Connecting to a SAN from multiple hosts

Posted on 2011-05-02
Last Modified: 2013-11-08
We have an IBM DS3512 SAN device connected via SAS to (2) IBM x3550 M3 servers. The x3550 servers are running Server 2008 R2 DataCenter edition in Server Core mode. We are going to use these as Hyper-V hosts, with the VM guests residing on the shared SAN. I am able to see the SAN from both servers, by remotely connecting into Server Manager. I can drill down into Storage Manager for SANs and using LUN Management - I am able to see the LUN, as well as assign the volume a drive letter in Disk Management. The (2) IBM x3550 hosts are NOT clustered.

I want to be able to mirror this information on both hosts, so either x3550 Hyper-V host can manage the VM guest on the SAN. Right now, if I assign the SAN volume a drive letter and create files/folders, they are not visible to the other host. Each host is managing the LUN separately.

How can I make it so both hosts see the same volume?
Question by:WPI Help
    LVL 2

    Expert Comment

    Jay...Assuming I know what your goal is...

    I would Think about putting the Servers in a cluster, and sharing the Storage point.  If this were a vmWare gig, I'd say cluster the host servers, use iSCSI to find the SAN in the Client, and Create your shared Resource Pools as you need them for the long run.  Same is possible with Hyper-V, and I'm a bit puzzled even why you would mirror the hosts, instead of leveraging the power of each server as a part of a cluster?

    Bear in mind, I don't know the RAID setup on the SAN, or why there is only one Volume, etc...etc...feel free to contact me if you think I might be able to help further.
    LVL 14

    Assisted Solution

    See if this document will help you: Hyper-V: Using Hyper-V and Failover Clustering
    LVL 1

    Expert Comment

    by:Patrick Nunez
    First you need to set up a shared LUN on your SAN that both x3550's can see.  Next you need to install the Failover Cluster component of DataCenter.  Lastly, you need to set up a Cluster Shared Volume.  The Hyper-V's that you want to failover will live on the Cluster Shared Volume.  

    Take a look at this article for more information:

    Good luck and keep us posted on your project.

    Author Comment

    by:WPI Help
    Thank you everyone for the responses. Just to recap: Our goal is to use this configuration as a Hyper-V environment, with both hosts able to manage the VMs residing on the shared SAN. The SAN is connected via SAS connections to the (2) IBM x3550 servers, which are running Server 2008 R2 datacenter edition (Server Core mode). We will use VMM to manage the VMs on both hosts and we want to be able to migrate VMs between the two hosts.

    After I posted this, I started looking into Failover Cluster. I was able to configure this and (I think) succesfully implement this for both nodes. In the Failover Cluster Manager - I can see the newly created Cluster with both nodes listed as "UP". There is no storage showing up under Cluster Shared Volumes and it will not let me add storage as it gives me the error: "There are no available disks in the cluster". I do however have a Cluster Disk volume showing in the "Disk Witness in Quorum" under Storage options. This is the single 1 TB LUN I created on the IBM SAN (RAID 10 btw) through IBM's DS Storage Manager, adding both hosts to a Host Group.

    For Hyper-V configurations using 2-nodes w/ shared SAN - is there a different way to setup High Availability or am I on the right track? Are there other recommended configurations, to make sure we are maximizing the server resources, yet making it easy enough for us to manage/migrate guest VMs as needed? Any other recommendations/suggestions I should be aware of with this config?

    Thanks again everyone.
    LVL 41

    Assisted Solution

    You are now on the right track. You need to have at least two LUNs: one for disk quorum (I use 100 GB thin provisioned, I think it can be a lot smaller but I haven't experimented to see how small it can be), and then one or more volumes for storing your VMs. Add a new LUN and reconfigure quorum to use that smaller disk. You should them be able to make the larger disk a CSV for your VMs. The larger volume should be formatted NTFS 64K cluster size for storing VHDs.
    LVL 38

    Accepted Solution

    If dual or more SAS connections between node and storage make sure to enable and configure MPIO.

    Create your storage in you DS3512.

    On node 1 for each LUN created above:
     Intialize, format and name, and set to OFFLINE.
    On node 2:
     ReScan disks (cancel Initialize request).
     Set to Offline.

    In Failover Cluster Management (or whatever you are using) ADD Storage.
    Add the disks.

    Make sure to enable Clustered Shared Volumes.
    Add Storage to CSV.
    Make sure to have BOTH Hyper-V server's VM Settings pointing to c:\clusterstorage\volumeX (whatver LUN you designate for your common settings files and memory files).


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