Download speeds not stable

[sjief]

Goodmorning

I have SABnzbd running on my Synology with fiber connections 500 mbps.

As first I always have a stable constant fast download speed around arount 55 MB/s, but now it just fluctuates a lot and drops to zero. I tested it with multiple nzb downloads.

It's been a while since downloading something, but seems like this is not how it should be.

Somebody an idea what it could be? and where to look to solve?

Best regards,

Sjief

[sander]

The usual 3 steps you should do:

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.

Then, again via Wrench symbol:
click Test download 1GB. After downloading, in history, at the download in the drop down, what was the resulting speed? Example "Download Downloaded in 55 seconds at an average of 22.9 MB/s"
Same for the 10GB test download.

So: 3 things to do for you.

[sjief]

Hi Sander,

Thanks for your reply. Was on vacation, so could not test.

I tested the following:

1) Snelheid van download map 50.2 MB/s /volume1/downloads/incomplete
Snelheid van verwerkte downloads map 58.2 MB/s /volume1/downloads/complete
Internet Bandbreedte 9.9 MB/s

2) 1GB: Gedownload in 24 seconden met een gemiddelde snelheid van 43.8 MB/s

Pretty stable

3) 10GB: Gedownload in 3 min 53 seconden met een gemiddelde snelheid van 45.2 MB/s

Some hiccups, and partly was at 0 MB/s speed

How does this look?
I thought downloads from usenet would always be stable at constant speed or does that not have to be? Especially with fiber

[sander]

Why did you not post the part with System performance (Pystone) ?

Your disks are slow. Probably spinning harddisks?

I would say: great (overall) speeds of 45 MB/s. Matches your 500 Mbps fiber.


Varying download speeds can be caused by:
- slow disks, slow CPU
- missing articles
- slow newsservers
- old posts
- SAB doing other things (reparing, unrarring)

[sjief]

Thanks for reply.

Hereby three tests:

1) Gebruikte buffer 0 B (0 artikelen)
Systeembelasting 5.98 | 5.98 | 6.07 | V=661M R=52M
Systeemprestaties (Pystone) 12158 Intel(R) Atom(TM) CPU CE5335 @ 1.60GHz SSE2
Snelheid van download map 7.4 MB/s /volume1/downloads/incomplete
Snelheid van verwerkte downloads map 82.7 MB/s /volume1/downloads/complete
Internet Bandbreedte 8.1 MB/s 64.8 Mbps

2) Gebruikte buffer 0 B (0 artikelen)
Systeembelasting 5.76 | 5.91 | 6.04 | V=661M R=52M
Systeemprestaties (Pystone) 11490 Intel(R) Atom(TM) CPU CE5335 @ 1.60GHz SSE2
Snelheid van download map 78.8 MB/s /volume1/downloads/incomplete
Snelheid van verwerkte downloads map 85.3 MB/s /volume1/downloads/complete
Internet Bandbreedte 7.9 MB/s 63.2 Mbps

3) Gebruikte buffer 0 B (0 artikelen)
Systeembelasting 5.76 | 5.90 | 6.03 | V=661M R=52M
Systeemprestaties (Pystone) 13004 Intel(R) Atom(TM) CPU CE5335 @ 1.60GHz SSE2
Snelheid van download map 75.4 MB/s /volume1/downloads/incomplete
Snelheid van verwerkte downloads map 85.3 MB/s /volume1/downloads/complete
Internet Bandbreedte 8.8 MB/s 70.4 Mbps

Is it due to poor performance you think?

[sander]

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Systeembelasting 5.98 | 5.98 | 6.07 | V=661M R=52M

Overloaded system

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Systeemprestaties (Pystone) 12158 Intel(R) Atom(TM) CPU CE5335 @ 1.60GHz SSE2

Intel doesn't know the CE5335, but if you have a Synology: I only see CE5335 in two models from around 2014. That is 9 years old. Even then, an Atom was slow.

Pystone of 12.158? That is extremely low. But, like I said: you must get the Wrench info while SAB is not doing anything else (not downloading, unpacking, etc). Did you do that? If so: your CPU is extremely slow.

[sander]

In general, wibbly-wobbly aka fluctuating speeds are often caused by low spec hardware. (Or a wifi connection; use wired instead)

The good news: SABnzbd will tell you after a download, via Wrench. For example:

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Download speed limited by  CPU (401x) Disk speed (539x)

... meaning the download speed was limited by the CPU (401 times since SAB's start) and Disk (539 times since SAB's start)

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System performance (Pystone)  5459 

... which is a very bad performance, caused by old and/or underpowered hardware. A current Celeron will give you arond 100.000 pystone, a current i3 will give you 300.000 pystone

If you want stable, high-speed dowloads, you need good hardware

[serlex]

Hello, I was redirectect here by @sander, from my original post (I cannot post the link because I'm a new user :-/ forums.sabnzbd. org/ viewtopic.php?t=26082 )
I'm suffering from a similar issue (maybe?) but I'm not so sure it's the same because my wrench stats are better

[sander]

Hi Serlex.

