[G4] EIDE and Ultra ATA RAID

[Ralph Garrett]

On Apr 25, 2005, at 6:02 PM, Kevin Willis wrote:

>   Was the improvement due to the RAID, or clean drives?  Wouldn't a 
> striped RAID at the very least kinda double your hard drives cache 
> size?  Since the CPU is handling the same amount of data, but the 
> drive is only having to handle half of the data?
>

Probably due to both. HD's don't operate as fast when they are almost 
full. That's due to the fact that the data is stored from the outside 
in and the head speed relative to the disk (data rate) drops as it 
moves closer to the spindle.

High end RAID Arrays usually have software to control how much data is 
stored to prevent performance drop offs caused by disks being filled to 
capacity. Another way to do it is to partition several drives and only 
use the first (outer) partitions in the Array.

As Phil pointed out, a lot of how a RAID performs depends on the 
hardware/software controllers used to setup the Array.

Ralph