GB Network Performance TCP Tunning

Posted on 2011-05-01
Last Modified: 2012-05-11
HI Experts,

Been on this for a while need help can't understand why internel GB network speed are so slow i am only producing 35MB/s. I have played around with sysctl.conf but still can seem to get any higher speeds i was thinking of putting in extra nic cards and creating a bridge thinking maybe its the pci bus throughput i am still learning but i am like dog with bone won't give up can anyone point me in the right direction to achieve better speeds.

Cat 6 Cabling
PCI Reltek GB Nics (Supports Jumbo frame 7200 mtu)
Network Switch unmanged (Supports Jumbo Frame 9000 mtu)
OS = Debian, Ubuntu

Service over this network are for SMB,NFS,MYSQL,Bacula

Question by:Darrennew
    LVL 7

    Expert Comment

    At a guess...

    1) Check to make sure your disks or disk drive infrastructure is not the hold up
    2) you could try LAG (Ling Aggregation Group)  by connecting numerous NIC's and switches, even if you do it as a temporary measure. If it fixes the issue you know it was network related, if it does not fix the issue look at your I/O of your system/server
    LVL 1

    Author Comment

    Hi Thanks for you comment i just read up about LAG i don't i can this beacuse i have unmanged switch don't i have to bond ports on the switch as well?

    I forgot to mention i am using software raid 10 with 5 disk  array via linux kernel and using xfs file system.

    Can you suggest the best way to idientify if it is write performance on the raid array or file file system or network?

    LVL 9

    Accepted Solution

    I guess if the nic's are connected to the standard PCI bus, then PCI bus works with a maximum transfer rate of 133 MB/s, while Gigabit Ethernet runs up to 125 MB/s (1.000 Mbps / 8 = 125 MB/s). There are other factors like window size, synchronous or asynchronous and frame size. You can use something like NetCPS to check the throughput and the bottlenecks.


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