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Trying to find the weak point in my network

Last response: in Networking
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October 4, 2012 5:20:04 AM

Hi everybody,

I'm currently trying to squeeze more performance out of my gigabit network primarily for the purpose of media. I currently have a server pc running a 1tb SATA II, RAID 0 configutation for generating the HD .mkv files and a single receiver doubling as a NAS server. The receiver is matx pc (see bottom for details) running a 4tb SATA II, RAID 0 configuration on the NAS side. The issue I'm having is the low transfer speeds and I'm wondering if it may be my integrated Realtek LAN adapters on both mother boards. I have herd rumors about the south bridge limiting the transfer speeds of integrated peripherals but im not sure if it is correct. I used to get about 55 megabytes/sec transfer rate before changing all the wire runs to a 568B configuration. My transfer speed improved somewhat and 65-70 megabytes/sec was average. I narrowed it down further to my d-link DIR-655 router, so I took it out of the question and replaced it with a d-link DGS-105 switch that claims to have 2gbps capability per port. My transfer speeds are now an average 85-90 megabytes/sec from RAID to RAID. Each of my HDD's should be able to read/write up to 150 megabyte/sec and transfer rates should be even higher off a level 0 data stripping setup should they not? I know at gigabit speeds a network should only attain 125 megabytes/sec so why can't I? Would it be better for me to get a PCI-e intel adapter or possibly a dual port adapter for both the server and NAS? I dont think it is PC capability limitiations as my stuff should be more than powerful enough for this task. I have also entered the driver options for both adapters and have set them to full duplex gigabit mode.

Any help would be greatly appreciated!

Thanks.


SERVER:
ASUS M4A79T deluxe Motherboard
Radeon HD 6870
AMD Phenom II X4 965 o.c 4.1GHZ
8 GB Kingston DDR3 1333mhz
2 (seagate 500 GB 2.5" SATA II HDD) RAID 0


RECEIVER:
GIGABYTE 880GM UD2H
AMD Athlon X2 3.1 ghz dual core
4 GB Kingston DDR3 1333mhz
2 (Seagate SATA II 2TB HDD) RAID 0
October 4, 2012 10:18:33 AM

Well first of all your drive write speeds have pretty much nothing to do with the transfer speed you are getting on your network. That speed is determined by your network hardware. The network ports on the devices connected, the cables the wall plugs and also the switch. For you (or anyone) to attain Gbit speeds on a home network over copper is probably impossible in practice.
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October 4, 2012 12:51:18 PM

One problem is that packets between your devices have IP addresses and other information on them. Since this is all overhead you lose part of your capacity. The way this is fixed is to allow larger packets so that you have fewer of these headers.

You should be able to set all your equipment to run on jumbo frames....but if ALL of it does not support jumbo frames you will have massive issues. It is not a recommended configuration for other than a network dedicated to storage traffic.
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October 4, 2012 4:20:47 PM

ngrego said:
Well first of all your drive write speeds have pretty much nothing to do with the transfer speed you are getting on your network. That speed is determined by your network hardware. The network ports on the devices connected, the cables the wall plugs and also the switch. For you (or anyone) to attain Gbit speeds on a home network over copper is probably impossible in practice.


Thanks for not answering my question. The hdd read and write speeds do play a major part in connectivity because a network is only as fast as its slowest component. I was simply detailing the system for its full capability thus removing the need for one to ask that question later. All components in a network effect speed. What use would a gigabit network be if your hdd only supports 75mbps write speeds like the old gen 1 sata? Sounds like you should spend a little more time learning how computers actually work and why. One of the things I didnt detail in my first post were the 40 megabte/sec transfer rates when moving files from a single drive to a single drive. That alone proves the massive throughput gain in just changing the hdd setup. Also how can it be impossible to attain gigabit speeds at home? Do businesses somehow have secret technology? Are the laws of physics and electrical theory somehow different at work than at home? I doubt it. Copper isnt limited too any speed. It is an electrical conductor. It will always conduct electricity. Our switching technology and programming duplex limit the through put. Thats why cat 5 has been around since 10base t and still worked for 100 base t and 1000 base t. Cat 6 can support up to 10 gigabit connections which is what im running in a 568b configuration as detailed above.
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October 4, 2012 4:21:55 PM

Best answer selected by bghansen2203.
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October 4, 2012 4:26:19 PM

bill001g said:
One problem is that packets between your devices have IP addresses and other information on them. Since this is all overhead you lose part of your capacity. The way this is fixed is to allow larger packets so that you have fewer of these headers.

You should be able to set all your equipment to run on jumbo frames....but if ALL of it does not support jumbo frames you will have massive issues. It is not a recommended configuration for other than a network dedicated to storage traffic.



Thanks very much for the reply. Ill try modifying the packet size asap.
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October 4, 2012 9:31:03 PM

Thanks again for the jumbo frame idea. It works quit well. With 7kb MTU rates my transfer speeds from RAID to RAID average 105-115 megabytes/sec!
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