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I use a Cat-5e cable to transfer data to and from my samba share (using back to back connection). The maximum data transfer speed I am able to achieve is around 11 MBps.

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This image from How To Geek specifies the data transfer speed of Cat-5e cable to be 1Gbps i.e, 128MBps.

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I know that the data transfer speed is limited by the hard drive.I use an ATA hard disk ,which offer a data transfer rate over 30MBps , i guess.
lsscsi returns this :

[1:0:0:0] disk ATA Maxtor 2F040L0 VAM5 /dev/sda

But Why am I able to transfer data at only 11MBps ? What is it that I am missing ?Does it have anything to do with SMB share ?
Note: (around) 11MBps seems rather constant in most of the devices with a mechanical HDD ( atleast the ones I encountered).

Update :

Data transfer rate over http (seems little less though):

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Update 2:

Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10).

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  • Samba is a chatty protocol, with lots of back and forth messages, which limits data throughput. Did you try HTTP? Dec 19, 2013 at 17:50
  • no.but will give them a try.
    – Ashildr
    Dec 19, 2013 at 18:18
  • unless you have a bad cable or bad NIC/Switch port configuration, your issue is not network. are any of your disks connected by usb? you can tune your performance a bit based on this doc: samba.org/samba/docs/man/Samba-HOWTO-Collection/speed.html. I would set socket options = TCP_NODELAY, and mabey raw read=yes Dec 19, 2013 at 18:43
  • @allquixotic http offers less speed :see updated question.
    – Ashildr
    Dec 20, 2013 at 15:43

1 Answer 1

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This could be caused by one or more of a large number of factors including -

  1. Speed of the underlying disks. (I've seen disks that are not ancient only capable of putting out about 10 Megabytes per second). This would not surprise me on a 40 gig maxtor drive - and I think using a drive this old is probably foolhardy.

  2. Your network packets are inefficient - have you enabled jumbo frames ?

  3. Your Network cards might only be negotiating at 100 megabit and/or you might have duplexing issue.

  4. Your cable might be dodgy.

You may want to do some stress testing of each of the various subsystems, ie disk, network and CPU - using simpler tests and protocols to work out where things are going wrong. For example and HTTP request is a lot simpler then a SAMBA request, timing a "dd" of on your block devices might give you an indication of performance, doing a vmstat while transfer is running should show your utilization etc.

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    I don't think jumbo frames will help with Samba. At least until very recent versions of the Samba protocol, it was ridiculously chatty, so that the chattiness of the protocol effectively limited its transfer rate, even on very low latency connections. Fix might be to upgrade to a newer version of Windows for the samba server (or newer samba server if it's on Linux). Dec 19, 2013 at 18:02
  • +1 for the disks, a ATA disk is prolly only connected at 120, and is most likely the bottle neck
    – MDT Guy
    Dec 19, 2013 at 18:22
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    @allquixotic Version 2 (Vista/7) reduced chattiness by a fair bit, so it's actually vaguely usable over high latencies - I've been able to use it over 200ms links, though I have not benchmarked speeds. Version 3 (8/8.1) is apparently good enough to run a VM on a disk over SMB/CIFS... which is pretty crazy.
    – Bob
    Dec 21, 2013 at 14:13
  • turns out that my NIC only supports 10/100 Mbit/s.
    – Ashildr
    Dec 21, 2013 at 14:26

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