Put external array on 2nd 6402 channel or separate 642 controller?

[CA1411553]

I have a DL380 G3 with a Smart Array 6402/128 controller running 6 internal U320 hard drives. I have an external disk array with a U3 interface.

Would it be best to connect the external array to the second channel of my existing 6402 or install my spare SA642 and connect the external array to that?

Obviously the SA 6402 is a better controller but I'm wondering if the performance for my external array would be better on a separate, but less capable, controller.

Thanks for any comments!

[Chris Rosan]

You should use the seperate card. I take it the drives in the chassis of the DL380 are U320? if you connect a U3 device to the same card then the ENTIRE card and ALL devices will only perform at U3 (160Mbps) rather than U320 (320mbps).

I would be putting it on the SA642. It may have less RAM/cache but it's the better option than slowing your existing array down.

[Kedd Guyton]

Chris, isn't the SA-6402 capable of running U320 on one channel and U3 (U160) on the other channel?

[CA1411553]

The SA6402 is capable of running individual hard drives at U320 speeds even if some drives in the same ARRAY are only U3.

In this case, the internal channel is running at U320 even with the external channel running at U3; I checked.

I'm just wondering if the 6402 is so much better than the 642 that it can handle the external channel better than the 642 even with the internal channel running on it.

[Chris Rosan]

Then that's contradicts what i've been told.

I don't think that the performance of the 6402 will be that much greater than the 642, especially as you only have the std ram. It would depend if you are copying a lot of data between raid array's (such as disk to disk backup).

Suggest you try it on both cards and see which performs best for your situation.