Support real HA Cluster with GFS and multiple Locations

Latest response

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!

Greetings

Jens Kühnel

RHCE (since RH62), RHCSS, RHCA#8
 

Responses

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:
http://people.redhat.com/ccaulfie/docs/CSNetworking.pdf

Hi,

 

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.

 

CU

Jens

Hopefully this KBASE will help explain supportability of stretch clusters:

 

https://access.redhat.com/kb/docs/DOC-61218

 

"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!

 

Regards,

 

Andrius

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.

Hi,

 

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).

 

CU

Jens

 

RHCA#8