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ISCSI Target Setup on Server 2012

    Question

  • I am looking for some information, documentation, best practices on setting up the Server 2012 ISCSI target, not the ISCSI target role installation as I have already done that. Specifically I am looking for information on setting up IP addressing on the ISCSI target and associated ISCSI initiators. Does the ISCSI target work as Active/Active on all NICs assigned to the target?

    I have a server setup with the ISCSI target that has 4 NICs dedicated to ISCSI. The ISCSI NICs are IP addressed as follows: 

    ISCSI-A-192.168.0.1 255.255.255.0
    ISCSI-B-192.168.0.2 255.255.255.0
    ISCSI-C-192.168.0.3 255.255.255.0
    ISCSI-D-192.168.0.4 255.255.255.0

    There are two hosts setup with MPIO and the ISCSI initiator to connect to the storage (for a Hyper-V failover cluster) each with two NICs for ISCSI as follows:

    HOST1-ISCSI-A-192.168.0.5 255.255.255.0
    HOST1-ISCSI-B-192.168.0.6 255.255.255.0

    HOST2-ISCSI-A-192.168.0.7 255.255.255.0
    HOST2-ISCSI-B-192.168.0.8 255.255.255.0


    Microsoft Partner

    Tuesday, August 21, 2012 8:36 AM

Answers

All replies

  • It depends on how you configure the MPIO on ISCSI initiator.

    By the way, it is recommended that you put those network adapters in different subnet.
    Wednesday, August 22, 2012 6:12 AM
  • You need to configure multipath and use round robin policy then all NICs will be used by target to serve requests @ the same time (if they overlap of course). Active/Active is a bit wrong term for this as generally it refers to ability to serve multiple requests from the different nodes / controllers. MS target can be configured to run HA but only Active/Passive (as a generic failover cluster app). For MPIO configuration please check these links:

    http://blogs.technet.com/b/migreene/archive/2009/08/29/3277914.aspx

    http://www.server-log.com/blog/2011/7/26/setting-up-an-microsoft-iscsi-target-and-initiator-using-mpi.html

    and for configuring MS target in failover mode these ones:

    http://technet.microsoft.com/en-us/library/gg232621(v=ws.10).aspx

    http://techontip.wordpress.com/2011/05/03/microsoft-iscsi-target-cluster-building-walkthrough/

    Hope this helped :)

    -nismo

    Wednesday, August 22, 2012 6:14 AM
  • It depends on how you configure the MPIO on ISCSI initiator.

    By the way, it is recommended that you put those network adapters in different subnet.

    Where is it recommended that the ISCSI adapters are in different subnets? In the link below that VR38DETT provided the config shows them on the same subnet:

    http://www.server-log.com/blog/2011/7/9/setting-up-an-microsoft-iscsi-target-and-initiator-using-mpi.html

    http://www.server-log.com/blog/2011/7/26/setting-up-an-microsoft-iscsi-target-and-initiator-using-mpi.html

    Anywhere that I can find this information from Microsoft?


    Microsoft Partner

    Wednesday, August 22, 2012 8:45 AM
  • So after my last post I did find some information from Microsoft that the ISCSI connections should be seperated by seperate subnets but it only states the fact and doesn't provide any detail:

    http://support.microsoft.com/kb/2535811

    What would be the optimal configuration from the two options below???

    ISCSI Target
    ISCSI-A-192.168.0.253 255.255.255.0
    ISCSI-B-192.168.0.252 255.255.255.0
    ISCSI-C-192.168.1.253 255.255.255.0
    ISCSI-D-192.168.1.252 255.255.255.0

    ISCSI Initiator
    HOST1-ISCSI-A-192.168.0.1 255.255.255.0
    HOST1-ISCSI-B-192.168.1.1 255.255.255.0

    HOST2-ISCSI-A-192.168.0.2 255.255.255.0
    HOST2-ISCSI-B-192.168.1.2 255.255.255.0

    OR:

    ISCSI Target
    ISCSI-A-192.168.1.1 255.255.255.0
    ISCSI-B-192.168.2.1 255.255.255.0
    ISCSI-C-192.168.3.1 255.255.255.0
    ISCSI-D-192.168.4.1 255.255.255.0

    ISCSI Initiator
    HOST1-ISCSI-A-192.168.1.2 255.255.255.0
    HOST1-ISCSI-B-192.168.2.2 255.255.255.0

    HOST2-ISCSI-A-192.168.3.2 255.255.255.0
    HOST2-ISCSI-B-192.168.4.2 255.255.255.0




    Microsoft Partner


    • Edited by rEMOTE_eVENT Wednesday, August 22, 2012 9:30 AM spelling
    Wednesday, August 22, 2012 9:29 AM
  • I don't understand why you are putting four NICs on the target, unless you want to isolate traffic from different hosts to different NICs.  I generally will use two subnets, iSCSI-A and iSCSI-B, on both targets and initiators and configure them with MPIO.  That takes care of failover and load-balancing.

    Your second example above appears to be trying to isolate traffic from the initiators, which is fine if you need to.  But unless you have security requirements to do that, I wouldn't do that until I had fully utilized the one pair of subnets. 

    I'm not sure if you could even get your first example configured.  I've tried thinking through it, and I can't see how it would work.


    tim

    Wednesday, August 22, 2012 1:47 PM
  • I am putting 4 NICs on the target for improved performance as 4 NICs is better than 2 surely?

    Target = 4 * 1gb

    Host1 Initiator = 2 * 1gb
    Host2 Initiator = 2 * 1gb 


    Microsoft Partner

    Wednesday, August 22, 2012 2:29 PM
  • Be careful if the iscsi client is hyper-v VM host. Windows server 2012 iSCSI target uses unbuffered I/O, means no read cache, no writeback cache.  If you use storage pool or regular HBA card/onboard SATA, the performance will be really bad when there are many VMs.  The solution is to either use a hardware RAID card with decent write-back cache, or use a iscsi target software implements software writeback cache, such as StarWind or 3rd party iscsi appliance solution like nexenta. I tried both and they worked great.

    Note: I don't work for either Microsoft or StarWind.

    Just my 2 cents. 

    Wednesday, August 22, 2012 9:33 PM
  • It depends on the switch infrastructure design between and the iSCSI Target(s).
    1) With the first configuration you can only have 4 paths:

    HOST1-ISCSI-A-192.168.0.1 255.255.255.0 can talk to
    ISCSI-B-192.168.0.252 255.255.255.0 and
    ISCSI-A-192.168.0.253 255.255.255.0            and

    HOST1-ISCSI-A-192.168.1.1 255.255.255.0 can talk to
    ISCSI-B-192.168.1.252 255.255.255.0 and
    ISCSI-A-192.168.1.253 255.255.255.0

    2) With the second config every of the 2 Host-NIC´s can talt to all 4 Target NIC´s (8 paths)
    3) Switching between the connections often takes time at the target
    4) The more LUN´s you have, the better many connections performing with MPIO

    Sunday, June 23, 2013 2:02 PM