VMWare with 2 SAN, best redundant strategy

Posted on 2009-02-10
Last Modified: 2012-08-13

Im going to setup a VMWare farm with 4 VMWare Enterprise servers. I have 4 physical servers and 2 physical SANs.
My question is:

- Is it possible to make VM machines runs on 2 SANs simultaneously ? If 1 SAN failed then the other SAN will take over?
- What is best redundant strategy do you suggest to utilize 2 physical SANs ?

Thank you.
Question by:yowcsa
    LVL 21

    Accepted Solution

    No you cannot have a VM run off two SANs simultaneously. What you can do is have snapshot your VMFS volume(s) from SAN(1) to SAN(2) to have a backup copy of your VM's. However, the point of VMWare ESX with SAN is that you can use features like VMOTION and HA to ensure that your VM's are always up and running if a host fails. If your SAN fails, then other options need to looked at.
    In this case, you could use VMWare vCenter Site Recovery Manager to 'fail over' to your second SAN since I would class a failure of a SAN as a Disaster!
    But really this does depend on what type of SANS you have and your infrastructure.
    LVL 1

    Expert Comment

    Exactly what I was going to say...user your extra hardware for a test environemtn or DR/BC.
    LVL 3

    Assisted Solution

    On the surface this is an easy question, however when you start to think about it you are looking at a complex thing. SRM is the way to go in this situation as long as your SAN's are able to replicate to one another AND your SAN's are supported by SRM's SRA (Storage Recovery Adapter)

    Really the question is what is your goal? Utilize both SAN's in production due to space IO concerns? or provide failover and redundency? As long as space and IO are not tight SRM as noted above is the right answer.

    Author Comment

    We have 2 buildings (500m distance)  and 2 DELL CX4 SANs, my main goal is if 1 SANs suddently die the other SANs will automatically take over and the systems keep on running.

    What is your suggestion for best redundant strategy to utilize 2 physical SANs ?
    LVL 21

    Assisted Solution

    Well we have a similar setup where we have two SAN's in two buildings.
    Each one data volumes is replicated to the other. Our solution is nearly fully redundant i.e. two Fabrics, etc, etc. The configuration is such that there is an active Path (ESX Server A connected to SAN A in Building A) but it also has a redundant path to the same LUN's etc being hosted on SAN B in Building B via Fabric B so if SAN A fails, it will automatically fail over to SAN B.
    Of course both SAN A and SAN B are replicating to each other. You will need to consult you SAN documentation or your SAN Vendor on how you would configure that.
    So yes it is possible in that scenario without needing SRM, etc.
    LVL 18

    Expert Comment

    500m is not so far away and it would be possible to use setup a mirror with some SAN virtualization software in front in order to automatically use the live site and sync back once it's up again.

    Solutions that can do this include DataCore SanSymphony/SanMelody, IBM SVC, EMC InVista, FalconStor &  LeftHand.


    LVL 3

    Expert Comment

    Datacore sanmelody does this.  We have three Esx boxes and two datacore sanmelody in synchronous MPIO via ISCSI.  One Datacore San is considered the primary, the other the secondary.  If either SanMelody server goes down the other keeps on going.  Though if the primary goes down unexpectedly sql servers and exchange complain for about a second.  We have two buildings about 2 miles apart, we put 10g  fiber between the two.  We placed one of the ESX boxes and one of the datacore sans in the other building and vlan'ed the iscsi over the fiber.  We can vmotion between all three esx boxes /both buildings and datacore sanmelody works fine synchronous between both buildings.  In my tests it took longer to drive to the other building then it did to get things back online.  We also setup a asynchronous datacore server in a third building for extra backup

    Featured Post

    What Should I Do With This Threat Intelligence?

    Are you wondering if you actually need threat intelligence? The answer is yes. We explain the basics for creating useful threat intelligence.

    Join & Write a Comment

    Suggested Solutions

    It Is not possible to enable LLDP in vSwitch(at least is not supported by VMware), so in this article we will enable this, and also go trough how to enabled CDP and how to get this information in vSwitches and also in vDS.
    David Varnum recently wrote up his impressions of PRTG, based on a presentation by my colleague Christian at Tech Field Day at VMworld in Barcelona. Thanks David, for your detailed and honest evaluation!
    Teach the user how to use configure the vCenter Server storage filters Open vSphere Web Client:  Navigate to vCenter Server Advanced Settings: Add the four vCenter Server storage filters: Review the advanced settings: Modify the values of the four v…
    This video shows you how to use a vSphere client to connect to your ESX host as the root user. Demonstrates the basic connection of bypassing certification set up. Demonstrates how to access the traditional view to begin managing your virtual mac…

    746 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    18 Experts available now in Live!

    Get 1:1 Help Now