Re: Why is WinSCP so slow?
I read the manual....still downloads slow
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I also noticed that 5.0.7 is much slower, with blowfish I can achieve only around 4MB/s max, with AES I'm getting 10MB/s on 100Mbit network, but cpu usage is very high. Is winscp using AES-NI instruction set on cpus which support them?
winscp version:5.15.1 Portable
OS version: win10 1809
linux server version: centos 7.6 mini
winscp options:
close compression
algorithms is DES
WinSCP speed is 400KB/s~500KB/s
Pscp speed is 60/s-70MB/s
I don't get the point. See, directory reading is really slow in long-distance link. Why should NOT we use multithreaded connection (also with connection reuse!!!)? I bet all modern browsers use this technique to increase performance -- even save ROUND TRIP TIME! Is multithreading hard? Does it use too much resources? All I know is that if not multithreaded the directory reading takes forever to complete. Plus the file search is also very slow -- sequence searching? one by one? this is inefficient. There's no way to tune the SSH proto itself actually -- I tried disabling compression but it doesn't seem to work at ALL.
I would to know on my personal laptop the file transfer is very slow but on my office the transfer rate is very high. I don't know how to fix this problem. I have copy the same setting from my lab but still on my personal laptop it is slow.
There are many potential causes, but in my experience, the stock SCP/SFTP protocols do not scale up in bandwidth very well in the face of any latency in your connection. There are patches to OpenSSH (probably the most commonly used SSH/SFTP server on the Internet) that address all of these protocol-induced performance problems, but the upstream will never accept them into the mainline codebase. Some distros have adopted the patches, like Gentoo.I'm only getting a transfer rate of 1500KB/s from my Linux server to my Windows computer. The windows computer is running Linux and Windows as dual boot, when I scp from Linux to Linux I get ~8MB/s transfer rate without compression enabled.
I checked WinSCP options and compression is off, I just downloaded the latest version 4.0.5 and it is the same problem.
I need to transfer 25GB from Linux to Windows and WinSCP estimates 4.3 hours, I can burn the files to DVD faster then that....
Any ideas on what is causing this?
:evil:
We have either 4 Gb/s or 20 Gb/s availability to transfer to theo hosts based on ethernet networks from differing sources.
Back end is SSD Raid 10 on 16 Gb/s Fibre or 20 Gb/s iSCSI (Separate bandwidth from the ethernet) depending on which store used. Performance is the same both
I can can open 10 transfers from the same host through winSCP to ESX, and several more from other hosts, or just one from one host, and they'll be 10,000 KiB/s each.
No matter what I do, each thread of the transfer is limited to just over 10,000 KiB/s
I am using SCP, and I've tried playing with the settings according to the FAQ, and all I can do is reduce the speed by changing to Blowfish over AES 256 (counterintuitive) and optimizing bandwidth reduces me to the same amount as changing the encryption (about 7,000 KiB/s)
I also tried to out FTP server using SFTP and still 10,000 KiB/s while other transfers don't get this limit.
Fixed a couple things typos ad grammar just a bit from above.
Note, i upgraded my WinSCP from 5.5.5 and now I'm getting a slightly better max-out of speed at about 100 Mbit/s (12.6 MB/s Max reported by the UI) on SCP (I DID have to disable the optimize feature now though, as it would bring me down to about 360 KB/s when enabled.)
on SFTP I'm also hitting the same max speed, so I'm guessing something in the putty code is the limitation now..
Also, I tested SFTP and it was slightly faster than SCP before upgrade no matter how I changed the settings.
I have another environment with the same 5.5.5 code and I'm seeing wildly different values for SCP (1,800 KiB/s max) verses SFTP (11,500 KiB/s Max) Even after changing around the settings several times.
I'll try upgrading that one too, and see if I can at least get it to be 100 Mb/s per stream the way the DR site is for both FTP and SCP now. (Upgraded to 5.10.1 (Build 7725) By the way)
:evil:
We have either 4 Gb/s or 20 Gb/s availability to transfer to theo hosts based on ethernet networks from differing sources.
Back end is SSD Raid 10 on 16 Gb/s Fibre or 20 Gb/s iSCSI (Separate bandwidth from the ethernet) depending on which store used. Performance is the same both
I can can open 10 transfers from the same host through winSCP to ESX, and several more from other hosts, or just one from one host, and they'll be 10,000 KiB/s each.
