[DRBD-user] drbd 0.8 primary/primary limit question

[Paul Court]

>   Current project is asking for a clustered file system to be used in a 
> small web farm.  Unfortunately, NFS is not an option at this point, for 
> budget constraints... small client...

Do you really need a cluster filesystem for a web farm? Would it not 
make life a lot simpler to just rsync the web content periodically?

>   Researching alternative options... and seeing DRBD primary/primary 
> option with OCFS2 as a feasible alternative.
> 
>   Question...  You can only have 2 primary/primary nodes in such setup, 
> correct?  In my case, if I got a 3rd web server, client would have to 
> procure a NAS...

You could just run normal primary/secondary on two nodes and share the 
drbd volume (or parts of it) using NFS and heartbeat. There is no need 
for a separate NAS appliance.

If you really want to use DRBD across three nodes then the commercial 
version (DRBD+) can mirror across 3 nodes - I am not sure if that is 
primary/primary/primary though.