1Gb Switch - Suggestions to get 1Gb/s?

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mstang1988

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I have several 2208 DLink switches and am only getting 600Mb/s ish on iperf. I've run all permutations of the systems below and the net is about the same. I've tried with multiple machines and believe I have narrowed it down to the switches. At first I was thinking it was the PCI bus causing the slowness but they are the only devices on the PCI buses on those systems. In theory they should not be bound. In practice let's call it 800Mbps so I'm 95% sure it's not PCI. In addition, saw a few reviews with that particular switch that shows the iperf around what I've seen. I will probably back to back wire to test for fun but that's a lot of trouble. Anyway, a couple of questions. What affordable switches out there will do near 1Gb/s in iperf?

Machines:

Freenas 7 Server
- E6600 Intel Dual Core
- 4GB RAM
- Intel 1Gb PCI NIC (don't remember which)

Freenas 8 Server i.e. the replacement
- i5 2400 Quad Core
- 16GB RAM
- Integrated 8168 realtek

Desktop
- i7 970 Hex Core
- 24GB RAM
- Integrated Realtek® 8110SC (On the PCI BUS)
 

praecorloth

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I'd say try a direct connection test between your FreeNAS boxen. Make sure to get a few readings and average them out. Also make sure to have them take turns as the server and client. I'm in the middle of testing my network performance issues, and I noted that there can be a big difference between the iperf readings as server vs client. For example, my FreeNAS box shows I believe it was like 650Mb/s as client, but only 450Mb/s as server.

As for your switch, any switch that says it's capable of 1Gb/s should be capable of such. I've got a Linksys E3000 router that (aside from my FreeNAS box) can pass through 900+Mb/s.
 

mstang1988

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I'd say try a direct connection test between your FreeNAS boxen. Make sure to get a few readings and average them out. Also make sure to have them take turns as the server and client. I'm in the middle of testing my network performance issues, and I noted that there can be a big difference between the iperf readings as server vs client. For example, my FreeNAS box shows I believe it was like 650Mb/s as client, but only 450Mb/s as server.

As for your switch, any switch that says it's capable of 1Gb/s should be capable of such. I've got a Linksys E3000 router that (aside from my FreeNAS box) can pass through 900+Mb/s.

I'm planning on running the direct connect but you would be surprised, it happens pretty often that a NIC/switch do not perform at line speed.
 

andoy31

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Apr 29, 2012
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I have a laptop that has a 1gbps link connection however benchmarking with iperf only gets roughly 600Mbps.. Compared to my mac mini connecting to freenas getting around 960Mbps. (both the laptop and mac are connected to the cheapest gigabit switch i can find ie. tp-link)

Think it might be one of your pc nics, or some driver updates. It'll be good to isolate every component on our setup to try to pinpoint the perf issue.
 

jgreco

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Plenty of supposedly-gigabit switches won't do actual gigabit speeds. That was particularly true early on in the gigabit ethernet cycle... but we're now about 12 years in. Early gigE gear like the Foundry TurboIron/8 was capable of near-saturation because all the switching was done in silicon, but it was insanely expensive. Lower end stuff like the Dell PowerConnect 5012 did some of the work on the system processor, and as a result it could have rather varying performance. That's kind of the situation we find ourselves in today.

Consider something like the Linksys WRT54GL, which has five 10/100 ports. You can get very good switching performance out of it as long as the ports are configured to be switched, but the instant you have packets routed thru the CPU, performance tanks pretty badly.

These days, even many lower-end switches should be able to switch at gigabit speed. You can take note that a gigE port can transmit at most about 1.48Mpps, so if your switch specs claim to handle that per port, you're all good. A lot of them don't seem to bother listing pps anymore (sigh). However, I'd be cautious about assuming that a "router" or "wifi" device will allow you to saturate a gigE.

The real problem in your setup is likely to be "Realtek", which aren't known for high performance. Testing is easy enough: take an ethernet cable and connect directly from the FreeNAS 8 box to the desktop box, and check out what kind of performance you get.
 

mstang1988

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Thanks! I have a couple of 1Gb PCIe Intel NIC's on order so I'll see if that ups the performance. I'm expecting it does. The direct connect did indeed show a small performance increase but not by much (mainly because it was between a PCI Intel NIC and the realtek PCIe. I'll see if the switch can handle 1Gb speeds.
 

jgreco

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It'd be helpful to leave the switch out of the equation until you are getting good performance between the NAS and the desktop.

Direct connections are frequently a bit faster than switched connections, as it will tend to shave some microseconds off the trip, and off the resulting overhead for TCP. The Intel adapters, even many of the cheap desktop ones, tend to be some of the best adapters for gigabit under FreeBSD. If you're getting the server-grade ones, those can also reduce the system load a bit further, but I believe that most features including checksum offload, segmentation offload, etc., are available on all the recent cards, so even a desktop-grade Intel card may perform better than a server-grade card from another vendor. Intel has done a pretty decent job of supporting FreeBSD over the years.
 
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