[ovirt-users] Sizing the master storage domain

[Itamar Heim]

On 09/18/2014 02:32 PM, Nicolas Ecarnot wrote:
> Le 18/09/2014 13:30, Itamar Heim a écrit :
>> On 09/18/2014 02:27 PM, Nicolas Ecarnot wrote:
>>> Hi,
>>>
>>> I know Itamar explained that the notion of master storage domain will
>>> disappear in some releases.
>>> But now, with a 3.4 I'm installing, I was wondering :
>>>
>>> - on my other oVirt setups, I started with one big (iSCSI) LUN, which is
>>> the master, and stored as many VMs I could
>>> - when space came to miss, I added another LUN, the another...
>>> - when I have to do some maintenance (grow, disable, other...) on a LUN,
>>> I can move my VM disks amongst the normal storage domains. When Empty, I
>>> can switch them off, add others, and so on
>>>
>>> The only one I can not play with is the master one.
>>> I came to think that I had no benefice storing anything on the master
>>> storage domain, and use only the normal storage domains.
>>>
>>> And then, I came to think I had no reason to dedicate a huge LUN for the
>>> master.
>>>
>>> Ok, but according to you, what is the minimum reasonable size for a
>>> master storage domain?
>>>
>>
>> you should be able to move master domain to maint (deactivate, not
>> detach) as well (full or empty). engine will just configure another
>> storage domain as master iirc.
>
> This is a nice feature, but as detaching (then removing) is needed, my
> question still remains.
>

master storage domains is a normal storage domain. it only happens to be 
using its "special metadata part" as the master. so all storage domains 
have it. if its down, engine will automatically select another one.
iirc, we need 2GB for meta data (on block storage. NFS is allocated as 
needed).
iirc, we block or warn on creating storage domains of <10GB.