[linux-lvm] lvm on a share environnement (SAN inside)

[hubert chomette]

but the vg can be accessed by the two host.
For example:
on xen1, there is vm1, vm2, vm3 and vm4  access from SAN by /dev/ 
domU_VG/vm{1,2,3,4}-disk
on xen2, there is vm5, vm6, vm7 and vm8  access from SAN by /dev/ 
domU_VG/vm{5,6,7,8}-disk

If xen1 comes down, vm1,vm2,vm3 and vm4 are reload (manually or by  
script) on xen2
If there is intendance task on xen2, simply migrate vm{5,6,7,8} on xen1

There is no filesystem access simulty but the same vg is seen by the  
two host.

thank's for your help ;)





Le 27 sept. 07 à 23:12, Chris Cox a écrit :

> hubert chomette wrote:
>> the two machine use the same lun, on this lun, there is one vg with a
>> logical volume by virtual machine (10 virtual machine).
>> The idea is if one xen is down, the other can launch the virtual  
>> machine
>> ad continu service.
>
> Ok..  so the psedo HA model I mentioned.  Access to the LUN isn't live
> (in concept) but only becomes available to the failover system when
> the primary system fails.
>
> Nothing wrong with this.  Remember, that when you disconnect
> a LUN and reconnect it to a new host that it will scan what is
> out there.  The difficulty would be for hardcoded names of
> volumes, etc, if you changed those things while the secondary
> system is in charge (same issue with the config on the secondary
> when the primary is in charge).
>
>  You might be able to do something
> with auto discovery and a script rather than with fstab with
> regards to bring LUN LVM filesystem back online.  That's probably
> how I'd do it... That way, you can at least take a good stab
> of making sense of the LVM when it comes online.
>
>
>>
>> Le 27 sept. 07 à 19:36, Chris Cox a écrit :
>>
>>> hubert chomette wrote:
>>>> Hi,
>>>> I recently install a SAN at my work. One lun is used for XEN and  
>>>> can be
>>>> used by two xen server.
>>>> For more flexibility I use lvm on this lun. I was very happy of the
>>>> result, unless I discover (during a conversation with a friend)  
>>>> that lvm
>>>> metadata can be compromised if the two server simulty modify  
>>>> metadata.
>>>> - So what can I do?
>>>
>>> Use seperate LUNs.  I'm not sure what your friend is talking about.
>>> Unless you have two machines using the same LUN, in which case
>>> there are issues... this would be a cluster filesystem issue, or
>>> near-high availability issue...
>>>
>>>> - Is it possible to allow LVM metadata modification by only one  
>>>> server?
>>>> - should I use clvm instead?
>>>
>>> Metadata won't creep outside of what is visible.
>>>
>>>> - Is it possible to migrate lvm to clvm without any data lost?
>>>
>>> Not sure.
>>>
>>>>
>>>> thank's for your help
>>>>
>>>> regards,
>>>>
>>>> ps: sorry for my poor english
>>>>
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> linux-lvm mailing list
>>>> linux-lvm at redhat.com
>>>> https://www.redhat.com/mailman/listinfo/linux-lvm
>>>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>>>>
>>>
>>>
>>> -- 
>>> Chris Cox
>>> Sr. Unix Sys Admin
>>>
>>> _______________________________________________
>>> linux-lvm mailing list
>>> linux-lvm at redhat.com
>>> https://www.redhat.com/mailman/listinfo/linux-lvm
>>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>>>
>>
>>
>> _______________________________________________
>> linux-lvm mailing list
>> linux-lvm at redhat.com
>> https://www.redhat.com/mailman/listinfo/linux-lvm
>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>>
>
>
> -- 
> Chris Cox
> Sr. Unix Sys Admin
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm at redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>