Download Performance 'saw-tooth'

[flux]

Hi all,

First time here but I've done everything I can think of and have run out of ideas. So, I have Sab running on the latest version on a dedicated Windows mahcine with the following:

- 220 thounsand or so Pyrostone score
- 8GB of RAM
- Writing to an SSD, with write speed of around 100MB
- i5 qaud core
- 5 or so servers setup with 20 connections on each

I have no problem hitting max speed for my line, not a problem. But then, it will drop off and bring it back to max speed again. E.g. It will run at a constant 26MB/s and then immediately drop to 16MB/s or so and then work it's way back up to 26MB/s. My download group looks like sharks teeth...

It does this roughly every minute or so, without fail and not faster or slower, always on time.

Anyone had similar issues or have any suggestions? I would greatly apprecaite it.

[safihre]

What version of Sabnzbd are you using? At least 2.0.x?
Did you read and apply https://sabnzbd.org/wiki/advanced/highs ... ading.html

[flux]

Hi safihre,

Thanks for getting back to me.

I can confirm I'm using version 2.0.1 [be5bebb].

I made all the chagnes in the WIKI article you suggested when this first started happening.

I can't seem to find sabyenc as described in the first step but I did install from the standard Windows installer.

I've got my Article Cache set to 1G.

My Logging has always been set to Errors/Warnings.

I used to have lots of connections but reduced them to make sure that wasn't the problems.

I'm unsure how to change the SSL Ciphers.

My CPU and disk write speed is way above what it needs to be.

[safihre]

In Config > Switches, set SSL Cipher to 'RC4-MD5' (without the quotes).
Restart SABnzbd

[flux]

I've changed the SSL cipher, still having the same issues.

[flux]

Don't suppose anyone has any more thoughts on this?

[safihre]

Can you try 2.2.0? Just download the Standalone version, which you can just unpack anywhere and run. It will use the settings from your regular sabnzbd without having to overwrite it.

[flux]

Hi,

Just tried 2.2.0 beta and the same things appears to be happening. Are we safe to assume there is a high likelyhood it's my internet connection, hardware or usenet server?

It's frustrating as this used to work without issue at max speed.

[flux]

As an update, I have tried looking through the logs but they don't track speed from what I can see so that isn't going to help.

[safihre]

Maybe you can watch memory, disk and cpu usage in the task manager? How does it look during the drops? Is there lots of disk activity or cpu activity?

[flux]

Hi Safihre,

Thanks for the advice. I will give what you mentioned RE watching memory etc. for the next few days and see if I can make a link. Really appreciate all your help thus far. :-)

[battlechaser]

has anyone made headway with this issue i'm seeing the same thing;

[safihre]

You did everything that is listed in the Highspeed downloading page? The cache size, disabling logging, making sure you have Sabyenc?
If that's the case, your hardware is just not fast enough.
What you see is that it fills the cache fastand then empties it while slowing the downloading speed to not overflow the memory.

[sander]

I have no problem hitting max speed for my line, not a problem. But then, it will drop off and bring it back to max speed again. E.g. It will run at a constant 26MB/s and then immediately drop to 16MB/s or so and then work it's way back up to 26MB/s. My download group looks like sharks teeth...

It does this roughly every minute or so, without fail and not faster or slower, always on time.

I would say this is classic TCP Sawtooth behaviour. Google gives a lot of descriptions. It happens when TCP detects losses; it throttles back then.

EDIT
When you download a 1GB file via HTTP or FTP (so: with your webbrowser or wget or curl, not SABnzbd), do you also get the sawtooth with the max at linespeed?
/EDIT

You could use SAB's max bandwidth setting (and it at 80% or so) to see if that avoids TCP losses and thus throttling back.

[safihre]

Similar story on Reddit, the other user sees this not only on sabnzbd, but also on other services like the browser.
Coild also be QoS being active from your router:
https://www.reddit.com/r/usenet/comment ... _going_up/