Slow Transfer between WD6401AALS & WD1002FAEX

Hi I have 3 WD1002FAEX set as raid 5 and 2 WD6401AALS as raid 0.

When I do a drive test on them (using hdd tach) the average read rate is raid 0= 223 MB/S and the raid 5=127mb/s.

The problem I have is when I transfer files from the raid 0 to my storage drive raid 5 it starts off at 200mb/s and slowly makes its way down to a sustained  23mb/s.

Could this problem be due to the interfaces being different ie 3gb/s to 6gb/s?

The raid 5 is set as GUID format and the raid 0 as MBR format, could this cause the problem?

Note: I was running the caviar greens in raid 5 before i replaced them with the caviar black 1tb and it would sustain 80mb/s tranfers with the greens.

Thankyou. any help is much appriciated.

Just for reference:

WD1002FAEX = 1tb, 64mb cache, 6gb/s sata, caviar black.

WD6401AALS= 640mb, 32mb cache, 3gb/s sata, caviar black 

My system:

i7 @ 4ghz

asus rampage ii extreme

6gb ram

2x 4870x2

hardware or software raid?

perhaps bad cable(s)?

The raid driver i’m using is the one built on the mb (intel matrix).

Replaced the cables but problem still there.

Fix the problem.

Had to go into the intel matrix and enable cache write back. 

Now transfer at 123mb/s :slight_smile: