Re: [CentOS] Install CentOS as KVM guest

Re: [CentOS] Install CentOS as KVM guest

[Emmanuel Noobadmin]

Unfortunately, things still don't work.

<rant>
It's just ridiculous that the installer under KVM does not detect the
cdrom drive it was booted from. Trying to do a net-install doesn't
work, maybe I messed up the networking even though br0 and eth0 is
working on the host.

Nevermind, let's install apache and use the mounted ISO. Verified
apache is working and the CentOS folder is accessible via web browser.
But, still the guest installer cannot seem to access the installation
files.

OK, so maybe I messed up the networking, after all I am the noob...
maybe specifying --network=bridge:br0 isn't enough. There was
something about a tap or tunnel when initially reading up on bridged
networking. Looking up more on this, there are several resources
(sorry KVM FAQ leads to a page that no longer exist) which like many
other instructions, give the commands without really explaining
what/why.

So I have to run some tunctl command and scripts to add a bridge and
tunnel/tap... but wait, I already made my bridge, will running the
script kill my networking by creating a second bridge? Especially the
warning about temporarily loosing connectivity due to ifcfg1 being
reset.

And if I need to run this script everytime in order to activate the
bridge and tunnel, doesn't that mean all my guest OS are screwed if
the host reboots while I'm not around? Shouldn't these things go into
permanent files like if-tun0 or something?

Every year, I get a little closer to not using VMWare but it seems
like this year is going to be victory for VMWare again.

CC to kvm mailing list but I expect, like my previous request for help
to the list, it will be rejected by mailman or a moderator.
</rant>

Just damn frustrated, even if it's probably just me being too stupid
to know how to use KVM.

Re: [CentOS] Install CentOS as KVM guest

[Simon Grinberg]

----- Original Message -----
> From: "Emmanuel Noobadmin" <centos.admin@gmail.com>
> To: "CentOS mailing list" <centos@centos.org>, "kvm" <kvm@vger.kernel.org>
> Sent: Tuesday, April 26, 2011 11:57:18 PM
> Subject: Re: [CentOS] Install CentOS as KVM guest
> Unfortunately, things still don't work.
> 
> <rant>
> It's just ridiculous that the installer under KVM does not detect the
> cdrom drive it was booted from. Trying to do a net-install doesn't
> work, maybe I messed up the networking even though br0 and eth0 is
> working on the host.
> 
> Nevermind, let's install apache and use the mounted ISO. Verified
> apache is working and the CentOS folder is accessible via web browser.
> But, still the guest installer cannot seem to access the installation
> files.
> 
> OK, so maybe I messed up the networking, after all I am the noob...
> maybe specifying --network=bridge:br0 isn't enough. There was
> something about a tap or tunnel when initially reading up on bridged
> networking. Looking up more on this, there are several resources
> (sorry KVM FAQ leads to a page that no longer exist) which like many
> other instructions, give the commands without really explaining
> what/why.
> 
> So I have to run some tunctl command and scripts to add a bridge and
> tunnel/tap... but wait, I already made my bridge, will running the
> script kill my networking by creating a second bridge? Especially the
> warning about temporarily loosing connectivity due to ifcfg1 being
> reset.
> 
> And if I need to run this script everytime in order to activate the
> bridge and tunnel, doesn't that mean all my guest OS are screwed if
> the host reboots while I'm not around? Shouldn't these things go into
> permanent files like if-tun0 or something?
> 
> Every year, I get a little closer to not using VMWare but it seems
> like this year is going to be victory for VMWare again.

What version of VMWare are you using?

> 
> CC to kvm mailing list but I expect, like my previous request for help
> to the list, it will be rejected by mailman or a moderator.
> </rant>
> 
> Just damn frustrated, even if it's probably just me being too stupid
> to know how to use KVM.
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos

Re: Install CentOS as KVM guest

[Emmanuel Noobadmin]

On 4/28/11, Simon Grinberg <simon-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> What version of VMWare are you using?

