VM hiccups during file copy in Windows 2012 and SMB 3.0

    General discussion

  • Hello!

    I have built the cluster with 4 Hyper-V cluster hosts and a storage over SMB 3.0. Everything is working fine on the hosts and storage when I copy a file of 4GB+. The problem appears when I copy the file to one of the VMs that is hosted on the storage.

    Here is what I get:

    The speed in this case falls to 15MBps. In the beginning it was looking good for about 10 seconds. The speed was averaging to 90MBps. I am copying the file from another physical workstation outside of the cluster but connected to the same physical switch.

    Any idea on why it can happened? Have I created the SMB Share wrong? Configurations? The same host can accept the same file with the full 1Gbps speed.

    Thank you!

    Wednesday, July 03, 2013 2:45 PM

All replies

  • Are the SMB drives the drives for the storage of the VMs or are they general purpose file shares?  Does your VM reside on a dynamic disk versus a fixed disk?

    .:|:.:|:. tim

    Wednesday, July 03, 2013 7:29 PM
  • What hardware is backing the SMB server?  This looks like a pattern we might see if the storage supports ODX (offloaded data transfer).

    -Taylor Brown
    -Program Manager, Hyper-V

    Wednesday, July 03, 2013 8:05 PM
  • Hello Tim!

    The SMB 3.0 is for Applications, so VHDs are there. I am using Fixed disk to increase the performance.

    Thank you!

    Thursday, July 04, 2013 8:32 PM
  • Hello Taylor Brown!

    I am using SuperMicro motherboard with 2 quad core Xeons. The CPUs are L5420. There are 24GB of RAM. The controller is LSI 9207-8i. There are 8 HDDs connected to the controller. All are the same and it is Black series of WD 2TB each. I do not remember the model but it is 7200rpm.

    Can you give me a little more info on ODX? How to check it? It happened only on VM, if I use cluster host to copy the file - everything is fine!

    Thank you!

    Thursday, July 04, 2013 8:39 PM
  • The HDDs are WD2002FAEX. 8 of them in RAID 10.

    Thank you!

    Friday, July 05, 2013 1:12 PM
  • Still trying to get a handle on the configuration based on your description.

    4 nodes in a cluster.  Each node has an LSI SAS controller.  These controllers are connected to some sort of storage shelf (assumed) that contains 8 disk drives.  Where does the SMB 3.0 come into play?  Generally when you talk about SMB 3.0 for storing VHD files for a Hyper-V cluster, the SMB 3.0 file server is another cluster or a storage array that can be configured with SMB 3.0.  You cannot have the SMB storage configured on the cluster and use it 'locally'.

    ODX is a feature of storage arrays.  When a request is made to copy data from one location to another location on the storage array, the storage controllers take care of moving the data without the involvement of the Windows hosts.  Significant performance improvements.  From the description of your environment, it does not sound like you have a storage array.

    .:|:.:|:. tim

    Friday, July 05, 2013 3:40 PM
  • Hello Tim!

    Here is approximately what I have. when you se 4 Gbps it means I have 4 x 1Gbps wires connected to the switch.

    Physical switch 0 is for LAN and Management. The Physical Switch 1 is for Storage, Cluster, Live Migration traffic. SAN has a motherboard and LSI adapter with 8 HDDs (not a highly available).

    Let me know if you have more questions.

    Thank you!


    • Edited by Compell Friday, July 05, 2013 3:56 PM remove some extra junk...
    Friday, July 05, 2013 3:55 PM
  • by the way, I am using Cisco SRW2048 for both physical switches.
    Friday, July 05, 2013 3:59 PM
  • Hello Tim and Taylor!

    I am just wonder if you can direct me to the solution for this issue. It still there and I am not aware on what to look for. I have tried to find info on ODX but it did not bring me to the solution.

    Thank you!

    Tuesday, July 09, 2013 1:36 PM
  • SMB 3.0 for application is not meant for copying files like general purpose file shares.

    It is meant for VHD & VHDX files

    It does not have any cache.  That's why you're getting the hiccups

    Wednesday, February 05, 2014 11:27 PM