[ovirt-users] oVirt/gluster storage questions for 2-3 node datacenter

[David King]

Hi Paul,

I would prefer to do a direct mount for local disk.  However I am not certain how to configure a single system with both local storage and bluster replicated storage.

- The “Configure Local Storage”  option for Hosts wants to make a datacenter and cluster for the system.  I presume that’s because oVirt wants to be able to mount the storage on all hosts in a datacenter.  

- Configuring a POSIX storage domain with local disk does not work as oVirt wants to mount the disk on all systems in the datacenter.  

I suppose my third option would be to put these systems as libvirt VMs and not manage them with oVirt.  This is fairly reasonable as I use Foreman for provisioning except that I will need to figure out how to make them co-exist.  Has anyone tried this?

Am I missing other options for local non-replicated disk?  

Thanks,
David

-- 
David King
On August 29, 2014 at 3:01:49 PM, Paul Robert Marino (prmarino1 at gmail.com) wrote:

On Fri, Aug 29, 2014 at 12:25 PM, Vijay Bellur <vbellur at redhat.com> wrote:  
> On 08/29/2014 07:34 PM, David King wrote:  
>>  
>> Paul,  
>>  
>> Thanks for the response.  
>>  
>> You mention that the issue is orphaned files during updates when one  
>> node is down. However I am less concerned about adding and removing  
>> files because the file server will be predominately VM disks so the file  
>> structure is fairly static. Those VM files will be quite active however  
>> - will gluster be able to keep track of partial updates to a large file  
>> when one out of two bricks are down?  
>>  
>  
> Yes, gluster only updates regions of the file that need to be synchronized  
> during self-healing. More details on this synchronization can be found in  
> the self-healing section of afr's design document [1].  
>  
>  
>> Right now I am leaning towards using SSD for "host local" disk - single  
>> brick gluster volumes intended for VMs which are node specific and then  

I wouldn't use single brick gluster volumes for local disk you don't  
need it and it will actually make it more complicated with no real  
benefits.  

>> 3 way replicas for the higher availability zones which tend to be more  
>> read oriented. I presume that read-only access only needs to get data  
>> from one of the 3 replicas so that should be reasonably performant.  
>  
>  
> Yes, read operations are directed to only one of the replicas.  
>  
> Regards,  
> Vijay  
>  
> [1] https://github.com/gluster/glusterfs/blob/master/doc/features/afr-v1.md  
>  
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