[Linux-cluster] Reduced performance question

[Raz Ben-Jehuda(caro)]

i have been measuring the performance of my cluster.
It is compsed of 4 machines, each machine exports 1 sata disk (maxtor
maxline III),
and theses machines are connected 1 Gbps ethernel drive.

Peformance :
I am getting about 40% decrease in performance when i simply read a file.

1. Would switching to infiniband make it faster ?

2. What is GNBD IO model ?

    2.1  Does it use async io ?
          multithreaded IO ?
          sync IO ?

     2.2 When a GNBD servs a node , does it know what is amount of data it
needs
          to fetch right from the start ?
          Meaning , if a node asks for 1MB buffer, would GNBD read 1 MB
buffer
          or several small chunks ?

Thanks
--
Raz
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