[CentOS] drbd xen question

Thu Aug 20 15:38:54 UTC 2009
Alan Sparks <asparks at doublesparks.net>

Ross Walker wrote:
> On Aug 20, 2009, at 10:22 AM, Coert Waagmeester <lgroups at waagmeester.co.za 
>  > wrote:
>   
>> Hello all,
>>
>>
>> I am running drbd protocol A to a secondary machine to have  
>> 'backups' of
>> my xen domUs.
>>
>> Is it necessary to change the xen domains configs to use /dev/drbd*
>> instead of the LVM volume that drbd mirrors, and which the xen domU  
>> runs
>> of?
>>     
>
> Yes otherwise the data won't be replicated and your drbd volume will  
> be inconsistent and need resync'd.
>
> -Ross
>
> _______________________________________________
>   

To be clear, are you saying you have a DRBD partition on both host
machines, and LVM on top of that to allocate LVs for host storage?

You would not want to bypass the LVM layer in that case.  The hosts
would be still configured to map the LV devices into the domUs.  You
need to go through the LVM layer, which uses the DRBD partition as a
block physical device.  The writes down through the DRDB layer will
still be replicated.
-Alan