[DRBD-user] Adding a third node

Aaron Johnson aaronjohnson at ajserver.com
Fri Sep 27 19:26:32 CEST 2013

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


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.


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;
>         }
>         on kvm-srv-02 {
>             address;
>         }
> }
> 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;
>    }
>    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
> paul at tracker-software.com <mailto:paul.ororke at tracker-software.com>
> 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<ls at numerigraphe.com>  wrote:
>>> Le 25/09/2013 08:10,roberto.fastec at gmail.com  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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>>> drbd-user at lists.linbit.com
>>> http://lists.linbit.com/mailman/listinfo/drbd-user
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