A storage pool is a combination of LUNs. In a small volume it might consist of a single RAID array, but storage pools in many volumes consist of multiple arrays.
Xsan distributes file data in parallel across the LUNs in a storage pool using a RAID 0 (striping) scheme. So, you can improve a clients access speed by distributing available storage over several LUNs in a storage pool.
Within each storage pool in a volume, Xsan stripes file
data across the individual LUNs that make up the storage pool. Once again, performance is improved because data is written in parallel. You can tune SAN performance by adjusting the amount of data written to each LUN in a storage pool (the stripe breadth) to suit a critical application.