Using Storage Pools to Separate SAN Storage

Storage consolidation through a SAN allows many applications and workloads to use a single pool of storage. Well-designed SANs can improve storage utilization, increase reliability, and dramatically simplify storage management.

While storage consolidation makes it easier to manage, provision, and back up data, it can limit your ability to meet other business objectives. For example, environments with conflicting or competing storage requirements may need more flexibility in allocating SAN resources—while still maintaining a single-system view of the storage.

To meet the need for flexible and efficient storage, you can divide PS Series group space into multiple storage pools. Using "SAN within a SAN" technology, administrators can easily segregate workloads, while retaining the advantages of storage consolidation.

For example, you can separate storage by application, service level, disk type, cost, location, or department. You can assign mission critical applications to their own storage hardware resources—ensuring fast and consistent performance—and assign disaster recovery replicas, backups, and archived data to different resources.

In order to separate storage space in a PS Series group, you need multiple members. You can create up to four storage pools in a group and assign each member to a pool.

If a pool has sufficient space, you can assign volumes to the pool. Only the resources provided by the pool members are available to the volumes.

For example, Figure 1: One-Member, Single-Pool Group shows a single-member group with one pool (the default pool). Volume data is automatically balanced across the member disks.

Figure 1: One-Member, Single-Pool Group

When you add a member to a group, you can assign the new member to the default pool, or you can create another pool and assign the member to the new pool. Volumes can then be assigned to the new pool.

For example, Figure 2: Three-Member, Single-Pool Group shows a three-member, single-pool group. Volume data is automatically balanced across the pool members. In addition, performance load balancing will attempt to place volume data on pool members with the RAID level that is optimal for the application, as determined by internal group metrics.

Figure 2: Three-Member, Single-Pool Group

To separate storage in a multi-member group, you must create additional pools and assign members and volumes to the pools. Only the storage space and network resources provided by the pool members are available to the volumes assigned to the pool. As usual, automatic performance and capacity balancing takes place—but only among the pool members.

Figure 3: Three Member, Two-Pool Group shows a three-member, two-pool group.

Figure 3: Three Member, Two-Pool Group

Members and volumes can be assigned only to one pool at a time. As capacity needs change, you can move members and volumes from one pool to another. When a member is moved to a different pool, all volume data on the member must be moved to the remaining pool members. Therefore, the remaining pool members must have enough space to store the volume data.

When moving members and volumes between pools, data movement occurs online, enabling administrators to easily optimize business objectives without downtime or after-hours maintenance, thus improving storage utilization and service levels.