Slow network Fresh CentOS 8 (With 7 it was fast).

Issues related to hardware problems
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poing
Posts: 2
Joined: 2019/10/06 13:14:11

Slow network Fresh CentOS 8 (With 7 it was fast).

Post by poing » 2019/10/11 12:29:52

After 15 years, I picked up Linux again with CentOS 7. Got a Plex Media server with Samba running fairly easy. On this system, i was very surprised about the network speed when I copied a file from my performant Windows SSD to a 6 year old PC's disk (haswell) and an USB3.0 SS drive. I got speeds of 900Mbit/s, I was so surprised that I monitored in both Windows, Cockpit and I timed it.

This was the way to go for my home server, I played and learned for CentOS 8 to come and install it from scratch. Unfortunately, first thing I notice is that I'm not hitting the speeds, I get 100Mbit/s.

Disk speeds (both internal and USB3) are 130MB/s, I didn't change any cables, output below claims to support 1000Mbit/s.

Any idea's?

- CentOS 8 Minimal Environment with Standard add-on (for the standard installation of CentOS Linux).
- Added Samba, that's it for now.
- The network Card: Intel Corporation Ethernet Connection (3) I218-LM (rev 03)
- Output of the card:

Settings for enp0s25:
Supported ports: [ TP ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Supported pause frame use: No
Supports auto-negotiation: Yes
Supported FEC modes: Not reported
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Advertised pause frame use: No
Advertised auto-negotiation: Yes
Advertised FEC modes: Not reported
Speed: 1000Mb/s
Duplex: Full
Port: Twisted Pair
PHYAD: 1
Transceiver: internal
Auto-negotiation: on
MDI-X: off (auto)
Cannot get wake-on-lan settings: Operation not permitted
Current message level: 0x00000007 (7)
drv probe link
Link detected: yes
Last edited by poing on 2019/10/18 07:53:23, edited 1 time in total.

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TrevorH
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Re: Slow network Fresh CentOS 8 (With 7 it was fast).

Post by TrevorH » 2019/10/11 15:41:33

How are you testing? I'd start by using iperf3 to test only the network connection - it needs to be installed on two machines, one server, one client. That should tell us if the problem is the network itself or something else.
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hunter86_bg
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Re: Slow network Fresh CentOS 8 (With 7 it was fast).

Post by hunter86_bg » 2019/10/13 20:05:18

Also, you can set the MTU in NetworkManager to Jumbo frames if your switch/router supports them.

poing
Posts: 2
Joined: 2019/10/06 13:14:11

Re: Slow network Fresh CentOS 8 (With 7 it was fast).

Post by poing » 2019/10/18 08:11:34

Now it works :shock:
1. I updated the network card driver,
2. Updated CENTOS
3. Swapped cables

Didn't help, I didn't have time to learn iperf3 or how to set jumbo frames yet but now it just works. Copy 30Gb in exactly 5 minutes, that's 100Megabyte/s. There was a blackout, maybe the router needed a reset? Thanks anyway and I'll check out the jumbo frames, but I'l already satisfied with the speed.

BShT
Posts: 120
Joined: 2019/10/09 12:31:40

Re: Slow network Fresh CentOS 8 (With 7 it was fast).

Post by BShT » 2019/10/22 17:32:21

yum install iperf3

iperf3 -s ------ on server
iperf3 -c ipOfServer ------ on client

there is nothing to learn, just take care of your firewall rules

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