[Xen-users] modifying file-systems in Dom0 while mounted read-only in DomU

[Reinhard Brandstädter <reinhard.brandstaedter@xxxxxx>]

Hello,

I was quite surprised this worked:
I started two virtual machines that both use the same physical partition 
residing on a SAN (exported read-only by the Xen configuration).
While both machines were running I mounted the partition in the Dom0 and 
changed some files there. These changes were NOT visible in the DomUs, but 
when I shut down one of the DomUs and started it again with 'xm create' it 
had the changes, while the other DomU didn't.

So while it's not possible to create DomUs with disks that are currently 
mounted in the Dom0, it is possible to mount disks in the Dom0 that are 
currently in use by a DomU?

Although this is a nice feature  - in my case these two DomUs are forming a 
cluster and the common configuration resides on the read-only disk - it seems 
dangerous to me.

Although with this feature I could seamless change the configuration of the 
cluster :-) :
- mount the partitition in Dom0
- restart one DomU and let it gain the service with changed configuration
- restart the second DomU with the new configuration

Is there a reason why this is possible? Maybe it isn't dangerous at all?

Reinhard

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