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Thru put speed of 1Gig ethernet cable?

I have a gigabit switch ports connected to my server (a pretty new server with RAID 5 storage), my question is how fast can I get if I transfer a big file from my network to that server?


Thanks.
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SJCA
Asked:
SJCA
4 Solutions
 
music2myear1Commented:
Theoretically the file will transfer at at one Gigabit per second. In storage terms we talk about bytes more than bits, though. A byte is 8 bits, so by extension, you'd get a Gigabyte transfered every 8 seconds.

However, you're dealing with more than just the network cables ability.

Can the systems at both ends of the network handle sending and receiving that much data that quickly?

In reality, if you are running a well configured network with routing, each transaction (ie file copy or move or access) will run at the speed of the slowest member participating in the transaction.

And to top it all off, there is over head on the networ. Network communication occurs primarily in packets, which have a certain amount of space allocated for data, and a certain amount of space allocated for headers and footers that may vary greatly in size.

So you may have to multiply the size of the file you're transfering by 30% or more to indicate the amount of communication the network has to do to get that file from point at to point b.

And systems on the network never really stop talking to each other. Your system time service may be talking to the time server, update service may be talking with the update server. Each program that is accessing the network is using a little bit more of the bandwidth.

So any given file transfer will operate at the speed of the slowest participant and will be able to use only a certain fraction of the total network bandwidth.

Using a network speed test application can help get an idea of your realistic throughput, though I'm not personally familiar enough with one to make a recommendation.
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edster9999Commented:
The speed bottle neck is not in the network but in how fast you can store the data.
The drives write speed is far slower than the network speed.
Modern raid arrays or even just modern individual drives have cache memory to help. But with a constant flow like this the cache will be full within seconds so it all goes down to write speed.
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DavidCommented:
Real-world, I take it you wouldn't be asking the question if you were getting 100+ MB/sec.
So the bottleneck is R5 write speed.  If you have SATA drives, and no write cache then it could very well be in the 5-25MB/sec range.
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music2myear1Commented:
Do a google search for local network speed test and you'll find several results that look promising regarding finding a reasonable baseline for your network connection.

In the office I work at, we have a well configured Gigabit network.

Copying multi-gigabyte files from one workstation to another goes very quickly. Though we are running Windows XP, which is admittedly, very slow at network file transfers.

Files up to 5 Gigabytes will usually copy in 2 minutes or less. Much larger, though, and it can take up to half an hour.
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rfc1180Commented:
>my question is how fast can I get if I transfer a big file from my network to that server?
This is what is called goodput and typically is the only way to involve the disk read and write speeds to calculate end to end. You can use an application to test throughput requirements without involving disk reads and writes as the reads and writes are executed in memory. Using 1500 byte packets on a gigabit network without testing disk reads and writes should yield about 400-500Mbps of actual throughput

http://63.196.71.246/~phil/jumbo.html

Billy
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