Currently, I'm not using VMWare yet on this new server as I really do
hope to be able to use an "unified" solution. But so far, it's just
one brickwall after another. I've given myself until this weekend to
get things working or just go the easy way.

Previously, I've used VMServer 2 as well as VMPlayer 3. All running
off CentOS 5.x host.

Re: [CentOS] Install CentOS as KVM guest

[Gleb Natapov]

On Wed, Apr 27, 2011 at 04:57:18AM +0800, Emmanuel Noobadmin wrote:
> Unfortunately, things still don't work.
> 
> <rant>
> It's just ridiculous that the installer under KVM does not detect the
> cdrom drive it was booted from. Trying to do a net-install doesn't
> work, maybe I messed up the networking even though br0 and eth0 is
> working on the host.
> 
> Nevermind, let's install apache and use the mounted ISO. Verified
> apache is working and the CentOS folder is accessible via web browser.
> But, still the guest installer cannot seem to access the installation
> files.
> 
> OK, so maybe I messed up the networking, after all I am the noob...
> maybe specifying --network=bridge:br0 isn't enough. There was
So why don't you use virt-manager?

> something about a tap or tunnel when initially reading up on bridged
> networking. Looking up more on this, there are several resources
> (sorry KVM FAQ leads to a page that no longer exist) which like many
> other instructions, give the commands without really explaining
> what/why.
> 
> So I have to run some tunctl command and scripts to add a bridge and
> tunnel/tap... but wait, I already made my bridge, will running the
> script kill my networking by creating a second bridge? Especially the
> warning about temporarily loosing connectivity due to ifcfg1 being
> reset.
> 
> And if I need to run this script everytime in order to activate the
> bridge and tunnel, doesn't that mean all my guest OS are screwed if
> the host reboots while I'm not around? Shouldn't these things go into
> permanent files like if-tun0 or something?
> 
> Every year, I get a little closer to not using VMWare but it seems
> like this year is going to be victory for VMWare again.
> 
> CC to kvm mailing list but I expect, like my previous request for help
> to the list, it will be rejected by mailman or a moderator.
> </rant>
> 
> Just damn frustrated, even if it's probably just me being too stupid
> to know how to use KVM.
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

--
			Gleb.

Re: Install CentOS as KVM guest

[Emmanuel Noobadmin]

On 4/28/11, Gleb Natapov <gleb-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> So why don't you use virt-manager?

The original intention was to run the host without any graphical
desktop or anything not necessary to host the guests. That was based
on reading and such which recommends not having anything beyond the
necessary to minimize potential security problems and maximize
resources available.

Then there were those pages which warn that virt-manager didn't work
too well if bridged networking was required.

Last but not least, when I finally gave up and installed the desktop,
virt-manager couldn't find the hypervisor. Checking up, it appears
that the user needed additional permissions to certain files, which
after given and tested via CLI, I still get errors.

Starting up X as root gave me this ominous warning that I really
shouldn't be doing this and since I didn't think it was wise in the
first place to have the desktop with root access running on what's
supposed to be a production machine, I stopped trying that route and
went back to figuring how to get virt-install to work.

Re: [CentOS] Install CentOS as KVM guest

[Gleb Natapov]

On Thu, Apr 28, 2011 at 07:46:28PM +0800, Emmanuel Noobadmin wrote:
> On 4/28/11, Gleb Natapov <gleb@redhat.com> wrote:
> > So why don't you use virt-manager?
> 
> The original intention was to run the host without any graphical
> desktop or anything not necessary to host the guests. That was based
> on reading and such which recommends not having anything beyond the
> necessary to minimize potential security problems and maximize
> resources available.
> 
Qemu is not intended to be used directly by end user. It is too complex as
you already found out. VMware don't even give you access to such low parts
of virt stack. You should use libvirt or virt-manager instead. Especially
if you are concerned about security. I think libvirt can start guest on
headless server.