No matter what I do, each thread of the transfer is limited to just over 10,000 KiB/s
I am using SCP, and I've tried playing with the settings according to the FAQ, and all I can do is reduce the speed by changing to Blowfish over AES 256 (counterintuitive) and optimizing bandwidth reduces me to the same amount as changing the encryption (about 7,000 KiB/s)
I also tried to out FTP server using SFTP and still 10,000 KiB/s while other transfers don't get this limit.
Fixed a couple things typos ad grammar just a bit from above.
:evil:
We have either 4 Gb/s or 20 Gb/s availability to transfer to theo hosts based on ethernet networks from differing sources.
Back end is SSD Raid 10 on 16 Gb/s Fibre or 20 Gb/s iSCSI (Separate bandwidth from the ethernet) depending on which store used. Performance is the same both
I can can open 10 transfers from the same host through winSCP to ESX, and several more from other hosts, or just one from one host, and they'll be 10,000 KiB/s each.
No matter what I do, each thread of the transfer is limited to just over 10,000 KiB/s
I am using SCP, and I've tried playing with the settings according to the FAQ, and all I can do is reduce the speed by changing to Blowfish over AES 256 (counterintuitive) and optimizing bandwidth reduces me to the same amount as changing the encryption (about 7,000 KiB/s)
I also tried to out FTP server using SFTP and still 10,000 KiB/s while other transfers don't get this limit.
Lastest version here, using pscp.exe I get an average of 40MB/s, using WinSCP it starts at 40MB/s and rapidly drops to ~600KB/s.
I'm using SCP protocol, is there some setting that I'm missing?
What speed do you get with SFTP protocol?
Lastest version here, using pscp.exe I get an average of 40MB/s, using WinSCP it starts at 40MB/s and rapidly drops to ~600KB/s.
I'm using SCP protocol, is there some setting that I'm missing?
Thanks for the suggestion. I've installed 5.8 beta and the transfer speeds are better. The burst is up to my bandwidth max (around 5 MB/s), but for large files it settles in around 1 MB/s. This may be a limitation of the server I'm downloading from however, since I'm observing the same behavior while using Filezilla as well. Good job on on the performance improvements!
I'm experiencing the same download speeds with a similar hardware setup and also using version 5.7.6. I've also tried the different combinations of SCP and SFTP recommended in the FAQ. My observations are that SFTP gives a consistent 700 KB/s to 800 KB/s transfer speeds whereas SCP will initially max out my bandwidth at 4 MB/s but then drop drastically to around 200 KB/s before settling down around 600 KB/s which is still slower than SFTP.
I've also just tried setting the priority up to HIGH in windows for WinSCP but that doesn't seem to have any noticeable effect. I will try out Filezilla and compare the two speeds.
Thanks for your report.
Can you try 5.8 beta?
It has some performance improvements, particularly for SFTP.
I'm experiencing the same download speeds with a similar hardware setup and also using version 5.7.6. I've also tried the different combinations of SCP and SFTP recommended in the FAQ. My observations are that SFTP gives a consistent 700 KB/s to 800 KB/s transfer speeds whereas SCP will initially max out my bandwidth at 4 MB/s but then drop drastically to around 200 KB/s before settling down around 600 KB/s which is still slower than SFTP.
I've also just tried setting the priority up to HIGH in windows for WinSCP but that doesn't seem to have any noticeable effect. I will try out Filezilla and compare the two speeds.
This is totally wrong for my situation... My i7-4790 is only at 3% Usage for all processes at the writing of this and my transfer speed is only ~500KB/s. I was getting 16MB/s with Filezilla. It is not my CPU, that is for sure. What is it that it limiting me, I do not know. I will only know when the problem is solved.
Thanks for your report.
Can you send me an email, so I can send you back a development version of WinSCP for testing? Please include link back to this topic in your email. Also note in this topic that you have sent the email. Thanks.
You will find my address (if you log in) in my forum profile.
I was facing a similar situation: version 5.7.6 , low CPU usage (4%) and low speed (400 KB/sec). I solved reverting to Normal debug level (I needed to raise it in the past) and the transfer speed is about 10MB/sec downloading from a remote site.
Hope this helps someone.
Thanks to Martin for the great software.
