What effect does RAID stripe size have on read-ahead settings?
- by stbrody
I'm trying to figure out the correct read-ahead values to set on a RAID10 array, and I'm wondering if the RAID stripe size should factor into my considerations.
I've heard conflicting information about this in the past. I once heard that you should always set your read-ahead value to a multiple of the RAID stripe size, and never below the stripe size, because that is the minimum amount of data the RAID controller will ever try to read at once.
Someone else told me, however, that setting read-ahead below the stripe size is fine, and can, in fact, increase the amount of parallel reads you can do across devices in the array, increasing performance and decreasing load on the array.
So which is it? Do read-ahead settings that aren't multiples of the stripe size make sense or not?