If this still fails for you you need to complain to libvirt developers
(not in a rant mode, but providing details of what exact version of
software you have problem with and what are you trying to do). And
libvirt developers will not be shy to complain to qemu developers if the
problem turned to be on their side.

> Then there were those pages which warn that virt-manager didn't work
> too well if bridged networking was required.
As far as I know libvirt has no problem using bridged networking and
virt-manager use libvirt so it should work if you use new enough virt
stack, but you should ask on libvirt mailing list instead.

> 
> Last but not least, when I finally gave up and installed the desktop,
> virt-manager couldn't find the hypervisor. Checking up, it appears
> that the user needed additional permissions to certain files, which
> after given and tested via CLI, I still get errors.
What distribution are you using? I didn't saw recent Fedoras having such
problems (admittedly I do not use libvirt/virt-manager much).

> 
> Starting up X as root gave me this ominous warning that I really
> shouldn't be doing this and since I didn't think it was wise in the
> first place to have the desktop with root access running on what's
> supposed to be a production machine, I stopped trying that route and
> went back to figuring how to get virt-install to work.

--
			Gleb.

Re: [CentOS] Install CentOS as KVM guest

[Emmanuel Noobadmin]

On 4/28/11, Gleb Natapov <gleb@redhat.com> wrote:
> Qemu is not intended to be used directly by end user. It is too complex as
> you already found out. VMware don't even give you access to such low parts
> of virt stack. You should use libvirt or virt-manager instead. Especially
> if you are concerned about security. I think libvirt can start guest on
> headless server.

Sorry for the confusion, I was using libvirtd in CLI, i.e.
virt-install and virsh, not qemu directly.

> If this still fails for you you need to complain to libvirt developers
> (not in a rant mode, but providing details of what exact version of
> software you have problem with and what are you trying to do). And
> libvirt developers will not be shy to complain to qemu developers if the
> problem turned to be on their side.

Apologies about the rant mode as well. Before that, I tried sending
two emails (25th and 26th Apr) to the KVM list with some details,
hoping to get some advice. But each of these failed to materialize on
the kvm list for unknown reasons.

So I resorted to posting to the CentOS list, where I did get some
response for which I'm very thankful. The rant post came when despite
the additional advice which helped me get a little further, I keep
running into unexpected brickwalls like anaconda not seeing the "dvd"
(mounted ISO specified using --location) that it just booted from.

Out of frustration, I CC'd that particular email to the kvm list,
figuring that since it's likely to get me flamed, the imp of
perversity would probably let it through... and it did.

> As far as I know libvirt has no problem using bridged networking and
> virt-manager use libvirt so it should work if you use new enough virt
> stack, but you should ask on libvirt mailing list instead.

I guess those were outdated warnings on older versions. I'll give it
another spin given some of the new suggestions like using virt-install
to create the disk file. If it still doesn't work, I'll go check the
libvirt ML (I'm belatedly getting the idea that libvirt is not part of
kvm).

Re: [CentOS] Install CentOS as KVM guest

[Emmanuel Noobadmin]

On 4/28/11, Gleb Natapov <gleb@redhat.com> wrote:
> of virt stack. You should use libvirt or virt-manager instead. Especially
> if you are concerned about security. I think libvirt can start guest on
> headless server.
>
> If this still fails for you you need to complain to libvirt developers
> (not in a rant mode, but providing details of what exact version of
> software you have problem with and what are you trying to do). And
> libvirt developers will not be shy to complain to qemu developers if the
> problem turned to be on their side.

I've finally got an installation working, not using virt-install or
virt-manager. After reading through the libvirt site, I started
writing the domain definition manually.

