[ClusterLabs] NFS in different subnets

Daniel Smith Daniel.Smith at craneww.com
Fri Apr 17 15:20:04 EDT 2020

Thank you digimer, and I apologize for getting the wrong email.

Booth was the piece I was missing.  Have been researching setting that up and finding a third location for quorum. From what I have found, I believe I will need to setup single node pacemaker clusters at each datacenter to use with booth. Since we have ESX clusters at each site which has its own redundancies built in, building redundant nodes at each site is pretty much a waste of resources imho. I have 2 questions about this setup though:

1.       If I setup pacemaker with a single node an no virtual IP, is there any problems I need to be aware of?

2.       Is drbd the best tool for the data sync between the sites? I've looked at drbd proxy, but I get the sense that it's not open source, or would rsync with incrond be a better option?

I already made a script that executes with the network startup that updates DNS using nsupdate so that should be easy to create a resource based on it I would think.

From: Digimer [mailto:lists at alteeve.ca]
Sent: Friday, April 17, 2020 11:01 AM
To: Daniel Smith <Daniel.Smith at craneww.com>; Cluster Labs - Users <users at clusterlabs.org>
Subject: Re: NFS in different subnets

EXTERNAL SENDER: Use caution with links/attachments.

Hi Daniel,

  You sent this to clusterlabs owners, instead of users. I've changed the CC to send it to the list for a larger discussion.

  The biggest problem with stretch clustering is knowing the difference between a link fault and a site loss. Pacemaker Booth was designed to solve this problem by using a "cluster of clusters". The logic being that if a site is lost, an arbiter node at a third site can decide which site should live, and trust the lost side will either behave sensibly (because it is itself a cluster), or it's destroyed.

  After this, it just becomes a question of implementation details. Have the master side update a DNS entry should be fine (though you may need to write a small resource agent to do it, not sure if one exists for DNS yet).

On 2020-04-17 11:44 a.m., Daniel Smith wrote:
I have been searching how to customize pacemaker to manage NFS servers in separate datacenters, but I am finding older data that suggests this is a bad idea and not much information about how to customize it to do this without the 1 IP being moved back and forth. If this isn't the best tool, please let me know, but here is the setup I am trying to do if someone can help point me to some information on how the best way is to do this.

Server 1:              DC01-NFS01,<https://urldefense.proofpoint.com/v2/url?u=http-3A__10.0.1.10_24&d=DwQF-g&c=Wu-45Ur27gGDpxsjlug4Cg&r=q-8ZpsKaCLRx2o0mEXxy3Wwikv-bFgowvCmzCB6rH1g&m=55Uvz_i91WnbPX2YcZy4D8fuOxfKaswxUUQOUE8_3OM&s=KgYE6g5eRefvMqaVB3DF6zJehnQckYcqsjgq7F87OAw&e=>
Server 2:              DC02-NFS01,<https://urldefense.proofpoint.com/v2/url?u=http-3A__10.0.2.10_24&d=DwQF-g&c=Wu-45Ur27gGDpxsjlug4Cg&r=q-8ZpsKaCLRx2o0mEXxy3Wwikv-bFgowvCmzCB6rH1g&m=55Uvz_i91WnbPX2YcZy4D8fuOxfKaswxUUQOUE8_3OM&s=5DLmpw3KoLmznfpizJa1N-QMNJnZ6_uoiXbDs6kZETM&e=>
NFS share:           nfs01.domain.local:/opt/nfsmounts using drbd to sync between datacenters
DC01 to DC02 has a 2Gb layer 2 connection between the datacenters

I would like to have pacemaker manage the NFS services on both systems in an active/passive setup where it updates the DNS servers with the active server's IP for nfs01.domain.local. Eventually, we will have a virtual switch in VMWare that I would like pacemaker to update, but for now, the delay in DNS updates will be acceptable for failover.

Thank you in advance for any help you can provide.

Daniel Smith
Network Engineer
15894 Diplomatic Plaza Dr | Houston, TX 77032
P: 281-233-8487 | M: 832-301-1087
Daniel.Smith at craneww.com<mailto:Daniel.Smith at craneww.com>
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