[DRBD-user] can't mount on secondary node

Felix Frank ff at mpexnet.de
Wed Feb 1 13:19:05 CET 2012

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


Hi Lawrence,

please be careful to CC the list (everyone's hearing half a conversation
otherwise ;-)

On 02/01/2012 12:38 PM, Lawrence Strydom wrote:
> Hi Felix.
> 
> My setup is, supposed to be, fairly straightforward.  Two web servers,
> one in production and the second as a hot standby.
> The problem comes in with availabillity of IP addresses though. These
> are hosted servers and the hosting company won't provide more than one
> Live IP per machine. This means I can't use a floating virtual IP which
> fails over to the second node as that would require a third live IP.

You could send node1's IP floating and remove node2's public IP. Add
internal IPs to both machines, so the passive node is reachable by
hopping through the one with the public IP.

Unless, of course, there are network policies in place that forbid such
shenanigans.

> Instead the hosting company provides fail over of the real IP of the
> primary server to the secondary server through their control panel.
> Weird I know but I didn't choose them, just got given the job.  Ok so
> now I need data to be synchronous over both servers in case of primary
> node failure so dual primary would make sense as the IP fail over is
> already taken care of and no further action will be required to make the
> data available on the secondary node.

Fair enough. So the answer would probably still be the same: Do use
pacemaker. The easier way will be to just manage DRBD+Apache, or even
DRBD only. However, the production node is selected independently from
pacemaker, which makes for an odd (and error-prone) design.

Otherwise, you can set up Pacemaker + Fencing + OCFS2 + Dual-Primary and
get away without promotions. But it's more challenging.

HTH,
Felix



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