight performance gain to reads since less is read.
> 
> createvolume.sh
> qemu_img convert -f qcow2 -O qcow2
> 
> managesnapshot.sh
> qemu_img convert -f qcow2 -O qcow2
> 
> createtmplt.sh
> qemu_img convert -f qcow2 -O qcow2
> 
> I'd suggest if we already know it's qcow2, and we want to create a qcow2 to
> copy the file. Objections?


I don't know why we do that, but what the command is saying is that we want to convert an input image from qcow2 to keeping the same output format, -O qcow2
But yes, if the input format is already qcow2 and output is qcow2 we can just copy the file. Edison?

Regards.