This is totally wrong for my situation... My i7-4790 is only at 3% Usage for all processes at the writing of this and my transfer speed is only ~500KB/s. I was getting 16MB/s with Filezilla. It is not my CPU, that is for sure. What is it that it limiting me, I do not know. I will only know when the problem is solved.
Thanks for your report.
Can you send me an email, so I can send you back a development version of WinSCP for testing? Please include link back to this topic in your email. Also note in this topic that you have sent the email. Thanks.
You will find my address (if you log in) in my forum profile.
This is totally wrong for my situation... My i7-4790 is only at 3% Usage for all processes at the writing of this and my transfer speed is only ~500KB/s. I was getting 16MB/s with Filezilla. It is not my CPU, that is for sure. What is it that it limiting me, I do not know. I will only know when the problem is solved.
Registered to say most of the stuff in the thread is incorrect, WinSCP has had a cap of sshd file transfers (SFTP) because of the sshd crypto being a single process and maxing out a cpu core for transfer speeds on 1gbps connections, for example one of my 32core servers will encounter max speeds of around 13KiB/s (according to WinSCP) on any single threaded transfer process that is encrypted for the most part..
known fixes are:
https://www.psc.edu/hpn-ssh-home/hpn-ssh-faq/
you'll find HPN as well as what I've said all over the internet for SCP or SFTP, either or doesn't matter or make a difference. SFTP is an upgraded version of SCP.
I've used winscp back quite a few years, if I'm actually on a windows client it's my go to.
having network speed and hard drive speed many times over the "limit" you'll see your CPU max out before anything else does, using HPN you'll see speeds go up without changing winscp
tl;dr your server cpu single threads limit your transfer speed, it isn't winSCP.
First of all, thank you for creating such a well designed program. However, i too think there is some kind of performance issue. This becomes obvious if i try to download a folder with a great number of small files. In Filezilla i can set up up to 10 simultaneous connections and download starts immediately. In WinSCP it seems as if the contents of the folder are scanned first, and the program then starts to download one file after another (at least this is what the status window led me to believe), although it already knows the contents of the folder. Is this just my impression or is that really what happens? Maybe that is the cause of the sluggish performance?
I am in the same position with Sardjent, i tried to use WinSCP as a filezilla replacement but it looks like there is a huge performance difference between the two.
Just wanted to chime in with my experiences. I'm looking for a replacement for filezilla as it is now bundled with adware so WinSCP would seem like a good fit for me, however, I'm getting disappointing metrics when doing a file transfer.
My test task was to upload a Windows Azure hosted web site over regular ftp with ~1000 files at ~100Mb, lots and lots of directories.
FileZilla 3.7.3, 10 threads needs 40 seconds to get this done.
WinSCP 5.5.1, 9 threads, Unlimited speed needs almost 7 minutes.
When I noticed how slow WinSCP was going, I fired up FileZilla and started the exact same file transfer simultaniously to another directory and it finished way before WinSCP did.
This is on Win 7, latest patches, no proxy but probably some Microsoft ISA Server on my gateway to the internet doing funny business transparently with http and ftp connections (I know this because this server has interfered with filezilla before, it doesn't anymore though).
I also noticed that 5.0.7 is much slower, with blowfish I can achieve only around 4MB/s max, with AES I'm getting 10MB/s on 100Mbit network, but cpu usage is very high. Is winscp using AES-NI instruction set on cpus which support them?
I must admit 5.0.5 was fastest version I ever used. 5.0.6 is slower and 5.0.7 is as slow as 4.x for me. Working on 100Mbit LAN, in SCP mode with Blowfish encryption I am getting <500kb/s :( 5.0.5 was 2-3 times faster.
Lastly.. why was the increased buffer size pulled from the 4.3 branch?
I am leaning towards using the 5.x beta version within production, but the retraction of the buffer code has me a bit worried.
"reasonably stable" enough to introduce into a production environment?
I use WinSCP(sftp) as the transport agent within my file ingest framework. Would you consider 5.0.5-beta production ready? Stable enough?
It is reasonably stable. Though not as stable as 4.3.x yet.
I use WinSCP(sftp) as the transport agent within my file ingest framework. Would you consider 5.0.5-beta production ready? Stable enough?
It is reasonably stable. Though not as stable as 4.3.x yet.
