RAID USB / Firewire question

[disasterdrone]

I used disk utility to make a raid array (disk spanning) of two 1tb drives into 1 2tb drive to use as a TM backup. One is a firewire 400, the other a USB2.
My question is whether having two interface channels will affect the speed at all. While I know that fw400 is faster than usb2 for sustained transfers, presumably at tm backup will saturate it. Will having the USB interface in addition help? If not, why not? Is there any way to see the utilization of each bus?
Thanks!

 

[Bear]

FW400 is not that much faster than USB 2. All you've really done is make a larger drive that now has more ways it can fail.

 

[disasterdrone]

FW400 is not that much faster than USB 2. All you've really done is make a larger drive that now has more ways it can fail.

Thank you - I realize that there are now two points of failure, but on the plus side, the larger drive is now able to accommodate my TM drive.

My question is about how the two interfaces function. Since half the data is going through the firewire, and half through the usb2 does that mean that I have twice the bandwidth? Or not, and if not, why not?

Thanks!

 

[Bear]

...
My question is about how the two interfaces function. Since half the data is going through the firewire, and half through the usb2 does that mean that I have twice the bandwidth? Or not, and if not, why not?

Thanks!

DId you set it up as a RAID 0/Striped? Or as a Concatenated disk set? If it was RAID 0, you will get more bandwidth pretty much all the time. If it was concatenated, then you only get more bandwidth if you happen to be accessing 2 files simultaneously that are on different disks in the set.

 

[disasterdrone]

DId you set it up as a RAID 0/Striped? Or as a Concatenated disk set? If it was RAID 0, you will get more bandwidth pretty much all the time. If it was concatenated, then you only get more bandwidth if you happen to be accessing 2 files simultaneously that are on different disks in the set.

It's a concatenated disk set.

I would have thought that, over a period of hours of saturating the drives it would be advantageous to have two interfaces, no?

 

[Bear]

It's a concatenated disk set.

I would have thought that, over a period of hours of saturating the drives it would be advantageous to have two interfaces, no?

Not really for a concatenated disk set as it writes to one disk until it is full then it writes to the other disk.

 

[disasterdrone]

Not really for a concatenated disk set as it writes to one disk until it is full then it writes to the other disk.

Thanks - I didn't realize that - would it work differently if the disk set were striped?