Date: Wed, 21 Nov 2012 08:47:23 -0800 From: Mehmet Erol Sanliturk <m.e.sanliturk@gmail.com> To: Marc Peters <marc@mpeters.org> Cc: freebsd-net@freebsd.org Subject: Re: Low Bandwidth on intercontinental connections Message-ID: <CAOgwaMuUuJ2%2BmKqsFVp=DyVFkfm8Et%2Brnt2iEGDO8i1Kt_kDVA@mail.gmail.com> In-Reply-To: <50ACF62C.8000408@mpeters.org> References: <50ACF62C.8000408@mpeters.org>
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On Wed, Nov 21, 2012 at 7:41 AM, Marc Peters <marc@mpeters.org> wrote: > Hi list, > > we are experiencing low throughput on interncontinental connections with > our FreeBSD Servers. We made several tests and are wondering, why this > would be. The first tests were on an IPSEC VPN between our datacenter in > DE and Santa Clara, CA. We are connected with two gigabit uplinks in > each DC. Pushing data by scp between our FreeBSD servers takes ages. > Starting with several MB/s it drops to 60-70KB/s: > ..... I do not have any answer to your question , but I want to share one my experiences . I Linux ( KDE ) I was copying a hard disk contents to another drive by using Dolphin . At the beginning it was very fast , but over time its speed reduced to a few kilobytes per second . It listed completion time left as months . I inspected why this is the case . The reason was the following : On each file it is copied , the Dolphin was producing approximately 1 Kilobyte memory leak . After copying more than one million file , all of the memory exhausted and it started to swap memory to hard disk swap space which reduced copy speed to a few kilobytes per second . I stopped the Dolphin and copied small directory groups by restarting the Dolphin . This cured the problem because on each exit , all of the leaked memory by Dolphin has been disposed ( where "Undo" item of Dolphin menu was disabled means memory is not reserved for undo ). Please study your data transfer software for such a possibility . It may not be problematic in Linux but FreeBSD version may have some trouble points . There is another possibility : Graceful degradation . http://en.wikipedia.org/wiki/Graceful_degradation http://en.wikipedia.org/wiki/Fail_soft A program part may produce graceful degradation over time or processed data : For example , assume a list is searched by sequentially . When list length grows , search times also grows linearly and produces a degradation although there is no any error in the process . You may study your system with respect to such a process . These are the possibilities which come to my mind . Thank you very much . Mehmet Erol Sanliturk
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