You posted

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Download speed limited by CPU (50x) Disk speed (60x)

So SAB reports your CPU was 50 times the bottleneck and your Disk 60 times.
What you can do: restart SABnzbd to clear the counter. Then do 10GB test download via Wrench, and then check SAB's report again

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System performance (Pystone) 51378 Intel(R) Celeron(R) J4125 CPU @ 2.00GHz SSSE3

51.000 is not too great. Half of my 2019 Celeron. And my 2022 i3 reports 350.000
Wait: I hope you did that report while SAB was not doing anything? You should

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Download folder speed 42 MB/s /data/usenet/incomplete-sabnzbd
Complete folder speed 43.6 MB/s /data/usenet

Slow too (well, slow if you have gigabit = 100 MB/s). Probably spinning disks?

[serlex]

Thank you for reviewing my case!

I restarted the container and ran the Wrench again. These are the results before running the 10 GB test

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IPv6 address  None
Nameserver / DNS Lookup  OK
Used cache  0 B (0 articles)
System load  0.42 | 0.36 | 1.04 | V=90M R=65M
System performance (Pystone)  50077  Intel(R) Celeron(R) J4125 CPU @ 2.00GHz SSSE3
Download folder speed  45.3 MB/s  /data/usenet/incomplete-sabnzbd
Complete folder speed  47.8 MB/s  /data/usenet
Internet Bandwidth  74 MB/s  592 Mbps

These are the results after the 10GB test file (which also suffered from speed drops)

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Used cache  0 B (0 articles)
System load  2.21 | 4.48 | 3.26 | V=110M R=79M
Download speed limited by  CPU (516x) Disk speed (132x)
System performance (Pystone)  49927  Intel(R) Celeron(R) J4125 CPU @ 2.00GHz SSSE3
Download folder speed  19.1 MB/s  /data/usenet/incomplete-sabnzbd
Complete folder speed  20.3 MB/s  /data/usenet
Internet Bandwidth  73.7 MB/s  589.6 Mbps

[sander]

Download speed limited by CPU (516x) Disk speed (132x)

... and that after just one 10GB confirms your bottleneck CPU and Disk. That is limiting and fluctuating your speeds. So ... put in an SSD on which SAB can work?

Furthermore: let SAB focus on downloading:
Config -> Switches: Direct Unpack: ... turn OFF
Config -> Switches: Pause Downloading During Post-Processing ... turn ON
... does that give more stable speeds?



In your original post, you said you use docker. Python on docker in unpriviliged mode, lowers the CPU performce with 25-40%. That explains the low pystone of your CPU. So run SABnzbd natively on your NAS?

[sander]

FWIW:

On my low-spec system (slow CPU, slow disk) I also get very fluctuating speeds

Wrench info: Download speed limited by CPU (345x) Disk speed (194x) ... so ... yeah, getter better CPU & Disk.

[sander]

Ah ... I found a way on my low-spec hardware to make the download speed super stable.

I did a test download. Very fluctuating. ... Mean speed as reported by SAB: 4.6 MB/s.
Based on that, I limited the speed in SAB to 2MB/s and later on to 4 MB/s
Furthermore: the two settings above.

Result: rock stable download speed on my low-spec hardware:



EDIT:

And supercool: the SAB Wrench does not say anything "limited by".

[serlex]

(I'm currently away on a trip but will post later after applying your latest inputs)

[sander]

SAB bandwidth not set, result is fluctuating speed ... between KB/s to 6.1 MB/s:

