How to Configure and Maintain High Availability/Clustering in Linux

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Aaron Kili

Aaron Kili is a Linux and F.O.S.S enthusiast, an upcoming Linux SysAdmin, web developer, and currently a content creator for TecMint who loves working with computers and strongly believes in sharing knowledge.

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14 Responses

  1. Mokhtar says:

    I’ve problem with starting the corosync & pacemaker services.

    Please check the snapshot below.
    https://imgur.com/a/Xhaf5pn

  2. PC says:

    Thank you for this tutorial. I have a setup with a gateway configured with 2 interfaces eth0 with 10 public IP addresses, and eth1 with a local IP (10.0.0.1) address. I am then using iptables for nat, and nginx working as a reverse proxy.

    Behind this, I have multiple servers running different services all with the network 10.0.0.x and using the 10.0.0.1 as a gateway. I need to add a secondary gateway as a failover, as the datacenter its a 4h drive. If one of the gateways dies, the other one will move the 10 public IP addresses and one local to the other gateway.

    Can this be done using this configuration? Can I have the multi public IPs and a local one floating from one server to the other? Any help will be appreciated.

  3. ariuan says:

    Can I use public IP for the cluster IP address while server IP maintain private?

  4. Ievgen says:

    I see it is not a balanced approach.
    Is it possible to create balanced with round-robin rule for example?

    • Aaron Kili says:

      @Ievgen

      Sure, this is a basic setup for beginners to get started with HA, we will work on advanced setups in the future, and possibly cover the approach you are recommending. Thanks for the feedback.

  5. Saiful Islam ROkon AKon says:

    Hi,

    I have followed all step, but I can’t connect with my second node.

    Error: Unable to communicate with node2.example.com

    How can I resolve?

    Anyone please suggest me.

  6. John says:

    Any idea how to get this running on virtualbox? I did all the steps, but can’t access the nginx server.

  7. Matt K says:

    Also, you don’t want services controller by Pacemaker to start at boot. Pacemaker is the only thing that should be starting/stopping services.

  8. Matt K says:

    Without collocation constraints your VIP and WWW server will end up on different nodes. Also, where’s the replicated storage? DRBD is open source, ships with Ubuntu, and is easy to setup so maybe that’s an easy add.

    One more thing about STONITH: stop operation failures will leave you dead in the water without it, but the setup is very particular to your environment, so I would leave that as an exercise for the reader too. Add proper constraints and something for replication and this is a good primer!

    • Aaron Kili says:

      @Matt

      We will do a little research on collocation constraints and update the guide to include them. We are working on a separate guide for DRBD, which we will link to this guide. Thanks a ton for sharing this useful feedback.

  9. steve cohen says:

    The main problem is that this approach does not take into account the state of application programs. If you are using an oracle database service, oracle does back itself up automatically. also even nfs files do not back themselves up.

    A far better test of high availability is to just turn off one cluster and see what happens. If the ip address changes, and the mount occurs from one system to the other good. Now you have to have a way of journeling everything run on a server. that way when if fails you can run the journal on the disk to get it all back.

    • Aaron Kili says:

      @steve

      Many thanks for the useful additions, as we mentioned at the start of the guide, this is a basic setup to get started with high availability and clustering in Linux. One can always read the full documentation of the mentioned applications, to setup a better production-level HA/clustering environment.

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