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Gigabit networking part 2 + Thecus N4100+ part 2

The first parts of this post can be found here and here.

I've combined part 2 of both of these posts as ultimately the problems I had getting Gigabit network speeds and the performance of the Thecus were interrelated.

After my previous unsuccessful attempts at improving my Gigabit speeds I didn't completely give up and over the next few months I tried a few more things, the main change being moving everything over to Cat6 cabling, but as with most of my other changes I didn't see any massive improvements worthy of the Gigabit name.

During my travels I'd previously read about the impressive speed of the Intel NIC's and especially how well they performed when paired together, which got me to thinking 'what if you used the same NIC's in every PC?', I was sure I'd read something about this somewhere as well but as per usual my ninja Google skills let me down (back to ninja training school for me!) and I couldn't find the article I'd read.

A bit more Googling around and it seemed to me that the Intel PRO/1000 GT was getting some good reviews and more importantly the high speeds I was after, but at around £25 each (I needed 4 of them) I was a bit hesitant to commit down a path that I wasn't sure would yield any positive results. I managed to remain hesitant and keep my gadget spending in check for at least a couple of weeks, which is pretty good for me, before I finally buckled and 'thought to hell with it' and placed the order.

As per usual, eBuyer's excellent service meant that the NIC's arrived nice and quickly so I was able to get them installed into a couple of machines to test with. I chose the kitchen media center and the lounge media center since both PC's were easily accessible and they were both plugged into the same switch. Once the NIC's and drivers were installed I made sure I disabled the old NIC's to avoid any conflicts, enabled 4k jumbo frames, prepared a 1gig test file and loaded up FastCopy.

When those first test results came in I was like a kid at Christmas, wow, I was getting around 45Mb/s which I had never, ever got before. A few more tests in both directions confirmed the first result and I was very happy, I'd justified the money I'd spent (the missus might say otherwise of course :-)). I played around with the jumbo frame size, increasing it to 8k and then 16k, testing with a batch of smaller files as well as a single large file, there was hardly any difference seen with the large file, but with the smaller files the performance was worse with the higher frame sizes, so I stuck to 4k.

I then proceeded to install the other 2 NIC cards in the server and the kids media center, performing similar tests to what I had already done and on all occasions I got similar results in the 40-50Mb/s range. I was so pleased with everything that I begun to wonder what the performance would be like with the Thecus NAS, which up until this point had been sitting in the box it came in gathering dust.

Since I'd installed the 500gig drives that were originally meant for the Thecus into the server I didn't have any spare SATA drives that I could use to test with. I decided that it was about time I finally used the Thecus rather than just leaving it there wasting money so I ordered a new 1TB Samsung drive which would then be used primarily for backup purposes.

When the drive arrived I once again unboxed the Thecus and installed the drive, I then set the NAS up like I had done many times previously, making sure I enabled 4k jumbo frames to match my new NIC's. Testing the NAS didn't yield the 40-50Mb/s results that the new NIC's had done but then again I never expected it to, what I did get was speeds of around 20Mb/s which based on all the information I could find was pretty much the maximum I could expect from this NAS drive so I was happy, at least now I had some fairly decent file transfer times.

You may be reading this and thinking to yourself that Gigabit has a maximum speed of around 100Mb/s so why is this guy so happy with 40-50Mb/s? The answer is actually quite simple, all of my tests involved reading and writing to a hard disk, with most modern hard disks having a maximum throughput of around 75Mb/s. Don't believe me? After all SATA 300 is supposed to offer 300Mb/s isn't it? Have a look at this great article series on SmallNetBuilder entitled How To Build a Really Fast NAS, it really is worth reading all of the parts especially as it's near the end that they give you the hard drive benchmarks. Taking this into account and the fact that I have a mixture of old IDE drives and not so new SATA drives coupled with a range of CPU's means that achieving 40-50Mb/s is pretty good in my book.

Here's a summary of the setup that achieved the best speeds for me (your mileage may vary):

  • All NIC's same make and model
  • Cat6 cabling
  • 4k Jumbo frames
  • Gigabit switches

No other changes I made significantly affected the transfer speeds. I haven't made any other changes since installing the new NIC's and I've been living with a reasonably fast network ever since, so I'm a happy bunny.