[CentOS-virt] xen setup documentation for centos?

Wed Jun 4 02:12:55 UTC 2014
lee <lee at yun.yagibdah.de>

George Dunlap <dunlapg at umich.edu> writes:

> On Mon, Jun 2, 2014 at 1:45 AM, lee <lee at yun.yagibdah.de> wrote:
>> Hi,
>> what is the proposed way to create domU guests on centos 6.5?  At first
>> I tried to follow the documentation on the xen project website which
>> recommends using xl.  I created a config file and ended up with getting
>> a message that the kernel is not bootable when trying to create a guest.
>> I also had to stop some daemon (xend?) because it said that xl isn`t
>> compatible with it and the daemon must be stopped first.
> I understand how frustrating it can be to be dealing with old /
> inaccurate documentation.  But I'm not sure how we're supposed to help
> you if you don't give any details about what you did and exactly how
> it failed.

I was merely trying to create a VM on a centos host, using xen.  Hence
my question what "the centos way" of doing this (without a GUI) is.

By trial and error, I found that creating them with virsh-install works.
Yet it seems to me as if virsh is an additional layer which makes
dealing with VMs a lot easier at the cost of increased resource usage.
My intention was to avoid this and to create VMs "the xen way" --- which
apparently doesn`t work with centos.

> If the instructions you followed don't work, then either:
> * You misunderstood something / accidentally left out a step /
> mistyped something from the documentation.
> * There's a bug in the CentOS implementation of Xen that needs to be fixed
> * There's a bug in the documentation that needs to be fixed

There seem to be at least three different ways to create VMs, two of
which have been used at different times with xen, while virsh tries to
give users a common interface which isn`t exactly needed when you want
to stick to xen and therefore do things "the xen way".

But then, I guess every distribution has their own way to make things
more complicated, so a common interface like virsh seems to be the most
efficient way.

> If you describe which bit of documentation on the Xen website you
> tried to follow, what you were trying to do, and what happened, then
> we can figure out which of those it is and address the issue.

Well, I didn`t really care about the documentation that didn`t work.
Like I said, using xl didn`t work because it only says the kernel can`t
be booted; xm seems to be deprecated (yet still used with centos), and
virsh-install works.

> The xend thing is an unfortunate -- as a project we're trying to move
> away from it, but there are still a large number of CentOS users who
> use it.  Trying to make both new users and old users happy is a bit of
> a hard balancing act.

There could be different packages in centos, one set featuring xend, the
other featuring whatever replaces it.

I`ve come to like virsh because it`s pretty straightforward and actually
works.  From that point of view, it doesn`t matter to me whether xend is
used or xl or xm or something else.  It only matters when I`m concerned
about what might be more efficient or have other advantages relevant to

Since xend and xm are appartenly deprecated and will or have been
replaced, I don`t see much point in learning them and figuring out how
they might be advantageous.  I rather learn to use what is current and
may be used in the future.

Knowledge is volatile and fluid.  Software is power.