Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

m3rob

macrumors member
Original poster
Dec 28, 2010
41
7
1. I have two 4,1 Mac Pros with a 4 hard drive raid setup inside each computer which Reads and Writes at about 400 MB/s. When I transfer files between the computers with one ethernet cable connected directly from Ethernet Port 1 on each machine I get about 90 MB/s transfer. But when I connect Ethernet Port 2 on the machines with their own cable to my Airport extreme to get internet access I get speeds of about 10 MB/s. Is there a way to prevent the speeds from dropping without having to disconnect the ethernet port which is connected to the Airport extreme each time?


2. I was also wondering what is the fastest way to transfer large video files from one computer to the other. Is there any other method I could use to transfer files between the computers that would yield faster speeds than 90 MB/s?

Thanks!
Rob
 
1. I have two 4,1 Mac Pros with a 4 hard drive raid setup inside each computer which Reads and Writes at about 400 MB/s. When I transfer files between the computers with one ethernet cable connected directly from Ethernet Port 1 on each machine I get about 90 MB/s transfer. But when I connect Ethernet Port 2 on the machines with their own cable to my Airport extreme to get internet access I get speeds of about 10 MB/s. Is there a way to prevent the speeds from dropping without having to disconnect the ethernet port which is connected to the Airport extreme each time?

Gigabit Ethernet has a theoretical maximum of 125 MB/s (125,000,000 bytes per second - network and disk performance is measured in decimal notation, not MiB/sec).

In the real world, some of those bytes are used by protocol overhead, and some are lost to latency. I've seen real world disk to disk data rates of 110 to 115 MB/s using block protocols (CIFS, iSCSI).

You don't say what tools you are using to transfer the files - but 90 MB/sec (that is 90,000,000 bytes per second) is pretty good. (And if you're incorrectly using MiB/sec - 90 MiB/sec is about 94 MB/sec, which is even better.)

In other words, the best improvement that you could hope for is in the 10% to 15% range - probably not worth any great effort to improve. Will reducing a 60 minute file transfer to 55 minutes change your life?

And, WiFi always sucks compared to a copper connection. A shared bus subject to cross-talk and adjacent channel and other interference vs. a full-duplex point-to-point link to a crossbar switch.... When my husband and I remodeled our house, we put in one of the +500Mbps multi-band 802.11* access points - and Cat6 to every room (often multiple - there are 4 Cat6 copper drops in the kitchen). WiFi sucks - only visitors with Galaxies use it.


2. I was also wondering what is the fastest way to transfer large video files from one computer to the other. Is there any other method I could use to transfer files between the computers that would yield faster speeds than 90 MB/s?

Thanks!
Rob

If you want to spend a thousand or so dollars per port (to several tens of thousands) there are 10Gbps and 40Gbps and 100Gbps cards available. Probably not with Apple OSX drivers, though. And the switches cost more than most luxury cars. (I bought two switches, and a nice new car. Car was definitely cheaper.)
 
Last edited:
Crete a point to point network using FW800 cable. The Mac can route IP packets over FW800. You can remain counted to WiFi at the same time.

I have read that it can do the same with Thunderbolt but I've not tried it.

The absolute fastest way to to move data is to swap a 4TB drive from one mac to the other if you are fast and can swap a cable in one second flat then you have a 4TB/Second transfer rate ;-)

I know BSD UNIX (and I assume Mac OS X) can support multiple parallel network connections. Four gigabyte ethernet cables would be fast if you can get Mac OS X to load balance over the four cables.
 
On this subject, what about using apples fibre channel cards?

Is there some way to connect 2 powermacs together directly using fibre without needing a hub? like a network?

The only use I know of for apple fibre is for external drives or the xserve raid. Is that really all it can do?
 
Are you cloning the computer or moving?

If you're moving you can swap harddrives. Hardware is all the same in Mac's and there are no serial numbers or any copyright protection on OSX.

If you are cloning, go to the computer store and buy an Ethernet "Crossover" cable. It's a CAT5 cable that has the orange and green wires swapped on the left hand side...normally you would have the same color on the left hand side.

Put this into the 2nd Ethernet plug on each one and go into Settings>Network and for Ethernet 2 give them a unique local IP address that is not in the range of your household address pool.

