[ovirt-users] is ovirt-node.iso supposed to create a readonly filesystem?

[Jeremiah Jahn]

On Thu, Apr 10, 2014 at 5:46 AM, Fabian Deutsch <fabiand at redhat.com> wrote:
> Am Donnerstag, den 10.04.2014, 09:19 +0300 schrieb Itamar Heim:
>> On 04/09/2014 11:01 PM, Jeremiah Jahn wrote:
>> > I'm assuming the answer is no. But for some reason I seem to be
>>
>> the answer is yes actually. if you want a host you can change, use plain
>> fedora/rhel/centos as the host.
>> Fabian can reply to the rest.
>
> Yep. Node has a read-only root filesystem, which has some overlays to
> allow limited changes.

And yet I've been able to edit the /etc/hosts file before this
problem? Does it go readonly after a while?

>
>> > getting LVM volume group UUID overruns.
>
> Do you mean collisions here, or can you explain it a bit more.
>
>> > I'm using direct attach fiber
>> > channel, and everything looks good, but there appears to be some UUID
>> > or Volume group name in my list of LUNs that matches  some sort of lvm
>> > key from the node root file system.  This only happens on the node
>> > that I installed from the iso. I built all of these nodes in a vm,
>> > then set that image to boot. I did NOT copy that lun from one top the
>> > others, nor are any of the hosts luns visible from any of the other
>> > hosts.  Not sure where to start. I'm going to reinstall from a
>> > bootable cd directly connected to my blade and see if that clears up
>> > the problem.
>
> Could you please explain abit more about your setup.
> If you have a SAN, an all LUNs of it are visible by all hosts, and you
> install Node on more than one host, then it could come to collisions.

Yes, I have a SAN, The only LUNs visible to all hosts are guest luns.
But apparently one of those guest luns has an LV named Root.   When
the VG Scan runs it picks up all of the volume groups on every lun,
and seems to be using the LAST one it finds as the prefered drive. So
in place of /dev/sda1 becoming the root, it seems some other partition
from some other lan was chosen. I can't seem to track down which other
lun yet.  I can't seem to find a path between /dev/dm-31 and the
actual partition it's using, only /dev/lvm-Root (or something..).
Would have helped just a little if there had been a tool to edit/view
GTP partitions btw. Given that it's a read only file system, I
couldn't install them.

>
> Node is using some predefined LV names, e.g. Root, which will cause
> collisions if there are more LUNs with LVs which have the same name.

yes... That's going to be a problem you know. There should be a way to
choose the LV Name, or randomize it, add a namespace to it, or let the
user do a different layout of their partitions.  I think the namespace
would solve a lot of problems. Using 'Root' as the VG name will always
have a chance of colliding, in a direct attach setup.
'ovirt-node-root' on the other hand is probably pretty safe.  Because
lord only knows what one of the other people is going to drop out and
try on some lun.


thanks so much for the help.

>
> Greetings
> fabian
>