Data transmission between HDDs, can someone explain?

[HiSoC8Y]

Ok,

 

So here is my build, My711

 

https://lime-technology.com/forum/index.php?topic=21470.0

 

I'm using LSI MegaRAID card with an Intel RAID Twenty-four port Expander Card RES2SV240.

 

disks 1-4 are connected via one port directly to the LSI MegaRAID card.

disks 5-8 are connected via one port directly to the Intel expander card.

disks 9-12 are connected via one port directly to the Intel expander card.

disks 13-16 are connected via one port directly to the Intel expander card.

disks 17-20 are connected via one port directly to the Intel expander card.

disks 21-24 are connected via one port directly to the Intel expander card.

 

and the two cards are connected via a port on each.

 

When I transfer large amount of data from disk 3 to disk 10 for example, can someone explain the data transmission?

 

What about if I transfer data between two disks that are using the same port connection (e.g. disk18 to disk19)? Will it be faster?

 

I need to identify the bottlenecks in the above tasks.

[c3]

It's all read from the source, into system memory and then written to target (and parity which means more reads to memory). Hence the recommendation for ECC.