[DRBD-user] Three node setup questions

David.Livingstone at cn.ca David.Livingstone at cn.ca
Wed Feb 18 23:44:15 CET 2009

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


Lars,

Thanks for the reply. See below.

> On Tue, Feb 17, 2009 at 03:52:16PM -0700, David.Livingstone at cn.ca wrote:
> > Hello,
> >
> > I currently have two two-node clusters running heartbeat and drbd(see
> > background below). I also have a two-node test which I decided to 
update
> > to the latest releases of all. In so doing I downloaded and installed
> > drbd 8.3.0(drbd-8.3.0.tar.gz) which includes three-node setups using
> > stacked clusters. Specifically havng a third backup/brp node
> > geograghically removed from our production cluster is very appealing.
> >
> > I have looked at the online manual(http://www.drbd.org/users-guide/)
> > and read the current information for three-node setups and have some
> > observations/questions :
> > - An illustraion/figure of a three-node setup would help.

> there are several ways to to it.
> you can also have four nodes: two two-node DRBD, the primary of which is
> the "lower" resource of a "stacked" DRBD.

Are there some examples I can review somewhere ?

> > - From your "Creating a three-node setup" example on which machine 
does
> > the stacked-on-top-of address run(ie 192.168.42.1) ?

> IP should be managed by heartbeat/pacemaker.  it needs to be present
> before you promote the "upper" resource to Primary.

> > In my case my third
> > node is not on the same ip segment as my two other nodes.

> no matter.

So in the "Creating a three-node setup" the ip would only ever be assigned
to resource r0 nodes(alice or bob). Correct ?

> > - After doing some searching I hit on the http://drbd-plus.linbit.com
> > page which mentions configuraion keywords "ignore-on" and "use-csums".
> > Neither of these exist in the drbd.conf man page. Are they needed ?

> solved differently.
> ignore-on was not flexible enough, so it was dropped.
> use-csums has been replaced with csums-alg (so you can chose the
> algorithm to be used for the checksum based resync).

okay

> > - The manual talks about the drbdupper resource used in R1 style
> > clusters. What about CRM style clusters ?

> "interessting" setups with "interessting" constraints.
> or use drbdupper resource anyways.
> We probably need a blog post or other feature about this.

That would be great. Any examples ? 

> > - In the R1 style configuraion you state :
> > "The third node, which is set aside from the Heartbeat cluster, will
> > have the other half of the stacked resource available permanently."
> > I presume by this you mean that if the two-node cluster disappears 
that
> > the mounting/application startup on the backup node is done manually ?

> more or less, yes.

> > Other Questions :
> > - Is the manual available for download/printing ?

> No. We hand it out in training sessions, though.

Vienna sounds good ... now if I could convince my boss ...

> > - Has anyone used the nx_lsa(Linx Sockets Acceration) driver to run 
drbd ?

> I'm not exactly sure what that is supposed to do.

See http://www.netxen.com/technology/pdfs/Netxen_LinuxSocketsAcc_r3.pdf
Essentially it implements a socket-level offload of the network subsystem 
to
a TCP stack running in firmware on the NIC. By using the nxoffload 
facility
you can specify tcp ip, ports or applications to offload.


> > Background :
> > 1. Current two-node production clusters :
> > - HW : - Proliant DL380G5
> > - Crossover for drbd : HP NC510C(NetXen) 10GB using nx_nic
> > - SW : - RHEL5 and kernel-PAE-2.6.18-92.1.10.el5
> > - drbd : drbd-8.2.6-3, drbd-km-2.6.18_92.1.10.el5PAE-8.2.6-3,
> > - heartbeat/pacemaker :
> > heartbeat-2.99.0-3.1
> > heartbeat-common-2.99.0-3.1
> > heartbeat-resources-2.99.0-3.1
> > pacemaker-heartbeat-0.6.6-17.2
> > pacemaker-pygui-1.4-5.1
> >
> > 1. Test two-node cluster :
> > - HW : - Proliant DL380G4
> > - SW : - Latest RHEL5 and kernel-2.6.18-128.1.1.el5
> > - drbd : drbd-8.3.0-3, drbd-km-2.6.18_128.1.1.el5-8.3.0-3
> > - heartbeat/pacemaker :
> > heartbeat-2.99.2-6.1.i386.rpm
> > heartbeat-common-2.99.2-6.1.i386.rpm
> > heartbeat-resources-2.99.2-6.1.i386.rpm
> > pacemaker-1.0.1-3.1.i386.rpm
> > pacemaker-pygui-1.4-11.9.i386.rpm
> >

> 
> --
> : Lars Ellenberg
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