[ovirt-users] Storage questions

[Oscar Segarra]

possible unrecoverable gluster bugs" is a sweeping statement. Do you have
any particular issue that you can refer us to?

No, I don't have experienced any issue, but if under heavy loads a new one
appears, In this environment I could leave 1000 vdi out of service (or 1000
people without their workplace.

Once clarified all questions, with oVirt, is it possible to achieve this
architecture (or similar) ?

Do you have any customer who has run out a gluster environment for heavy
load vdi ?

Thanks a lot.


2016-11-23 9:01 GMT+01:00 Sahina Bose <sabose at redhat.com>:

>
>
> On Wed, Nov 23, 2016 at 1:18 PM, Oscar Segarra <oscar.segarra at gmail.com>
> wrote:
>
>> Hi,
>>>
>>> As on oVirt is it possible to attach local storage I supose it can be
>>> used to run virtual machines:
>>>
>>> I have drawn a couple of diagrams in order to know if is it possible to
>>> set up this configuration:
>>>
>>> 1.- In on-going scenario:
>>> Every host runs 100 vdi virtual machines whose disks are placed on local
>>> storage. There is a common gluster volume shared between all nodes.
>>>
>>> [image: Imágenes integradas 1]
>>>
>>
>> With local storage you end up losing many of the benefits of shared
>> storage - including migration and HA.
>> If you do have SSD on your physical hosts, have you considered building
>> gluster volume using these? This could give you improved performance.
>> Regarding performance, I think it is best that you run a test comparing
>> gluster storage performance with local storage and see if this is
>> acceptable to you. Please share the results in case you do.
>>
>> Yes, but I want to avoid possible corruption problems due to possible
>> unrecoverable gluster bugs.
>> We have to make some developement and I don't want to spend money in this
>> process and then discover that the performance is not good enought and have
>> to do a
>>
>
> "possible unrecoverable gluster bugs" is a sweeping statement. Do you have
> any particular issue that you can refer us to?
>
>
>>
>>
>> In the above diagram each host is in its own cluster - as all hosts in a
>> cluster should have access to the storage domain?
>>
>> Yes, every host has ho have access to two storage domains: The local one
>> and the shared gluster one.
>>
>> Is the gluster volume for backup served from a separate set of server?
>>
>> No, each host will have 2 disks /dev/sdb1 (for runing vm on local
>> storage) and /dev/sdc1 (for shared gluster where store backups)
>>
>>
>>>
>>> 2.- If one node fails:
>>>
>>> [image: Imágenes integradas 2]
>>>
>>> oVirt has to be able to inventory the copy of machines (in our example
>>> vdi201 ... vdi300) and start them on remaining nodes.
>>>
>>> ¿Is it possible to reach this configuration with oVirt? ¿or something
>>> similar?
>>>
>>
>> This is the use case for gluster volume shared storage - where volume is
>> a replica 3. If any host goes down, the data is available on the remaining
>> 2 nodes, and the VMs can be migrated to other nodes.
>>
>> Yes, I know, but I'm already worried about corruption issues due to
>> possible gluster bugs or performance problems under heavy load.
>>
>> I don't think what you ask for is possible automatically. If you want
>> local storage to gluster volume backup, you would need 1-1 mapping. i.e
>> each local storage domain has its own gluster volume backup.You could then
>> import the storage domain that's backed up on the gluster volume and start
>> the VMs on the remaining hosts.
>>
>> I don't want local storage for backup, I prefer gluster shared storage
>> for backup.
>>
>>
>>> Making backup with the import-export procedure based on snapshot can
>>> take lot of time and resources. Incremental rsync is cheaper in terms of
>>> resources.
>>>
>>
>> Geo-replication based backup internally uses rsync, it also takes into
>> account that VM images are consistent on disk before being synced. It
>> however works as a backup option between two gluster volumes.
>>
>> Do you know if is it possible to have multiple masters geo-replicating
>> against a single slave?
>>
>
> No it is not possible. A master can have multiple slaves not the other way
> around.
>
>
>>
>> Thanks a lot.
>>
>
>
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