[SOLVED]Slow copy disk to disk

Hello, first at all i'm a french guy so don't be too hard with my english

Here is my problem.

Actually i run a omv 0.5 server. debian 6 kernel 3.2
My server is a i3 3.2 with 4 gb ram
i have a ssd for my system
and 4 WD caviar green 2tb and 1 WB RED 3tb

till 3 day ago everything goes right but for now when i want to move something
like a movie between two disk my tranfers rate never goes up then 10mb/s.

Last week the speed was around 80mb/s and i change nothing to my server.

i try to change sata cables. power supply and i reinstall everything but no change. i reset my CM configuration also.

i try this command

root@Skynet:~# hdparm -tT /dev/sda


/dev/sda:
 Timing cached reads:   11418 MB in  2.00 seconds = 5713.24 MB/sec
 Timing buffered disk reads: 296 MB in  3.02 seconds =  98.15 MB/sec


root@Skynet:~# hdparm -tT /dev/sdb


/dev/sdb:
 Timing cached reads:   10290 MB in  2.00 seconds = 5149.69 MB/sec
 Timing buffered disk reads: 470 MB in  3.00 seconds = 156.49 MB/sec

At this moment i have no other idea for fix this.

Pls help me

I'm full of shame. 3 day ago i move my server and i put the rj45 in a old switch, so when i move my file from disk A to disk B under my sweetdumb windows my tranfers rate drop to 10mb/s.

I don't understand why windows copy this file in temp or anywhere but the probleme was that indeed.

Sorry for the trouble and thank u for your responce

And long live to OMV