On Thursday 04 May 2006 16:14, Nic wrote:
> Is it possible to mount a cow file and it's backing fs as a loop back
> filesystem on the host?
> ie: shut down your VM and mount the VMs filesystem on the host in
> order to write something into it?
No, there's no way to mount COW files on host. Use plain UBD files if you need
that,or access them from UML itself (this doesn't work in a recovery
However, there's a (hard) way: you can use device-mapper (dmsetup command) to
do the same job - you can create a COW volume on the host with two block
devices* (via the snapshot target, see
Documentation/device-mapper/snapshot.txt in a 2.6.15+ linux kernel tree) and
pass it to UML as ubd0=/dev/mapper/volume after giving write access on the
It's not easy to do however, I wanted to write an interface for this but
didn't finish it. In particular, you can create the volume with two LVM
devices, but the creation of a COW volume cannot be done with LVM,it does not
provide this ability.
* two partitions or more likely two LVM volumes.
Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894)
Chiacchiera con i tuoi amici in tempo reale!
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