Xen Performance

Kai Schaetzl maillists at conactive.com
Thu Oct 23 18:31:21 IST 2008

Greg Matthews wrote on Thu, 23 Oct 2008 14:21:11 +0100:

> dont use xvd block devices? why not? what is the alternative?

You can use ext3 on LVs directly. Advantage is that you have all the 
repair tools at hand and that you can access the filesystem from dom0 by 
simply mounting it. You can do that even at runtime (I have to admit I did 
this only once or twice accidentally and wouldn't recommend making it a 
habit). Also makes backups easier in my eyes, I find it extremely handy 
this way.
Some installers (like RHEL/CentOS 5) will not allow installation directly 
on such an LV and force the use of xvd, anyway. So, if you want to convert 
to such a setup you have to move the content of the xvda disk first to a 
new formatted LV. That is surely not worth it for short-lived VMs, but if 
you have VMs that are bound to run for years and get some good load I 
think it's worth it. I've got template disks for this case which I just 
duplicate and then start with a new config file.

There might also be performance advantages in some situations, I don't 


Kai Schätzl, Berlin, Germany
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