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In my environment, I have a need for a shared disk between two application servers such that changes on Server A are immediately available on Server B. Historically, I have solved this issue by sharing a GFS2 volume by using multipathed disks stored on our enterprise filer and attached using our virtualization solution.

This configuration requires fencing of the GFS2 nodes in the cluster and so I have used pacemaker to handle the fencing for GFS2 in the event that a node dies or becomes unhealthy to prevent full corruption of the file system by configuring stonith to use SBD fencing previously.

While gfs2-utils and fence-agents-sbd is available for CentOS, the pcs command is not available as of CentOS 8.0 and it appears that it may never be available in the main repos. This is problematic as pcs was integral in configuring this in CentOS 7.

This leaves me wondering

  • What can I do as an alternate for fencing the volume without having to compile the applicaiton from source (ongoing security updates & bug fixes is a requirement)
  • If nothing, what can I use to provide a distributed & redundant storage solution in CentOS 8? An NFS server would be out of the question as a failure to the file server would take both application servers offline.
  • What about an HA NFS Cluster running on CentOS 7 (Pacemaker/Corosync/DRBD?). – Matt Kereczman Nov 19 at 20:58
  • @MattKereczman - Our enterprise filer is capable of serving a block device to an NFS server, but I do not know if it is able to support a DRBD configuration. – James Shewey Nov 19 at 21:39
  • @JamesShewey If it's serving a block device, you could have it serve block-device-a to node-a, and block-device-b to node-b, and use DRBD to replicate the data between them. Then, use Pacemaker/Corosync/DRBD to build a shared-nothing HA NFS cluster. – Matt Kereczman Nov 20 at 0:45
  • @MattKereczman - The goal here is to upgrade to CentOS 8. Deploying other CentOS 7 servers defeats the purpose. That only takes me as far as the CentOS/RHEL 7 end of life. – James Shewey Nov 20 at 4:04

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