I use WinSCP(sftp) as the transport agent within my file ingest framework. Would you consider 5.0.5-beta production ready? Stable enough?
I can confirm that 5.0.5 build 1782 has solved my speed issues as well (and quite nicely, at that). My SFTP uploads have traditionally struggled to hit 400 Kbps on a very large pipe, and now they easily reach 9 Mbps. Thanks so much!
Thanks a lot for feedback!
I can confirm that 5.0.5 build 1782 has solved my speed issues as well (and quite nicely, at that). My SFTP uploads have traditionally struggled to hit 400 Kbps on a very large pipe, and now they easily reach 9 Mbps. Thanks so much!
Currently using 5.0.5 Build 1782 and not having speed issues... <<snip>>
Currently using 5.0.5 Build 1782 and not having speed issues, able to upload at my connection's max rate (~500 KB/s). However 4.3.5 and 4.3.6 were being mysteriously being capped at about 50 KB/s for some reason; I had all limiters that I could find disabled.
Can I ask all people posting here to mention version of WinSCP they are using? Thanks.
Can I ask all people posting here to mention version of WinSCP they are using? Thanks.
don't forget to check if your firewall cause the slow speed. i also had speed problems and partly my firewall cause the loss of speed.
How do I check for this? And if found, how do I correct this?
don't forget to check if your firewall cause the slow speed. i also had speed problems and partly my firewall cause the loss of speed.
Hi,
has anything happend regarding speed lately? I just installed the latest version (4.3.5). Downloads are still so slow that WinSCP is hardly usable for more than a couple of files. FileZilla has other issues, but is super fast in comparison. Of course I read the FAQ and most of the rest of this thread. Didn't help.
Cheers, Ralf.
has anything happend regarding speed lately? I just installed the latest version (4.3.5). Downloads are still so slow that WinSCP is hardly usable for more than a couple of files. FileZilla has other issues, but is super fast in comparison. Of course I read the FAQ and most of the rest of this thread. Didn't help.
I too verified that there is a speed problem, transferring a file with size 74,319,711, was going to 2 to 3 minutes (local lan, gigabit network)
I installed bitvise tunnelier(as suggested earlier), wow....what a speed difference.
vista(32bit, sp1)
scp 4.0.7
If you look at the debug output of scp (cygwin), they set some socket options and make TCP adjustments:
debug2: fd 3 setting TCP_NODELAY
debug2: callback done
debug2: channel 0: open confirm rwindow 0 rmax 32768
debug2: channel 0: rcvd adjust 2097152
debug2: channel 0: rcvd ext data 44
Sending file modes: C0644 52428800 testfile
window 1998780 sent adjust 98372
debug2: channel 0: window 1982464 sent adjust 114688
Something I have noticed when running WinSCP to a USB hd ... it does an awful lot of head movements during copy ... I just copied a file using Samba, which was about 3-4x as fast, while I could hardly hear the drive doing anything. Doe the same thing with WinSCP, and the head seems to be moving dozens of times every single second ... and no, the drive isn't very fragmented, either ... (that's why I tried the Samba copy, too)
guess one would have to compensate for the "growth" of packets due to encryption - maybe with some change to the MTU generated by WINSCP (e.g. smaller size max 1300 byte?)
I noticed it the other day and had to come back to finalize this post. For some reason WinSCP defaults to SFTP as the transfer protocol. I assumed it would use SCP by default due to the software's name .... switched it SCP now the speeds are excellent. I hope this post gets indexed into Google because the FAQ is not but another post without solution is.
Hope this helps somebody else.
BTW, instead of posting: "Please read FAQ first." You could have posted "Switch to SCP" would have been nicer and more helpful.
What is this speed slider? I have seen reference to it but have downloaded 4.1.2 (among other versions) and can't find it.
Strangely, bringing the "5%-100%" slider down to 5% only cuts the performance in half.
SFTP
I had 6Gb to download and noticed the same thing, In the middle of the download I ran windows update and to my suprise while the update was running the transfer rate increased by 5 fold, when the update was finished the transfer rate went back to slow. I then ran some high CPU tasks and what do you know, the transfer went up each time the Task were running, and went back to slow when they finished.
Sadly, for me, switching between SCP and SFTP makes absolutely no difference. It feels like a software cap, but obviously isn't. Nothing in the FAQ makes any difference.