Support real HA Cluster with GFS and multiple Locations

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Dear RedHat,

I was surprised to learn the Redhat doesn't have a real High Availability solution.

RHEL with HA (Cluter) and Resilient Storage (GFS) - Add on are only supported if it is in the same data center aka. not-stretched cluster.

High Availability is the elimination of single point of failures and everything in one data center is exactly that.

Especially because I don't see a technical reason for that.

It would be nice to see RHEL7 playing with the big boys!


Jens Kühnel

RHCE (since RH62), RHCSS, RHCA#8


cman supports multicast and can be used across routers/network boundaries if properly configured.

This is discussed in detail in an excellent Red Hat whitepaper written by Christine Caulfield:



RedHat Support / TAM  told me something else. It may work, but it is not supported.


The problem is storage. You can use cluster, but without CLVM and GFS. aka only as a standby cluster.




Hopefully this KBASE will help explain supportability of stretch clusters:


"Stretch clusters (ie. clusters in separate physical locations connected over a long distance) require special reviews to ensure that their design is within the limits of Red Hat Cluster Suite."


Therefore, full support for a stretch cluster would first need to be reviewed via an Architecture Review by Red Hat Support and Red Hat Engineering.


Hope this helps!





Red Hat, Inc.

The mentioned doc says:

"Red Hat Clustering is designed to run at a single physical site where latencies are expected to be LAN-like (about 2 msec)."

Ouch. That'll be a little embarassing to admit to my colleagues on Solaris/AIX.



I read all the pages you are pointing to, but at the end RedHat Support (our TAM) told us:


in stretch cluster configurations, GFS, GFS2, CLVM, and cmirror are not supported.


Yes, we are under 2 ms. But still it is not supported.


If someone from RedHat reads that. Please review Case# 00502183 (we had to switch to NFSv4).