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Post subject: Connection speed
 Posted: Jul 11, 2008 - 08:21 PM
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Joined: Dec 04, 2006
Posts: 136
Status: Offline
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I'm curious about connection speeds, and why mine seem so low. My setup is a Linsys 100mb router and a dlink gigabit switch connecting a sidux machine w/gigabit NIC card and an iMac with the same. Doing "ethtool eth1" shows a gigabit connection speed as do the leds on the switch. The iMac also shows a gigabit connection. However moving a big file shows a transfer speed of only about 20 mb/s. When I connected both machines directly to the Linksys 100mb router, the transfer speed dropped to about 7.8 mb/s.
I thought I would get higher transfer speeds. Not sure if this is normal or if there's an issue I need to learn more about. Any insights?
thx,
feffer |
_________________
To whom much is given, much shall be required.
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Post subject: RE: Connection speed
Posted: Jul 11, 2008 - 08:52 PM
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Joined: Nov 25, 2006
Posts: 2570
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It depends on a lot of things...
- the used protocol and its protocol overhead (sftp/ scp or smbfs/ cifs is a lot slower than ftp/ nfs)
- the type of interface used for the GBit/s NIC (PCIe or internal controller bus is a lot faster than (onboard) PCI)
- the switch's backplane
- the ethernet cable CAT6 is a must, unless your connection is really short when CAT5e "might" be sufficient (all 8 leads need to be connected, cheap cables from the 100 MBit/s era often aren't)
- the harddisk performance (old ~40-60 GB disks simply don't allow more than 18-20 MB/s throughput on their own)
- the general system speed
An old sub-1GHz system with PCI cards might not allow more than ~16-18 MB/s over ftp://, a current system with controller-bus or PCIe ("onboard" itself doesn't say anything about the bus it connects to) will allow up to ~50 MB/s over ftp:// in real life - and topping 100 MB/s in purely synthetic benchmarks (which simply aren't achievable under real life circumstances). |
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Post subject:
Posted: Jul 11, 2008 - 09:35 PM
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Joined: Dec 04, 2006
Posts: 136
Status: Offline
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Thx slh. After posting, I read an article that also outlined some of the issues you cited. I "think" I have cat 5e cable, so I should replace it with known cat-6. The iMac is pretty new, but the PC is an older P-4 on which I replaced the 100 MB NIC with a gigabit cart, so I guess the bus speed and other things on the mobo might be an issue. The PC is a 2 Ghz system though.
I did try rebooting the PC into WinXP though and got a better transfer speed: a 1 gig file in prox 30sec (about 34 MB/s). More than 50% better than when booted into sidux. I think I must have some setting limiting me here.
I'm using samba for these connections, and there's definitely a lot I don't know about samba!
Thx,
feffer |
_________________
To whom much is given, much shall be required.
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