[DRBD-user] see replicated data

Helmut Wollmersdorfer helmut.wollmersdorfer at fixpunkt.de
Thu May 31 15:51:19 CEST 2012

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

Am 31.05.2012 um 14:23 schrieb agag:

> My first idea is to have in example WWW server and when one crashes,  
> second
> is working without any additional admin tasks.

You can do this with a drbd-device as primary/secondary, mounted e.g.  
as /ha, and having your webspace, logs, configs etc. somewhere under / 
ha. Then configure pacemaker with IP-failover etc. and it works as  
long as one of the cluster-nodes is alive.

I had such a configuration since ~2004 with heartbeat and drbd-0.7.   
Disadvantage is, taht you need to take care of all dependencies like  
cron-jobs, webstats, users etc. and maybe need to modify some scripts.

> Second idea is to have almost identical operating systems. For  
> example to
> use drbd replicated data for /etc and /bin (wich will be modified  
> only in
> primary/first serverd when changes or updates are done). Is it  
> possible
> somehow?

You can use it for the whole / (root-filesystem), if you start an  
virtual machine on a drbd-device. That's most convenient as everything  
is replicated. It works in primary/secondary, with a downtime of  

Helmut Wollmersdorfer

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