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2023-01-03 14:15:05,459::DEBUG::[bpsmeter:354] Speed: 3.4 MB/s
2023-01-03 14:15:10,678::DEBUG::[bpsmeter:354] Speed: 1.7 MB/s
2023-01-03 14:15:15,741::DEBUG::[bpsmeter:354] Speed: 800 KB/s
2023-01-03 14:15:21,753::DEBUG::[bpsmeter:354] Speed: 1.1 MB/s
2023-01-03 14:15:34,898::DEBUG::[bpsmeter:354] Speed: 507 KB/s
2023-01-03 14:15:39,909::DEBUG::[bpsmeter:354] Speed: 4.6 MB/s
2023-01-03 14:15:45,546::DEBUG::[bpsmeter:354] Speed: 2.5 MB/s
2023-01-03 14:15:50,774::DEBUG::[bpsmeter:354] Speed: 1.5 MB/s
2023-01-03 14:15:55,823::DEBUG::[bpsmeter:354] Speed: 618 KB/s
2023-01-03 14:16:00,872::DEBUG::[bpsmeter:354] Speed: 246 KB/s
2023-01-03 14:16:05,919::DEBUG::[bpsmeter:354] Speed: 98 KB/s
2023-01-03 14:16:10,968::DEBUG::[bpsmeter:354] Speed: 39 KB/s
2023-01-03 14:16:16,008::DEBUG::[bpsmeter:354] Speed: 16 KB/s
2023-01-03 14:16:21,069::DEBUG::[bpsmeter:354] Speed: 6 KB/s
2023-01-03 14:16:26,130::DEBUG::[bpsmeter:354] Speed: 2 KB/s
2023-01-03 14:16:31,168::DEBUG::[bpsmeter:354] Speed: 5.1 MB/s
2023-01-03 14:16:36,188::DEBUG::[bpsmeter:354] Speed: 3.5 MB/s
2023-01-03 14:16:41,231::DEBUG::[bpsmeter:354] Speed: 6.1 MB/s

today, with SAB bandwidth limited to 2 and later 4 MB/s: rockstable

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2023-01-04 15:30:12,330::DEBUG::[bpsmeter:354] Speed: 2.0 MB/s
2023-01-04 15:30:17,336::DEBUG::[bpsmeter:354] Speed: 2.0 MB/s
2023-01-04 15:30:22,344::DEBUG::[bpsmeter:354] Speed: 2.0 MB/s
2023-01-04 15:30:27,349::DEBUG::[bpsmeter:354] Speed: 2.0 MB/s
2023-01-04 15:30:32,350::DEBUG::[bpsmeter:354] Speed: 2.0 MB/s
2023-01-04 15:30:37,354::DEBUG::[bpsmeter:354] Speed: 2.0 MB/s
2023-01-04 15:30:42,362::DEBUG::[bpsmeter:354] Speed: 2.0 MB/s
2023-01-04 15:30:47,363::DEBUG::[bpsmeter:354] Speed: 2.0 MB/s
2023-01-04 15:30:52,365::DEBUG::[bpsmeter:354] Speed: 2.0 MB/s
2023-01-04 15:30:57,373::DEBUG::[bpsmeter:354] Speed: 2.0 MB/s
2023-01-04 15:31:02,383::DEBUG::[bpsmeter:354] Speed: 2.0 MB/s
2023-01-04 15:31:07,388::DEBUG::[bpsmeter:354] Speed: 2.0 MB/s
2023-01-04 15:31:12,391::DEBUG::[bpsmeter:354] Speed: 2.0 MB/s
2023-01-04 15:31:17,399::DEBUG::[bpsmeter:354] Speed: 2.0 MB/s
2023-01-04 15:31:22,416::DEBUG::[bpsmeter:354] Speed: 2.2 MB/s

2023-01-04 15:31:27,423::DEBUG::[bpsmeter:354] Speed: 4.0 MB/s
2023-01-04 15:31:32,426::DEBUG::[bpsmeter:354] Speed: 4.0 MB/s
2023-01-04 15:31:37,437::DEBUG::[bpsmeter:354] Speed: 4.0 MB/s
2023-01-04 15:31:42,446::DEBUG::[bpsmeter:354] Speed: 4.0 MB/s
2023-01-04 15:31:47,448::DEBUG::[bpsmeter:354] Speed: 4.0 MB/s
2023-01-04 15:31:52,453::DEBUG::[bpsmeter:354] Speed: 4.0 MB/s
2023-01-04 15:31:57,457::DEBUG::[bpsmeter:354] Speed: 4.0 MB/s
2023-01-04 15:32:02,462::DEBUG::[bpsmeter:354] Speed: 4.0 MB/s
2023-01-04 15:32:07,467::DEBUG::[bpsmeter:354] Speed: 4.0 MB/s
2023-01-04 15:32:12,475::DEBUG::[bpsmeter:354] Speed: 4.0 MB/s
2023-01-04 15:32:17,477::DEBUG::[bpsmeter:354] Speed: 4.0 MB/s
2023-01-04 15:32:22,485::DEBUG::[bpsmeter:354] Speed: 4.0 MB/s
2023-01-04 15:32:27,492::DEBUG::[bpsmeter:354] Speed: 4.0 MB/s
2023-01-04 15:32:32,499::DEBUG::[bpsmeter:354] Speed: 4.0 MB/s
2023-01-04 15:32:37,504::DEBUG::[bpsmeter:354] Speed: 4.0 MB/s
2023-01-04 15:32:42,511::DEBUG::[bpsmeter:354] Speed: 4.0 MB/s