HP StorageWorks SAN Virtualization Services Platform Best Practices Guide (5697-0935, May 2011)

5 Storage pools
Construction of storage pools plays a critical role and ultimately affects the performance and
availability of the virtual disks presented to servers in the SVSP environment. This chapter discusses
several factors that need to be considered when building and managing storage pools.
Types of storage pools
Storage Pools are built from LUs that are presented from one or more storage arrays to the SVSP;
these LUs are called back-end LUs. There are two types of storage pools that can be built from the
back-end LUs: a capacity pool and a performance pool. A capacity pool is created by selecting
one or more back-end LUs and adding them to the pool. Data blocks for a virtual disk created from
a capacity pool will be concatenated from the members of the pool. A performance pool is created
by selecting one or more stripe sets and adding them to the pool, with each individual stripe set
being a collection of back-end LUs. Data blocks for a virtual disk created from a performance pool
will be striped across all the back-end LUs that are members of each individual stripe set, but
concatenated from the multiple stripe sets in the pool.
Figure 10 Storage pool creation
Building back-end LUs
The performance and availability of a storage pool is affected by the performance and availability
characteristics of the underlying back-end LUs. The type of array used to build the back-end LUs
can influence those characteristics.
Spreading the back-end LU across a large number of physical disks has the potential for better
performance.
Depending upon the array, the choice of RAID level assigned to the back-end LU may influence
the number of physical disks that can be grouped together. Choose a RAID level that meets
availability needs, but spreads the back-end LU across as many disks as possible. For example,
an HP EVA array spreads the load across all the physical spindles in a given disk group, which
could include all the disks in the array. The EVA VRAID levels, VRAID1 and VRAID5, take advantage
Types of storage pools 23