[Users] problems with thin provisioned LUN's for oVirt node

[Johan Kragsterman]

Hi!

I'd like to share a few things regarding installation(and use) of oVirt node on thin provisioned LUN's. I had problems here, perhaps someone else have noticed similarities?

I use ZFS and comstar on solaris to provide volume's and LUN`S to the fibre channel SAN. When I create a thin provisioned LUN in comstar it uses the format qcow2, to be able to "fool" the OS that installs on it about the real size of the LUN.

This seem to work fine with normal OS installation, but I'm doubtful about oVist node. I had issues, especially when I try to reinstall on the same LUN. During reinstallation it seems that the installation process tries to "clean" the LUN with dd if=/dev/zero , and that seem to be difficult.

I've run the same cleaning process on different LUN's provided with the same qcow2 format with live media, to see what happens. 

First time it seems to go fine, but after one cleaning and another partitioning with LVM the dd seems to get stuck. My feeling is that the LVM partitioning seems to get stuck on the LUN and difficult to get rid of...? Perhaps due to the qcow2 format...?

Could this have something to do with "nested qcow"? qcow on qcow...?"

So, when I get to this stage, the LUN becomes unusable for oVirt node installation. I don't know yet about installing other software, like a normal linux os...

The only oVist node's I've been able to try this on is Fc16-based, since the Fc17 have problems with the qlogic HBA's that I use in my SAN. Fc 17 doesn't load the qlogic firmware image, which makes it impossible to install on the LUN's visible through the qlogic HBA's.

So, anyone that can comments, views, other perspectives, etc, on these subjects are wellcome to do so...

Rgrds Johan