Libguestfs - Sep 2014 - Re: Why libguestfs guest exist exceptionally?

On Mon, Sep 29, 2014 at 1:14 AM, Richard W.M. Jones <rjones@redhat.com>
wrote:
> On Mon, Sep 29, 2014 at 12:55:04AM +0800, Zhi Yong Wu wrote:
>> On Mon, Sep 29, 2014 at 12:36 AM, Richard W.M. Jones
<rjones@redhat.com> wrote:
>> > On Sun, Sep 28, 2014 at 11:43:17PM +0800, Zhi Yong Wu wrote:
>> >> Yeah, but why did it happen when i directly issue guest VM via
above command?
>> >
>> > OK I see.  When libguestfs runs qemu-kvm, it sets up a TCP socket
>> > first [on RHEL 5 -- it works differently upstream].  Without the
>> > socket existing (and sending commands etc), the qemu-kvm command
on
>> > its own won't work.
>> I got it, thanks.
>>
>> By the way, i found that virt-xxx usually has very poor performance on
>> my box. e.g. virt-filesystems will return the result in 30s,
>> virt-resize will need 30 minutes to complete resizing one disk. Every
>> virt-xxx need to start one QEMU guest at first every time it is
>> issued, so this takes too long time to run. I am trying to find out
>> some ways to improve its perf.
>
> A good place to start is:
>
>   http://libguestfs.org/guestfs-performance.1.html
>
> Are you running this inside a VM?
Yes, I am trying to run it in Xen Domain0. I thought that we can use
Domain0 as a public libguestfs VM, This will avoid starting a new
guest for virt-xxx every time, But Domain0 has no corresponding qemu
task. So this way isn't available.
Now, i am considering if we can run private VM for libguestfs which
will keep running forever and if it will bring more trouble.
>
> Rich.
>
> --
> Richard Jones, Virtualization Group, Red Hat
http://people.redhat.com/~rjones
> Read my programming and virtualization blog: http://rwmj.wordpress.com
> virt-df lists disk usage of guests without needing to install any
> software inside the virtual machine.  Supports Linux and Windows.
> http://people.redhat.com/~rjones/virt-df/


-- 
Regards,

Zhi Yong Wu

On Mon, Sep 29, 2014 at 01:22:19AM +0800, Zhi Yong Wu
wrote:
> Yes, I am trying to run it in Xen Domain0. I thought that we can use
> Domain0 as a public libguestfs VM, This will avoid starting a new
> guest for virt-xxx every time, But Domain0 has no corresponding qemu
> task. So this way isn't available.
> Now, i am considering if we can run private VM for libguestfs which
> will keep running forever and if it will bring more trouble.
User-Mode Linux is also a possibility.  Slow but consistent
performance.  Unfortunately it lacks several important features
(notably qcow2 support).  The other unfortunate thing is that we
didn't support UML in 1.20 -- it was added in 1.24.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-builder quickly builds VMs from scratch
http://libguestfs.org/virt-builder.1.html

On Mon, Sep 29, 2014 at 1:27 AM, Richard W.M. Jones <rjones@redhat.com>
wrote:
> On Mon, Sep 29, 2014 at 01:22:19AM +0800, Zhi Yong Wu wrote:
>> Yes, I am trying to run it in Xen Domain0. I thought that we can use
>> Domain0 as a public libguestfs VM, This will avoid starting a new
>> guest for virt-xxx every time, But Domain0 has no corresponding qemu
>> task. So this way isn't available.
>> Now, i am considering if we can run private VM for libguestfs which
>> will keep running forever and if it will bring more trouble.
>
> User-Mode Linux is also a possibility.  Slow but consistent
Slow is a big concern...
> performance.  Unfortunately it lacks several important features
> (notably qcow2 support).  The other unfortunate thing is that we
No matter, our image all use vhd or raw, not qcow2.:)
> didn't support UML in 1.20 -- it was added in 1.24.
>
> Rich.
>
> --
> Richard Jones, Virtualization Group, Red Hat
http://people.redhat.com/~rjones
> Read my programming and virtualization blog: http://rwmj.wordpress.com
> virt-builder quickly builds VMs from scratch
> http://libguestfs.org/virt-builder.1.html


-- 
Regards,

Zhi Yong Wu