[nas-2000] Re: AW: Slow ftp bin transfer problem

  • From: "Alfred Bruckner" <alf_0001@xxxxxxxxxx>
  • To: <nas-2000@xxxxxxxxxxxxx>
  • Date: Thu, 27 Mar 2008 10:28:42 +0100

  there seems to be a solution for our problem!
Thank you Sven and stonki!!

You have to add in your proftpd.conf at /system/hddapp/etc/

UseSendfile off

Additional description can be found at:

Eventually you may add (although it is untested)

AllowStoreRestart on
AllowRetrieveRestart on

for latest tinky firmware the changes remain after reboot

for Raidsonic firmware changes are lost after reboot
you could edit and stop/start proftpd
/usr/hddapp/etc/rc.d/S91proftpd.sh stop
/usr/hddapp/etc/rc.d/S91proftpd.sh start


> -----Original Message-----
> From: nas-2000-bounce@xxxxxxxxxxxxx [mailto:nas-2000-bounce@xxxxxxxxxxxxx]
> On Behalf Of Tuchscheerer, Sven (K-EFFI/P)
> Sent: Wednesday, February 27, 2008 5:35 PM
> To: nas-2000@xxxxxxxxxxxxx
> Subject: [nas-2000] AW: Slow ftp bin transfer problem
> Hi Alfred,
> did someone forward the Problems written above to the proftpd "Engeneers"?
> As I know this pretty lightweight server is open source. Therefor I guess
> there´s @least a  moderate Group who can give some input to problem (not
> the solution - this might be like christmas ;-))
> greetz. Sven
> -----Ursprüngliche Nachricht-----
> Von: nas-2000-bounce@xxxxxxxxxxxxx [mailto:nas-2000-bounce@xxxxxxxxxxxxx]
> Im Auftrag von Alfred Bruckner
> Gesendet: Mittwoch, 27. Februar 2008 15:08
> An: nas-2000@xxxxxxxxxxxxx
> Betreff: [nas-2000] Slow ftp bin transfer problem
> Hello,
>   we are trying to find a solution for the "slow ftp bin transfer problem"
> There is also a German post at the nas2000 forum:
> http://nas2000.homeunix.com/thread.php?postid=464#post464
> Many users have the problem that ftp download through an internet
> connection
> from the NAS may be very slow.
> Test setup:
> PC - Internet - ADSL modem - Router - Switch - NAS
> Port forwarding (20,21) is configured for modem and router.
> I traced the packets sent/received from NAS (connected sniffer with HUB
> between Switch and NAS)
> What I know already:
> - ascii mode transfer is fast, bin mode may be slow
> - on local net ftp is fast
> - it is caused from too large packets sent from the nas
>   NAS always use packet size like if MTU=1500
>   e.g. NAS sends two large and one small packet - the two large ones are
>   rejected with "fragmentation needed" and the smaller one passes
>   --> retransmission...
> - MTU setting of ifconfig is ignored by ftp in bin mode
>   In ascii mode packet size is reduced accordingly
> - MSS setting of route command is ignored
> - MSS setting with SocketOptions in proftpd.conf is ignored
> - most PPPoE connections need a setting of MTU=1492 because of 8 bytes
>   overhead. That corresponds to MSS=1452.
> - same behaviour for Tinky and RS Firmware
> What I don't know:
> - how to tell proftp or the NAS to reduce the packet size as if MTU=1492
> Any ideas?
>   HWguru (Alfred)

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