GFS active-active on host-based SAN Mirror

Latest response

 

Hello,

 

I am looking for a solution description to bring online a dual primary gfs2 cluster which stores data on a SAN. In Addition the SAN should be mirrored by Host to a second SAN for HOT Switchover by SAN outage.

 

I hope anybody can helps me?

 

Regards

Thomas

Responses

Hi Thomas!

 

It sounds to me like you are trying to set up the following:

  • 2 Node Cluster
  • Shared GFS2 Storage
  • Active/Active use-case (i.e. both nodes accessing GFS2 at the same time)
  • Redundant SANs housing GFS2

Here's some informatation that may help you out:

 

Setting up a 2 node cluster for the first time (RHEL 6):

https://access.redhat.com/knowledge/solutions/63671

 

Setting up a 2 node cluster for the first time (RHEL 5):

https://access.redhat.com/knowledge/solutions/59173

 

An Active/Active cluster (what I assume you mean when you say "dual primary") is simply a matter of having both nodes run services at the same time and having GFS2 mounted on both nodes at the same time. For most workloads that should be no big deal, but if you are doing anything with NFS, Samba, or highly active workloads (lots of deletes and file creates) you may want to contact Red Hat Support to ensure that your use case is going to work out OK,

 

As far as the redundant SANs though you can do that a couple of different ways. If your SANs support replicationon the backend then you don't have to do anything special on the OS side other than set up Device Mapper Multipath to ensure that the OS will use paths from whatever SAN is operational at the time. If you want the OS to manage replication between the SANs then you are looking at using CLVM+Cmirror to mirror physical volumes:

 

How to create a clustered LVM stack:

https://access.redhat.com/knowledge/solutions/121723

 

How to mirror a clustered LVM stack:

https://access.redhat.com/knowledge/solutions/21046

 

Note: If your SANs are located at different sites (i.e. a DR type situation) you should contact Red Hat Support to ensure that your config is going to work. There are some caveats around GFS2 + mirroring + multi-site deploys.

 

Finally, as always, make sure to give the offical product docs a good read. They can usually answer any questions you come up with:

https://access.redhat.com/knowledge/docs/Red_Hat_Enterprise_Linux/

 

(If you search on that page for "High Availability", "Logical Volume" "Global Filesystem" and "Cluster" you'll see the docs I'm talking about.)

 

Thanks and good luck!

Adam