Through trial and error, comparison with what virt-install generated
and the online examples, I got a working xml. Just for the record,
virsh --version reports 0.8.1

For the benefits of other newbies, my discovery so far is that

1. No-activity after the guest VM started
Originally, when I specified the CentOS DVD ISO, the guest will load
and then do nothing but chew up 100% CPU cycle on the allocated 1 vcpu
for quite some time. Subsequently, it appeared that mounting the ISO
as loop back is the solution. This seemed to imply that libvirt or KVM
couldn't boot a guest from ISO... which didn't quite make sense.

I ran into the issue when using my manually generated XML, it turned
out that the reason was the permissions (644) on vmlinuz and
initrd.img on the DVD. By copying the two files to local disk,
changing the permissions and using the <initrd> and <kernel> options,
I was able to boot the guest.

I was curious how virt-install got around this and learnt that I could
dump the config from a running machine. It turns out that virt-install
didn't exactly use the .xml it created, it added stuff to the running
version. Importantly making a temporary copy of initrd.img and
vmlinuz. I think the ISO problem with virt-install may be that it was
unable to mount the ISO to copy these files despite me running it as
root.


2. Anaconda couldn't see the DVD
Which was my rant earlier, since it sounded really stupid that the
installer couldn't see the disc it just booted off. Now, with #1
solved, it seems that anaconda wasn't booting off the disc after all.

However, the interesting thing here is that once I got past #1, My
guest could install from the DVD.

After comparing the xml files, it seems the problem is virt-install
did not save the path to the ISO/mounted DVD. Under the <disk>
element, there wasn't a source. With my manually generated xml,
specifying the ISO as the source worked.

But the virt-installed anaconda was complaining I don't have any hard
disks or cdroms. Not that there was no disk in the drive. Everytime I
picked an option like install media in HDD or CDROM, it prompted me no
device, do I want to install a driver. Since the hard disk definition
appears to be the same, I'm not sure why that happened with
virt-install's xml but not mine.


So right now, I managed to get the OS installed, rebooting it required
removing the initrd and kernel entry as well as the source so that it
would boot from the image disk.

Only problem is... networking still isn't working although brctl show
on the host shows that a vnet0 had been created and attached to the
bridge. Any pointers would be appreciated!

Re: [CentOS] Install CentOS as KVM guest

[Emmanuel Noobadmin]

On 4/29/11, Emmanuel Noobadmin <centos.admin@gmail.com> wrote:
> Only problem is... networking still isn't working although brctl show
> on the host shows that a vnet0 had been created and attached to the
> bridge. Any pointers would be appreciated!


Just to close off on this issue for the benefit of any future clueless
newbies like me, networking wasn't working due to one missing element
in the .xml

<model type='virtio' /> was the missing ingredient.

Re: [CentOS] Install CentOS as KVM guest

[Gleb Natapov]

On Sat, Apr 30, 2011 at 03:47:50AM +0800, Emmanuel Noobadmin wrote:
> On 4/29/11, Emmanuel Noobadmin <centos.admin@gmail.com> wrote:
> > Only problem is... networking still isn't working although brctl show
> > on the host shows that a vnet0 had been created and attached to the
> > bridge. Any pointers would be appreciated!
> 
> 
> Just to close off on this issue for the benefit of any future clueless
> newbies like me, networking wasn't working due to one missing element
> in the .xml
> 
> <model type='virtio' /> was the missing ingredient.
Thanks you for digging dipper. I am sure this shouldn't be so
complicated though. Can you share you experience with libvirt team?

http://libvirt.org/contact.html

--
			Gleb.

Re: [CentOS] Install CentOS as KVM guest

[Emmanuel Noobadmin]

On 5/3/11, Gleb Natapov <gleb@redhat.com> wrote:

> Thanks you for digging dipper. I am sure this shouldn't be so
> complicated though. Can you share you experience with libvirt team?
>
> http://libvirt.org/contact.html

Sorry for the late response, I posted to the libvirtd mailing list as
you suggested. But I suspect it's not going to appear, like many of my
attempted posts to the KVM mailing lists. Maybe somebody blacklisted
my email or maybe it's just gmail :D