[Sheepdog] Sheepdog cluster expansion

[MORITA Kazutaka]

At Mon, 1 Aug 2011 08:44:15 +0000,
Fernando Frediani (Qube) wrote:
> 
> Hi,
> 
> If I start my cluster with the following scenario: 2 Servers with 10TB each (one single logic drive presented by the Raid controller) and obviously copies=2 how should I grow it ?
> 
> Should I always add a 2 x Servers of 10TB every time I need to increase my storage or can I just do one by one and it will always balance the data between any number of servers available ?

You can add one by one.  The data will be balanced automatically
without any configuration.

> 
> If I can add one by one does these servers need always to be the exactly same size of others (10TB) or there is some flexibility on having a mixture of that and again the things will balance fine ?

Sheepdog assumes that all the disks have the same free space, so the
data will be balanced uniformly even if there is a much larger disk.
It is not impossible to handle different sized disks, but it is one of
the future works.

> 
> In another slightly different scenario if I have already enough storage for my KVM Virtual Machines and all I need is just CPU and Memory is it OK jus to add a node with that but without storage and make it use the sheepdog for its VMs as well ?

Basically, Sheepdog needs a local disk to use for a storage system.
Though your VMs can connect to the other machine from out side of
Sheepdog, in that case the connected server (gateway) could be a
single point of failure.  The connection failover is also one of TODO
items.

Thanks,

Kazutaka