Slow downloads using SFTP

Advertisement

aliengerm1
Joined:
Posts:
6

Slow downloads using SFTP

This is a repeat and summary of a related post.

Situation:
PC on one coast of USA
Unix (solaris) server on the other coast of the USA, running OpenSSH_5.6p1-hpn13v10
Ping: 80ms
Network connectivity: WAN network speed - 40mbps

Over long distance (WAN) on a tuned system, WinSCP 4.3.1 using SFTP (protocol ssh-2) caps around 690kbytes** on download and upload. Cipher AES or blowfish does not make a significant difference. (Ciphers make a large difference during local performance where CPU is more of an issue.)

We found that switching to Filezilla removed the download cap, reaching up to 4.4MB/s (40mbps - which was near the limit of the line). Upload was capped at 650kbytes, which has since been removed by the Filezilla devs (Fixed as of 3.3.5)

Speed difference:
Filezilla results: Transfer of 600mb file in 3minutes. 4.4MB/s

WinSCP 4.3.1 beta results: Transfer of the same 600mb file in 14minutes. 689KiB/s

Reply with quote

Advertisement

aliengerm1
Joined:
Posts:
6

I can only make an educated guess and say that I think the problem lies with a too small socket receive buffer.

More research:
I found another tool that has adjustable send/receive buffers. The default it negotiated was 1024kbytes, which was still slow. The ideal for this particular line seems to be 2048kbytes. My guess is that WinSCP has 512 send/receive buffers. Those should at minimum be upped to 1024 in general, and consider makeing that a user adjustable parameter since its useful particularly on large and long lines, aka WAN.

Reply with quote

aliengerm1
Joined:
Posts:
6

Thank YOU.

Update: I had a bit of software that had a default of 128kbytes, which autotuned to 1024kbytes for socket receive buffer. I then set default to 2048, then it autotuned to 4096. Autotuned = tcp sliding window adjustment, in the socket receive buffer. That's for download only, that particular bit of software performed poorly when it came to upload, so no good numbers.

I hate to put you on the spot but do you consider this a priority item or a low level item?

Thanks again.

Reply with quote

martin
Site Admin
martin avatar

aliengerm1 wrote:

I hate to put you on the spot but do you consider this a priority item or a low level item?
Rather of priority. Which means I'll take a look at it in a week or two.

Reply with quote

Advertisement

aliengerm1
Joined:
Posts:
6

winscp 4.3.2

I just tested the latest version, WinSCP 4.3.2.

(600mb test file)

California PC download from East Coast OpenSSH server using WinSCP 4.3.2 ~15minutes, high speed around KiB/s

California PC upload to East Coast OpenSSH using WinSCP 4.3.2 ~16minutes, high speed around 640 KiB/s


Sorry :(

Reply with quote

Advertisement

ErikSorensen
Guest

Re: winscp 4.3.2

Hi - came across this thread while googling this issue. Just to add my .02 -- I have 3.8.2 installed side by side with 4.3.2 on the same machine - 3.8.2 gets 4300 KB/s while 4.3.2 gets 30 B/s while trying to sftp upload to the same server.

Reply with quote

bmorgan
Guest

slow speeds with 4.3.2

i too am seeing very slow speeds when uploading files from my winxp pc to a redhat 5 linux machine (also slow to aix and solaris machines) (14mb in 24 minutes)

Reply with quote

martin
Site Admin
martin avatar
Joined:
Posts:
41,405
Location:
Prague, Czechia

Re: winscp 4.3.2

ErikSorensen wrote:

Hi - came across this thread while googling this issue. Just to add my .02 -- I have 3.8.2 installed side by side with 4.3.2 on the same machine - 3.8.2 gets 4300 KB/s while 4.3.2 gets 30 B/s while trying to sftp upload to the same server.
Can you try 4.2.9 for comparison?

Reply with quote

Advertisement

Guest

4.28 was now also slow... checked my speed setting on the NIC and it was set to "Auto" - changed this to 100 Full and am now working normally again (3mb sec)

Reply with quote

andilao
Joined:
Posts:
4

Today tested on a new Server 2008 R2, 2x Xeon E5620:
        DSL 10MBit/s   LAN 1GBits/s
WinSCP      208 KiB/s    2650 KiB/s
Tunnelier   210 kB/s     --
FileZilla   675 KB/s     13 MB/s !!

FTP over LAN 1GBits/s for comparison:
     
WinSCP      ~60 MB/s 
FileZilla   ~75 MB/s

Reply with quote

Tranton
Joined:
Posts:
2
Location:
USA

I get just the same problem when I try and login to my school's server to transfer something,
Error: ssh_init: Host does not exist
Error: Could not connect to server

Reply with quote

Advertisement

Guest

I did little test here:

Server: CentOS 5.6 x64 + SSH 5.8p1-hpn13v11 / vsftpd 2.0.5
Network: GigaLan
Client: Windows 7.1 x64 + WinSCP 5.0beta / FileZilla 3.5.1
File: 524 MB

WinSCP (SFTP-3 arcfour) download 22.5 MB/s
WinSCP (SCP arcfour) download 16 MB/s
WinSCP (FTP) download 105 MB/s

Reply with quote

Guest

Continue to the previous post.

WinScp (SFTP-3 AES-256) download 10.5 MB/s

FileZilla (SFTP AES-256) download 12.6 MB/s
FileZilla (FTP) download 105 MB/s

Tunnelier 4.4

Tunnelier (SFTP AES-256) download 15 MB/s
Tunnelier (SFTP arcfour) download 24 M/s

Reply with quote

Advertisement

You can post new topics in this forum