Computer 1
192.168.255.1

Computer 2
192.168.255.2

Go into Advanced settings and change the Frame size to 9000 (Jumbo frame).

Then connect from one computer using the IP address of the other.

This will give you about 100-105MB/s sustained if the drives can support it (primarily the write speed, read speeds will be fine).

This is the fastest speed you will get with the smallest investment.

EDIT: Do not be tempted by copying everything to an external drive. Because even though it might write faster then 100MB/s, remember you still have to transfer it to the target computer. So you would have to have DOUBLE the speed of your Ethernet to make it worthwhile....which you are not going to get without some investment (USB3 or eSATA card...plus a drive that can support 200+MB read & write).

800px-Vergleich_2von2_Crossoverkabel.jpg
 
Take HDD form machine one and put them in machine 2... Tada... Fastest data transfer between 2 mac :p
 
The unique IP addressing is probably the key here -- I suspect that what's happening in the OP's slow case is that the traffic is being routed through the home network, rather then direct box to box. Defining a separate IP for the direct connection is one way to do it, and probably the simplest. (Another way would be to use route add -host <target-ip> -iface <ethernet interface>, but then you have to issue the route command after each restart, or fool around with startup items to make it permanent.)
 
Thanks for the replies everyone! I will do some testing and let you know what I find out!

Thanks so much again!

Rob
 
Are you cloning the computer or moving?

If you're moving you can swap harddrives. Hardware is all the same in Mac's and there are no serial numbers or any copyright protection on OSX.

If you are cloning, go to the computer store and buy an Ethernet "Crossover" cable. It's a CAT5 cable that has the orange and green wires swapped on the left hand side...normally you would have the same color on the left hand side.

Put this into the 2nd Ethernet plug on each one and go into Settings>Network and for Ethernet 2 give them a unique local IP address that is not in the range of your household address pool.

Computer 1
192.168.255.1

Computer 2
192.168.255.2

Go into Advanced settings and change the Frame size to 9000 (Jumbo frame).

Then connect from one computer using the IP address of the other.

Manually setting up the ip address as described in this post fixed the problem where I was getting a huge slowdown if I had another cable connected to my Airport. Thanks so much!

Now I get speeds of about 110 MB/s when dragging files from one computer to the other using Apple Remote Desktop drag and drop function. Which is a big improvement!

I have another question that I haven't mentioned yet... When I connect to the Mac Pro through the shared location in the finder window sidebar and choose Connect As... and then drag and drop from the two finder windows... the speed is much slower and it even stops every few seconds and then starts up again, but never reaching higher than about 80 MB/s. So my problem is solved by just using Remote Desktop, but is it possible to make the finder Shared connection as fast and as constant as the Remote Desktop drag and drop?

Thanks again everyone!
 
On this subject, what about using apples fibre channel cards?

Is there some way to connect 2 powermacs together directly using fibre without needing a hub? like a network?

The only use I know of for apple fibre is for external drives or the xserve raid. Is that really all it can do?

powermacs ≠ Mac Pro
 
On this subject, what about using apples fibre channel cards?

Is there some way to connect 2 powermacs together directly using fibre without needing a hub? like a network?

The only use I know of for apple fibre is for external drives or the xserve raid. Is that really all it can do?

No, but on that topic there is a protocol called iSCSI that emulates SCSI over a network. While the speed itself will not be any different, the advantage to this is that you can have a separate computer that has lots of storage, but the computer connecting sees it as a native hard drive attached to the system. So you get some extra freedom that comes with using a "real" hard drive instead of a traditional network protocol like SMB or AFP.
 
Crete a point to point network using FW800 cable. The Mac can route IP packets over FW800. You can remain counted to WiFi at the same time.

I have read that it can do the same with Thunderbolt but I've not tried it.

I used to do this over FireWire 800 and it was blazing fast back in the day. If you are using a 192.168. network on your WiFi you just set up the direct network connection as a 10.0. net instead.

I Googled it and there are articles that suggest that you can indeed do it over Thunderbolt.

http://arstechnica.com/apple/2013/10/os-x-10-9-brings-fast-but-choppy-thunderbolt-networking/
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.