best practices in using shared storage for XEN Virtual Machines and auto-failover?

Hi all,

Can anyone pleas tell me what would be best practice to use shared storage with virtual machines, especially when it involved high availability / automated failover between 2 XEN servers?

i.e. if I setup 2x identical XEN servers, each with say 16GB RAM, 4x 1GB NIC’s, etc. Then I need the xen domU’s to auto failover between the 2 servers if either goes down (hardware failure / overload / kernel updates / etc).

What is the best way to connect a NAS / SAN to these 2 servers for this kind of setup to work flawlessly? And, especially how do I make it work with CloudMin’s auto failover?

The NAS can export iSCSI, NFS, SMB, etc. I’m sure I could even use ATAOE if needed

Can anyone help me with this please?

Hi SoftDUx,

First rule of high availability is : planning !!!

Just my two cents…

If you want to setup high availability, you should:

  • Decided whether to have an Active - Passive or Active - Active implementation
  • charge each node no more than 50% of capacity, when having an Active - Active implementation
  • Decide the fileystem replication type and access in either case:
    –> DRDB - RAID 1 like implementation is very good for Active - Passive implementations not using a Shared Storage
    –> Using iSCSI, AOE, GFS2, OCFS2, dependes of couse, on the number of nodes that you decided to add to the structure presently and in the future, Specially in Active - Active situations.

I wonder if you are thinking to use OpenFiler for the NAS. Remember that NAS is quite different from a SAN implementation!

I do believe you could add to the fstab file, a mount point for the shared volume on both systems, pointing it to the same place, like “/xen”.

Don’t forget to separete LAN’s for Public/private accessm and another for Data Access ( NAS / SAN). Otherwise, you may get some bad performance values. If you go to AOE, adopt Jumbo Frames for the SAN network, it will boost your performance.