Gbit ethernet connection

I just got a 1gbit switch and as far as i know my cables are cat5e. I have noticed when i trasnfer stuff between my pc and other 1gbit devices on my network i always get near exactly 0.5gbit or 500mbit. Does my pc have a dodgy or cheap 1gbit ethernet port or is it the switch?. Could it even be a simple setting somewhere i dont know about?

Blackmesa8

In reply to a post by blackmesa8:

I just got a 1gbit switch and as far as i know my cables are cat5e. I have noticed when i trasnfer stuff between my pc and other 1gbit devices on my network i always get near exactly 0.5gbit or 500mbit. Does my pc have a dodgy or cheap 1gbit ethernet port or is it the switch?. Could it even be a simple setting somewhere i dont know about?

Blackmesa8

A lot of PCs do not have the ability to transfer at speeds reaching 1Gbps because their hard drives do not have a fast enough I/O speed or because they simply are not powerful enough in terms of CPU power or other components not being powerful enough, both the receiving computer and the transmitting computer.

If you are transferring data at around 0.5 Gigabits per second then you are definitely on a 1Gbps network.

For instance; we have been running a 1Gbps network over CAT6a since June 2009 and until June last year we were using a 1 Core, Intel Celeron 3.06GHz computer as a server (Whenever transferring files took place the CPU usage shot straight up to 100% - a tell tale sign that it was going as fast as it could).

We used to get around 65MB/s (520 Megabits per second) even though my PC has a 3GHz Quad Core and our cabling is CAT6a. When we upgraded to a more powerful server last year (Dell 1950) our speeds shot straight up to around the 100MB/s range with bursts of up to 110MB/s.

Remember that both the receiving device and the transmitting device need to be powerful enough to use 1Gbps otherwise you will suffer from reduced throughput.

What hard drives are you using? Are you using a network card? What are the specs of your devices? Do you have any programs on your PC which could be limiting throughput? Also how long is your cabling?

Edited by chris6273 (Mon 20-May-13 05:15:27)

I believe i only have two 1gbit capable devices connected to that switch and that is my pc and and a 1gbit NAS.
I am starting to think it is the NAS holding it back. All cables are 5 meters or shorter, accept a 30 meter cable going to router downstairs but router is only 100mbit anyway.
Everything else is connected directly to the switch in my room.

I did some google research on my NAS since my first post and discovered there are two versions of the same model. An older "version 1" and newer "version 2". It seems people of any setup had issues getting the version 1 of my model NAS to go over 150-250mbit. The 2nd version of my NAS which i think is the one i got people report much higher speeds of 400mbit or more so still far from 1gbit but not too bad. So it very well could be the NAS holding the speed back.

If it is not the NAS and its my pc slowing it down then my pc specs are.
3.2ghz 4 core phenom2 955
8gb 1333mhz ram
I'm using motherboard ethernet which is a "Realtek RTL8168D/8111D Family PCI-E Gigabit Ethernet"
harddrives are
samsung F3 1TB 7200rpm 32mb cache
western digital 2TB green edition 64mb cache 5400rpm
If i transfer files between them two drives internally in my pc windows 7 reports 105 to 118mbyte/s so there not that bad.
The drives in the NAS are also quite good ones a 1tb Seagate 5900rpm one which im unsure of exact model.
And a samsung F4 2TB 5400rpm drive.
I used that samsung F4 in a pc last year and it also managed internal pc transfers to another drive at over 100mbyte/s.

Blackmesa8

I'd say it is your NAS. Not all NAS's are capable of transferring at 1Gbps despite having the 1Gbps interface.

Your PC looks more than powerful enough to transfer at Gigabit speeds. If you are getting Gigabit internally then you should be able to transfer it over the network.

The limit will nearly always be spinning disks as it is not so easy for both sides to read/write from disk at 120+MB/s. Whereas many SSDs for example can easily do this,

You may find smaller files (that fit in the caches) can hit 120MB/s briefly, particuarly if you copy the same file repeatedly so that it is in the cache.

Otherwise you may be able to copy files between RAM (ramfs or tmpfs for unix-like systems.
I have used this approach creating something on both sides of the transfer, using at most 1/4 to 1/3 of memory.

For example mounting say 300MB of RAM based filesystem and using up to 5 copies of the 50MB test files from this site one could test that way without being limited by the disks.

The Realtek cards generally offload less from the CPU (so more is done in software in the drivers) than say an Intel card (more processing can happen on board the NIC),
so on the former you might see high CPU use if alot of small packets-per-second are being transferred, but I'd only expect it to be significant on low power systems.