Date: Wed, 21 Nov 2012 09:43:36 -0800 From: Mehmet Erol Sanliturk <m.e.sanliturk@gmail.com> To: Kevin Oberman <kob6558@gmail.com> Cc: freebsd-net@freebsd.org, Benjamin Villain <benjamin.villain@ucopia.fr>, Marc Peters <marc@mpeters.org> Subject: Re: Low Bandwidth on intercontinental connections Message-ID: <CAOgwaMubZuXukAeEuCCyViM6MRqW2Ko8vR4ZanjepJz7AuDrcQ@mail.gmail.com> In-Reply-To: <CAN6yY1tZ=K32gRzV1DER82ksZJ6sJ-45DZAfZTX3uBvh1gvUzQ@mail.gmail.com> References: <50ACF62C.8000408@mpeters.org> <CAOgwaMuUuJ2%2BmKqsFVp=DyVFkfm8Et%2Brnt2iEGDO8i1Kt_kDVA@mail.gmail.com> <50ad087d.1892cc0a.2cce.3bf2@mx.google.com> <CAN6yY1tZ=K32gRzV1DER82ksZJ6sJ-45DZAfZTX3uBvh1gvUzQ@mail.gmail.com>
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On Wed, Nov 21, 2012 at 9:20 AM, Kevin Oberman <kob6558@gmail.com> wrote: > On Wed, Nov 21, 2012 at 8:58 AM, Benjamin Villain > <benjamin.villain@ucopia.fr> wrote: > > I don't think this is about disk or memory leak as transfering files > locally > > seem to work fine. > > > > Can you test transferring files from (and to) your Linux boxes to (and > from) > > the FreeBSD servers to check that it is not a network issue inside your > DCs. > > > > King regards, > > > > -- > > Ben > > > > > > Mehmet Erol Sanliturk writes: > > > >> 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 . > > If you have not done so, I suggest you use SIFTR to capture data on > what is happening in TCP. It can often tell you a great deal and is > very easy to work with. Just load the kernel module and use sysctls to > control it. I have used it in conjunction with tcpdump and wireshark > to find performance problems. > > Also, for high performance on bulk data transfers over long, fat > pipes, take a look at http://fasterdata.es.net. It is a detailed guide > on moving data developed by the people who have to deal with the huge > volumes of Large Hadron Collider data moving across the Atlantic from > CERN to researchers in the US. (Note that this is not FreeBSD > specific.) > -- > R. Kevin Oberman, Network Engineer > E-mail: kob6558@gmail.com > A very good link . In the above site , please see the following especially : http://fasterdata.es.net/data-transfer-tools/say-no-to-scp/ Say No to scp Why you should avoid scp over a WAN and http://fasterdata.es.net/data-transfer-tools/scp-and-sftp/ scp and sftp Thank you very much . Mehmet Erol Sanliturk
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