[clug] How to connect two Linux boxes? [SEC=UNCLASSIFIED]

[Alex Satrapa]

On 03/09/2009, at 14:08 , <Ross.Wilson at ga.gov.au> wrote:

> This second machine has a running network connection and an unused  
> second network card.

Ubuntu will autoconfigure interfaces when they become connected, I  
don't think RedHat will do that. You'll either need to connect the  
Ubuntu box to the same network, or very carefully bring the unused  
interface on the RedHat box up, and perform a bit of Ethernet magic.

The easiest option is to find a disk bigger than the data set.

To connect the two computers together using the second network card  
you'll need to:
- Find a network that isn't in use, eg: 172.28.0.16
   You can try pinging various numbers in that range to double check
- Bring the interface on the RedHat box up (check with a RedHat geek  
how to do
   this properly/safely)
- Bring the interface on the Ubuntu box up (again, check the Ubuntu  
geeks,
   they'll have the right advice)
- Connect the boxes either using a crossover cable, an Ethernet switch,
   or a straight-through cable if either or both boxes have MDI-X  
Ethernet ports
   (these ports are on all Mac hardware this century) which can auto- 
sense polarity
- Check that each machine can ping the other one

That's the connectivity sorted out. Again, easiest option is to plonk  
the Ubuntu box on the same network as the RedHat box.

If the data is in the form of many files in a specific directory  
structure, use rsync over SSH to copy the data to the Ubuntu box. Then  
as the data set on the RedHat box grows, you will only need to copy  
the changes across but beware that rsync will heavily load the hard  
drive while it does the checksums and the two machines compare notes.

FTP can be faster than rsync over SSH, but doesn't cater for future  
growth of the dataset (unless you really want to track 2TB of data by  
hand). Even faster than FTP would be using netcat to pipe raw data  
over the Ethernet network.

I'd suggest that the bandwidth of a FireWire 800 hard drive array is  
greater than the usable bandwidth of a Gigabit Ethernet network[1].  
Attaching a large hard drive array via FireWire will also result in  
lower CPU usage on both boxes (overheads of FireWire and a file system  
being less than the overheads of Ethernet packet handling, IP protocol  
handling, FTP/SSH handling, and then a file system on top of that  
all). If both machines can support FireWire 800, that's the option I'd  
be looking at (at least for the initial data load).

Alex
[1] http://www.codinghorror.com/blog/archives/000339.html

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