Re: Xen Dom0 5.0_STABLE and shared disks

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Sun, Sep 13, 2009 at 01:03:52PM +0200, Juraj Hercek wrote:
> Hello,
> 
> I've been using domU domains with shared disks in read only mode with 
> the 5.99.X dom0 kernels. Now, I've switched to stable branch and I 
> figured out I cannot do this anymore with 5.0_STABLE dom0 kernel.
> 
> This is what I used to use in domU config files:
> 
> domU_1:
> ...
> disk = [ 'phy:/dev/wd0g,0x01,w',
>          'phy:/dev/wd0f,0x02,r' ]
> ...
> 
> domU_2:
> ...
> disk = [ 'phy:/dev/wd0h,0x01,w',
>          'phy:/dev/wd0f,0x02,r' ]
> ...
> 
> This doesn't work anymore. When starting domU_2, xenback complains about 
> failing VOP_OPEN with errno 16 (EBUSY). When wd0f was mounted in dom0, 
> even domU_1 failed with the same/similar error.
> 
> Is there any workaround besides exporting disks via NFS (resp. iSCSI)? 
> I'd like to avoid networked solution (NFS, iSCSI) in order to save some 
> CPU ticks spent on ip stack code.

I don't know of a sane solution to this. A workaround is to define
2 partitions with the same start/size in wd0's disklabel.
Another workaround is to switch to file-backed virtual disks.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--