CentOS

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

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.

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

Now it works
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.

yum install iperf3

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

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