Maxtor DiamondMax 10: Exploring NCQ & RAID
The Impact of Stripe Sizes (Cont.)
 |
|
Stripe size seems to have almost no impact on seek time for either configuration. And once again, the higher rotational speed of the Raptor drives makes them the performance leader.
Here we start to see the price of the smaller stripe size. When a 1MB file is broken in hundreds of pieces rather than dozens, it requires more CPU power to disassemble/reassemble all the parts.
In RAID 5, the opposite pattern is true. The larger stripe sizes result in fewer data slices, which means means fewer parity calculations. In RAID 5, the two larger sizes are almost identical in performance where the smallest stripe size (16K for RAID 5 rather then the 4K available in RAID 0), is slower. In any case, the dismal write performance must be a serious consideration.
Stripe Size Performance Summary:
There is no hard and fast rule about stripe sizes and RAID performance. Additionally, the usage of the array is as critical as the components that make it up. In general, RAID 5 should only be used where system survivability through a drive failure is critical or on systems where write performance is not significant.
