[DRBD-user] can't mount on secondary node
Martin Gerhard Loschwitz
martin.loschwitz at hastexo.com
Wed Feb 1 14:34:42 CET 2012
> 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
> > 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.
Please note that there are other ISPs that do this as well, and there are
solutions for this in place. Like for Hetzner:
I've personally set this up already, and it did work nicely. Maybe they
can help you, too. Maybe you can adopt this to work for your provider.
> Otherwise, you can set up Pacemaker + Fencing + OCFS2 + Dual-Primary and
> get away without promotions. But it's more challenging.
NO. NO. NO. NOOOOOOOOOOO.
NO NO NO NO. NO. NO.
I'll say it again: Every time somebody recommends to use Pacemaker with
OCFS2, god kills a kitten. So people, please please please only and
really only recommend OCFS2 (or GFS) when there are good reasons for it.
All the little kittens that survive will be really thankful!
I hardly think that this is a valid OCFS2 usage scenario, quite frankly.
No offense meant, but introducing another level of complexity in this
setup won't do any good.
Martin Gerhard Loschwitz
Chief Brand Officer, Principal Consultant
hastexo Professional Services
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