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Thread: Cannot sustain network speeds

  1. #1
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    Default Cannot sustain network speeds

    Hi all,

    I just noticed something.

    When I transfer a large file, like an opensuse iso image from the server to the desktop or vice versa, the speed start pretty good (about 40MB/s) it stays there for about 30 seconds, then drops off to about 6MB/s.

    The Windows XP machine in the same network doesn't do this with the same file.

    All machines, including server tower, have the Intel Pro GT1000 network card, and all the network is Cat5e/6 and gigabit switches.

    Wondering why the Opensuse machines are doing this, and can it be fixed.


    Thanks

    Heeter
    Linux Counter 475994

  2. #2
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    Default Re: Cannot sustain network speeds

    The transfer rate ability of your cables etc is probably much faster than the ability of your HD's, the speed at which they can I/O is what matters.

    Does windows actually transfer the file more quickly? Have you timed it?
    Tumbleweed_KDE
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  3. #3
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    Default Re: Cannot sustain network speeds

    Try adding this line to the [global] paragraph in your smb.conf file:
    socket options = TCP_NODELAY SO_SNDBUF=8192 SO_RCVBUF=8192
    Probably good idea to use copy/paste

    However that was a long, long time ago that that was in vogue. Probably Samba adjusts automatically by now -- so if it doesn't help, remove it.
    Leap 42.3 & 15.1 &KDE
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  4. #4
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    Default Re: Cannot sustain network speeds

    When you transfer the first few blocks of the file, the recipient hasn't written them to disk yet. Eventually it has to write something to disk and then if blocks are coming in faster than disk writes can be done on average, the rate will be throttled back. Something similar applies for the sending side.

    In addition, initially the number of blocks and the elapsed times are small, thus giving very rough and inaccurate instantaneous speeds when divided. It's the settled state rate of transfer that is a better indicator of the real speed.

  5. #5
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    Default Re: Cannot sustain network speeds

    Quote Originally Posted by caf4926 View Post
    The transfer rate ability of your cables etc is probably much faster than the ability of your HD's, the speed at which they can I/O is what matters.

    Does windows actually transfer the file more quickly? Have you timed it?
    Hi Caf,

    Yes I have tested and timed. Average sustained speed of WindowsXP machine moving an opensuse64bit iso image to the server and back is around 44MB/s. The two Opensuses (one 64bit) are both at 8MB/s. This is calculating 4.3G divided by how much time it takes.

    Heeter
    Linux Counter 475994

  6. #6
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    Default Re: Cannot sustain network speeds

    Then there is something wrong because 44MB/s is more like what a gigabit link should sustain, and 8MB feels more like a 100Mb/s link.

  7. #7
    ab@novell.com NNTP User

    Default Re: Cannot sustain network speeds

    -----BEGIN PGP SIGNED MESSAGE-----
    Hash: SHA1

    Take the hard drive out of the equation:

    http://www.novell.com/coolsolutions/tools/19485.html

    Still, I agree. The link may not be realized if the NICs are not
    setting the proper mode (100 vs. 1000 Mbit).

    Good luck.

    ken yap wrote:
    | Then there is something wrong because 44MB/s is more like what a gigabit
    | link should sustain, and 8MB feels more like a 100Mb/s link.
    |
    |
    -----BEGIN PGP SIGNATURE-----
    Version: GnuPG v1.4.2 (GNU/Linux)
    Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

    iD8DBQFIg2s43s42bA80+9kRAji4AJ9kqwsToVvaLOww9oHl780QHfVG3gCcDeQq
    X7K1FKzT/gLV0VeXgSZprY4=
    =xBX9
    -----END PGP SIGNATURE-----

  8. #8
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    Default Re: Cannot sustain network speeds

    Hi Guys,

    Thanks for the help so far.

    I did what swerdna asked me to put into my smb.conf, and it knocked out my mouse and keyboard.

    I cannot get around my machine.

    I finally got another keyboard up and running, I managed to go back to my smb.conf to remove that line, and it is not there, yet nothing works.

    Please help!!

    I would like to fix this first before continuing with the network issue


    Thanks

    Heeter
    Linux Counter 475994

  9. #9
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    Default Re: Cannot sustain network speeds

    Heeter wrote:
    > I did what swerdna asked me to put into my smb.conf, and it knocked out
    > my mouse and keyboard.


    When I saw your original post, I didn't believe that smb.conf could affect a
    mouse and keyboard. Please open a terminal and enter the command

    dmesg | less

    This will bring up the log file for the current boot and page it for you. You
    can move up/down in the file with pg up/down, the up/down arrow keys or get a
    new page with the space bar. When you are done looking, type a q to quilt. Look
    over the output for anything related to your non-functioning keyboard or mouse.
    You can post any sections that look suspicious. The system is pretty chatty, so
    we usually do not want everyting posted.

    Larry

  10. #10
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    Default Re: Cannot sustain network speeds

    When you transfer the first few blocks of the file, the recipient hasn't written them to disk yet. Eventually it has to write something to disk and then if blocks are coming in faster than disk writes can be done on average, the rate will be throttled back. Something similar applies for the sending side.

    In addition, initially the number of blocks and the elapsed times are small, thus giving very rough and inaccurate instantaneous speeds when divided. It's the settled state rate of transfer that is a better indicator of the real speed.
    This is really what I was saying earlier too. Not really my field, but surely it like the water out of a pipe story - it doesn't matter how much you push thru one end - you can only get out as much as the narrowest point will allow.

    So you are saying - if you put a stop watch to it (not going of what it's telling you) - the windows machine shifts it THAT much quicker!
    If so, then there does seem to be a problem. But as I say, not my field really.
    Hope you get it sorted Heeter
    Tumbleweed_KDE
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