RE: [Xen-users] Shared storage between Domu's

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Niv Elad
> Sent: 08 March 2007 13:28
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-users] Shared storage between Domu's
> 
> Hello
>  
> I have two domains running on the same Dom0.
> I want to allocate shared disk  to both of them (i want to 
> simulate cluster envinroment).
>  
> Does anyone know whether this is possible and if so how can 
> it be done?

Yes, but if you actually want to write to the file-system, you will need
a cluster-file-system that "tolerates" multiple writers to the same
file-system. Most filesystems assume that there can only be writes from
one origin, and thus that the writes are "synchronized" by the writer.
In a cluser-file-system, this is not assumed, and thus there are
mechanisms in the filesystem to cope with multiple writes from different
machines (or such). 

I'm not an expert on cluster file systems, but google turns up: 
OCFS, GFS and Lustre amongst some other things. 

For a very "easy" but not optimal solution, you may want to set up an
NFS mount and let the guests use that - NFS isn't a cluster file system,
but it allows multiple machines to write to the same "disk". (because
it's sequentialized through the NFS daemno). 

--
Mats
>  
> This is my disk defenition for the domains - 
>  
> DomU1:
> disk=['phy:vgxen01/lv_linva04_hda,hda,w','phy:vgxen01/lv_linva
> 04_06_hdb,hdb,w']
>  
> DomU2:
> disk=['phy:vgxen01/lv_linva06_hda,hda,w','phy:vgxen01/lv_linva
> 04_06_hdb,hdb,w']
>  
> When trying to start second DomU i am getting the following - 
>  
> Error: Device 5632 (vbd) could not be connected.
> Device /dev/vgxen01/lv_linva04_06_hdb is mounted in a guest domain,
> and so cannot be mounted now.
>  
>  
> Cheers
>  
> Niv 
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>       
> 



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