Crap Gigabit Speeds

[CyberTron]

Well I jumped on the gigabit bandwagon because I wanted to start moving more stuff over to a file server I have setup. The problem is that I'm getting like 15% utilization on my network when sending large files. Here is an example of the best I've done so far...

C:\Downloads\iperf-1.7.0-win32>iperf -c 10.0.0.81 -F slack11.iso
------------------------------------------------------------
Client connecting to 10.0.0.81, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[1912] local 10.0.0.100 port 2197 connected with 10.0.0.81 port 5001
[ ID] Interval Transfer Bandwidth
[1912] 0.0-10.0 sec 185 MBytes 155 Mbits/sec

I am running Encore gigabit cards, a netgear 5 port gigabit switch and some homemade cables that are linking up just fine at 1000Mbps.

Do need to buy premade cables? these cords are pretty good though.

Any help would be much appriciated.

 

[Madwand1]

155 Mb/s ~ 19.4 MB/s. This is not out of the realm of "normal" performance for actual GbE file transfers, and still about double the speed of 100 Mb/s. Sure, double is not ten times!, but it's significant. For common drives, etc., 30 MB/s is reasonable. You're not far from this level if you can do 19 MB/s.

What are the receiving and sending OSs, CPUs, drives and file systems, motherboards, storage controller bus? How's the CPU utilization during transfers?

1. Try it dropping the file and increasing the buffer size, to see the underlying network performance.

E.g. iperf -c server -l 64K -t 12 -i 3

2. Try it enabling jumbo frames = 7K or whatever your Realtek-based NICs support. Use a direct-connect cable (straight-through should be fine for GbE) if your switch doesn't support jumbo frames.

3. If slow (e.g. < 400 Mb/s) after (1),(2), look into networking tweaks for your platforms.

4. Measure local file systems read/write performance. This is not a reliable indicator of max theoretical file system performance over the network, but it's better than nothing and can show some problems.

5. If slow in (4), look into drive subsystem / file system tweaks for your platform.

6. Try different network file transfer protocols, e.g. ftp.

 

[cmetz]

CyberTron, you're using cheap gigabit cards based on the RealTek chipset (blech), Windows, and we haven't even gotten into the rest of your system hardware (PCI chipsets matter, a lot). It's not surprising that you're not maxing out the link.

If you want top network performance, you need to build a system (hardware+software) with good-to-great performance components.

Think of gigabit as "more than 100Mb/s" - that's a more realistic expectation than actually getting 1000Mb/s file transfers.

 

[JackMDS]

CyberTron the "Speed" that you get is about the average that the system yields when using a regular End User system and Client OS (I.e. Not a server OS).

Don not get tempted to replace one or two components (like better NIC) at best it would add few % to the "Speed", or probably would do nothing.

To improve the Network you would have to invest across the board in state of the Art, NIC, Switch, Fast Hard Drive, etc., and switch your topology to a real Server OS.

Even then you would not get 1000 Mb/sec. If you are lucky it would be around 400 to 600 Mb/Sec.

 

[Madwand1]

I've done around 90 MB/s large file transfers using consumer hardware and client OSs, which I think I've posted details on here previously, so I disagree the a 'server OS" and "across the board state of the art" parts are necessary. Of course they wouldn't hurt...

I agree that swapping the $7 NIC for a more expensive one, tempting though it may seem, is not likely to improve performance materially here. It's normal to think that when you don't have stellar file transfer performance when using a new GbE network that the network is to blame, but that's rarely the case (at least with good cables).

E.g., I've measured 70 MB/s large file transfer using a Realtek-based PCI NIC (client OSs, consumer hardware).