Suddenly downloads are stuttering

[Vertigo1]

Hi,

Everything has been totally fine until a couple of days ago. Suddenly all my downloads are "stuttering", by which I mean they download in small bursts.
Watching the traffic monitor on my router shows it regularly bursting, downloading for a few seconds then stopping for a few and repeating until the download is finished.

This is on my server so my first test was to try downloading the exact same data from the same Usenet server but with Newsbin Pro on my PC. This worked flawlessly.

I then tried installing SABnzbd on my PC and it also exhibits the problem.

So the same data from the same Usenet server using the same client machine. SABnzbd stutters but Newsbin Pro does not.
And this was fine until it suddenly "broke" two days ago.

I'm at a total loss here, anyone have any ideas?

Thanks.

EDIT: Don't seem to be able to embed images for some reason but this is what my traffic looks like when downloading the 10GB test file:
http://iconia.org.uk/pics/sabnzbdtraffic.png

[Vertigo1]

Anyone?

I've now tried it with a different Usenet provider and it's doing the same thing so clearly not them.

The only constant here is SABnzbd so this is clearly the source of the problem but I have no idea what's wrong, why it suddenly started or how to go about diagnosing/fixing it.

Please help.

PS. This is the traffic graph in SABnzbd:

[sander]

While SABnzbd is NOT doing/downloading anything: In SABnzbd's upper right corner, click on the wrench symbol ("Status and interface options"), then click on first tab Status, and there click on the Refresh Arrow. Post the values of the lower part here.

[Vertigo1]

This bit?

[Vertigo1]

Seems remarkably similar to this old post:

viewtopic.php?t=25072

[sander]

This is after download(s), without restarting SABnzbd? If not: do the 10GB download again, let it finish and then get & post the values again

Xeon, so automatic check questions: SAB straight on Windows on Hardware, or ... Virtual Machine, or VPS, or shared machine, any other layer in between?
F: very fast, but ... built-in, or USB, or NAS, or ... ?

Internet Bandwidth: is 284 Mbps what you buy from your ISP?

[Vertigo1]

This is after repeated test downloads (which all experienced the issue) and without any reboots.

The server is running on a Xeon yes, but my PC is a regular desktop CPU (10700K) and it happens on both machines.
Both are OS on bare metal (Server 2016 and Windows 10 respectively).
F: is a 500GB SATA SSD.

The 284Mbps is not representative. My connection is just over 1Gbps (1150Mbps) and usually maxes at around 138MB/s in SAB. Maybe the reported speed is for a single connection?

The old thread I linked above has got me thinking about whether something is throttling SAB connections somehow but I have no idea what nor why it would suddenly have started.

[Vertigo1]

For reference I just tried the 10GB test download on SAB on my PC.





Disk in this case is an NVMe SSD
Not sure why it's saying the disk speed is the limit.

[Vertigo1]

Okay this is nuts.

I've just tried remoting into my office PC, installed SAB and tried the test 10GB download.
This is obviously on a totally different connection from a different provider, with a nominal speed of 500Mbps.

Doing the same:

[sander]

Not sure why it's saying the disk speed is the limit.

Me neither. But that is what SABnzbd is experiencing while writing the disk.

Usual explanation for sawtooth behaviour:

1) Disk as bottleneck. Explanation: python / OS first caches to RAM (=fast), and as that fills up, and disk writing is too slow: download speeds drops, until RAM is written to disk, and then the speed picks up (writing to RAM), and so on. But: strange, because your disks are fast.
2) as you point out: QoS-settings on router
3) ISP throttling, but less likely to get a sawtooth.

2 and 3 are strange/unlikely, as your other usenet download does not experience it.

EDIT

4) virusscanner kicking. Solution: excluded the SAB download directory

[marklard]

Well, I am having the exact same issue as OP. Started yesterday or day before I believe. Tried it on different computers and having the same 'sawtooth' issue.

[sander]

Maybe you can compare: which usenet provider, which ISP, ... anything common?

[Vertigo1]

Wow, very interesting.

FWIW, I’m using Newshosting via Virgin Media (UK)
That said I’ve tried it on a different connection at work with the same issues.

[sander]

I tried via Newhosting, and I got a straight line, with a mean of 269 MB/s for the 10GB test file:

Downloaded in 39 seconds at an average of 269.5 MB/s

Servers news-nl6.newshosting.com=5.2 GB, news.ams.newshosting.com=5.1 GB

[marklard]

Wow, very interesting.

FWIW, I’m using Newshosting via Virgin Media (UK)
That said I’ve tried it on a different connection at work with the same issues.

I am using NG Direct + NG Ninja, Rogers (CA)