Win2008R2 + 10Gbps network = slow file copy and SQL performance


  • Hi,

    I try to understand why my 10Gbps network cant copy more than 50MBps.

    using a file copy, xcopy or robocopy, I got 50MBps even if I try to copy multiple files in parrallel.

    I also have SQL Server and here too the performance dont go higher than 50MBps

    my disks are able to handle 800MBps

    when I do a PSPing test, I'm able to get 25% of the bandwdth up to 60% when I execute 4 PSPing tests at the same time.

    So between 5% and 25% its 5 times slower, compared to the 60% 12 times slower...

    I play with the netsh autotuning option, offloading etc... the intpolicy tool but still same result.

    Generally I'm able to reached 80% of the bandwidth the first time I connect my network, everything else just add few % and fine tune the connectivity, but here... 5% and 60% max when I stress a lot, I never see this before.

    what's information I should check at the switch level to validate this side of the traffic?

    My server has 256GB of RAM and 2 CPU 8 Core each (16 thread) for a total of 32, is there something special to do when there is a lot of CPU and RAM?

    Friday, October 04, 2013 9:24 PM


All replies

  • Hi,

    can you try to exchange data with Windows 2003, 2000 or xp... if it is working try to disable smb 2.0 (you will have to reboot the server, to apply):

     Add a new REG_DWORD key with the name of Smb2.
     Value name     Smb2
     Value type     REG_DWORD
     0 =     disabled
     1 =     enabled
    0 to disable SMB2
    1 to re-enable SMB2

    You can read that too:

    the MTU Size can be a problem too.

    But in most case the network throttling mechanism of SMB 2.0 is causing this problem.

    Saturday, October 05, 2013 8:37 AM
  • thanks

    I'll try disabling the smb2, only windows 2008R2 and R1 servers communicates to each other, no workstation.

    but not sure if this will help the SQL Server traffic, there is no SMB involved.

    I'm waiting for the feedback of the network guy to know the MTU size configured at the switch level (I would like to use jumbo frames)

    Saturday, October 05, 2013 12:16 PM
  • Yes it will help with smb exchange over networks shares: like file copy.
    Is your probleme about pur SQL performances?
    If it is, how is your local/remote queries, are you using remote storage (iscsi, FC), different disks for: tempdb transac log sql data. Have you tried to benchmark with SQLIO?

    How is your SQL topology (including the SQL version) and at which level is the bottleneck?

    Sunday, October 06, 2013 9:49 AM
  • disabling smb2 didn't changes the performance, maybe a improvement of small improvement.

    the disks are able to deliver 800MB/sec, benchmarked with SQLIO. (its a FCoE SAN connection with 8 LUNs, I don't know how its setup, I don't choose the hardware and the config)

    there 32 cpu/core/thread and 256GB of ram, my tests are made using a 50GB table which fit in the memory.

    currently doing a simple test like select * from testable results in 30MB/sec of throughput most of the time. sometimes its lower sometimes a little faster.

    reading in parallel results in a max of 60MB/sec when I'm lucky. (in both read and write accesses, no matter the direction of the test) , while I expect a more linear growth

    and the wait stats are the network in SQL Server.

    Sunday, October 06, 2013 1:30 PM
  • ok, I've no knowledge with FCOE, the only thing I can say is to verify the MTU value (must be around 2500 with FCOE), you can have a look on the cluster size of the partition 64k is the common value for sql.

    On thing more, you will never have the max speed related by the vendor for the hard-drive, it mainly depends of the block size "you" are using.

    Sunday, October 06, 2013 6:21 PM
  • my problem is not at the disk level.

    its at the network level.

    Sunday, October 06, 2013 7:56 PM
  • Hi,

    Firstly, please refer to the similar thread below:

    what causes windows 2008 r2 slow file & folder copy?

    Maybe this issue is because the TCP transmission does not recover immediately after a retransmit occurs or the TCP component cannot expand the TCP receive window. In this situation, the total network bandwidth cannot be used.

    Slow data transfer speed in Windows 7 or in Windows Server 2008 R2

    In addition, the link below maybe helpful to you:

    Slow file copy or slow file transfer with various Windows versions 2k8, 2k8R2, 2k3

    Note: Microsoft is providing this information as a convenience to you. Please make sure that you completely understand the risk before retrieving any suggestions from the above link.

    Best regards,


    Monday, October 07, 2013 9:42 AM