[Glass] [GS/SS Beta] Scale to multiple nodes sharing a DB?

[James Foster]

On Nov 28, 2013, at 7:57 PM, Mariano Martinez Peck <marianopeck at gmail.com> wrote:

> On Thu, Nov 14, 2013 at 9:05 PM, Dale K. Henrichs <dale.henrichs at gemtalksystems.com> wrote:
> Bruno,
> 
> The short answer is yes:)
> 
> Mutiple stones can be run on a single host.
> 
> The following questions are outside GLASS, I know. Also, note that I already understand I can have many gems running in other nodes. 
> 
> Ok, but are they "isolated" stones each with its own repository?  

Yes, each stone is associated with only one repository.

> Or I can have many stores (I refer to the process running the store) running/sharing the same repository?
> My question in other words is...if the stone is finally the bottleneck, could we have many stores running in many nodes sharing the same repository (object graph)?

No, the stone is a possible bottleneck because it handles things that are necessarily single-threaded, such as allocating object IDs, page IDs, object locks, the commit token, etc. In actuality, the stone is rarely a bottleneck. You are much more likely to have problems with writing to the transaction logs before you have problems with the stone. For more discussion about the stone see http://www.youtube.com/watch?v=NAW7OkjXZ0M. 

> If not in different nodes, at least can I run many stones processes in the same node?

As Dale says above, multiple stones (with separate repositories) can run on a single host.

> Not only for scalability but about fail tolerance. What if somehow the stone is down? 

This is where you want a good standby. See chapter 10 of the System Administration Guide.

James


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