topic Re: FTP SCRIPT in Operating System - HP-UX

FTP SCRIPT

Ash_4 — Tue, 27 Aug 2002 12:10:43 GMT

Hi Masters,
I have seen one ftp software "Download Accelerator" (Windows xx ), which is spliting the file in multiple segment and receving /transmiting the segment simulteneously. After receiving the segments it combines the segment in one to get the file.
Is it possible to do the same in unix.

Thanks.

Re: FTP SCRIPT

H.Merijn Brand (procura — Tue, 27 Aug 2002 12:16:15 GMT

look at 'wget'

ftp://download.xs4all.nl/pub/mirror/gnu/wget/
http://hpux.cs.utah.edu/hppd/hpux/Gnu/wget-1.8.1/

Re: FTP SCRIPT

Shannon Petry — Tue, 27 Aug 2002 13:51:22 GMT

Some food for thought. How can cutting a file into segments accelerate file transfer? You'd have to add header/tail info and encapsulate each segment so you knew how it was to be re-assembled, so how can you make that any smaller?
Also, if you had a client that did this, the server would have to support it... none that I know of do, but all my servers do support reget.

So, just wondering how it would be of any benefit accept that you could download lets say 14 of 15 pieces, then later get the 15th? And if this is the case most current ftp daemons support reget functions so you dont have to do this..

Regards,
Shannon

Re: FTP SCRIPT

Erik Tong — Wed, 28 Aug 2002 15:38:23 GMT

Spliting the file and sending in multiple ftp sessions can accelerate the transfer by fully utilizing the network connection. Usually just one ftp transfer cannot.

The server does not have to support anything really special. It just has to have to be able to download a part of a file starting at a particular byte offset. FTP servers that can resume an interupted download can do this.

After the client has completed several downloads it just concatenates them together into the original file.

Re: FTP SCRIPT

Wodisch_1 — Wed, 28 Aug 2002 16:30:13 GMT

Hi Ash,

have a look at "rsync" as it can transmit only the "deltas" of remote files (compared to locla ones) and it can use SSH for the transport, thatway not showing your password!

http://rsync.samba.org

HTH,
Wodisch

Re: FTP SCRIPT

Volker Borowski — Wed, 28 Aug 2002 16:48:14 GMT

Hi,

I think the reasons for these "tools" is to encounter the capability of some routers to detect FTP traffic and reduce bandwidth for this traffic.

The main reason for this router behavior is to keep networks working. If you have low-speed lines between two spots, a big FTP can bring down all other activities. So some routers can be configured to delay ftp-packets, to keep the rest of the network alive.

I doubt (following Shannon) that these "tools" will have a big benefit in LAN environments and I think you will create new problems in WAN and Internet environments.

Just my 0.02???
Volker