Paul,

That config looks right, however you will want to use a VIP address instead of the IP address of just 1 node. This IP will move between the 2 local nodes to whichever node is active, otherwise if when the node with the IP in the local resource is down you will not get updates to the stacked offsite node.

Also be aware of private vs. public IP space and how the IPs may appear when NAT comes into play and which IPs need to appear where in the config. I avoid this by having my 2 locations connected by VPN so all addresses are direct, no NAT.

Aaron



On 9/26/2013 4:06 PM, Paul O'Rorke wrote:
Thanks for that Aaron,

I'm looking at this page http://www.drbd.org/users-guide/s-three-nodes.html and not quite sure I understand how to merge this with my current config. Currently I have 5 resources using Protocol C on my 2 node local cluster.

For the sake of this set up I will consider the set up one of these resources with a third node using a stacked resource and protocol A then hopefully once that is working I can apply this to the other resources.

In the example provided it appears that I need to define all three resources in the one .res file. I have the following 2 config files:

*/etc/drbd.d/global_common.conf*
global {
        usage-count yes;
}
common {
        protocol C;
}

and

*/etc/drbd.d/restored.res*
resource restored {
        device    /dev/drbd2;
        disk        /dev/VirtualMachines/restored;
        meta-disk internal;
        on kvm-srv-01 {
            address 192.168.2.41:7789;
        }
        on kvm-srv-02 {
            address 192.168.2.42:7789;
        }
}


can I just tack something like this onto the end of */etc/drbd.d/restored.res*?

resource restored-U {
   net {
     protocol A;
   }

   stacked-on-top-of restored {
     device     /dev/drbd10;
     address    192.168.3.41:7788;
   }

   on buckingham {
     device     /dev/drbd10;
     disk       /dev/hda6;
     address    <fixed IP at backup node>:7788; # Public IP of the backup node
     meta-disk  internal;
   }
}

I am also wondering, since I have a spare NIC on my local nodes, would I be better to use that to connect to my off site resource or use the LAN connected NIC? In the example above I used a different subnet for the off site and called the off site machine 'buckingham'.

I hope my question makes sense, still finding my feet here.

Please and thanks

*Paul O’Rorke*
Tracker Software Products
[email protected] <mailto:[email protected]>

On 9/25/2013 2:21 PM, Aaron Johnson wrote:
Yes you can add the stacked resource later, I have done this same thing several 
times now by making the the device slightly larger first and using internal 
metadata.

Also I have a DR site using protocol C and pull-ahead enabled without using 
DRBD proxy.  The main site and DR site are connected via cable modem 
connections (10Mbit up/ 20 down both sides).  The only thing I have troubles 
with is if I need to add a large amount of data (50+ GB), which in my case is 
fairly rare (daily norm is ~2GB), then it can take days or weeks to sync up 
fully again.  Also I used truck-based updates for the initial setup of ~1TB to 
avoid having to pull all that over the internet link.

Thanks,
AJ

On Sep 25, 2013, at 7:54 AM, Lionel Sausin<[email protected]>  wrote:

Le 25/09/2013 08:10,[email protected]  a écrit :
The purpose you are talking about, sounds more as the purpose DRBD Proxy has 
been developed for

www.linbit.com/en/products-and-services/drbd-proxy
Yes and no, my understanding is that DRBD-proxy lets your production cluster 
run faster than the connection speed by acting like a write cache.
But if I'm not mistaken you still need a stacked configuration for 3 node 
setups until v9.0 is released.
Someone please correct me if that's wrong of course.

Lionel Sausin
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