Planning Storage Pools

When planning your storage pool configuration, you will want to place volumes in the pool that provides the appropriate capacity and level of performance and service. You may need to prioritize applications, determine how you want to segregate them, and ensure you have sufficient capacity in each pool.

To create a successful storage configuration, identify the following:

• Capacity and performance of each member. You should consider the following factors:
• Disk type, either Serial Attached SCSI (SAS) or Serial Advanced Technology Attachment (SATA)
• Disk size
• Disk speed
• Member RAID level

Within a pool, it is recommended that members with the same disk spin rate have the same RAID level. For example, if a pool contains two members that have 7200 RPM disks installed, both members should be configured with the same RAID level.

• Disk space and performance needs of each application. You should determine which applications deserve priority and identify their disk space and network bandwidth needs and performance characteristics. For example, some applications perform many random data transfers, while others perform a small number of large sequential data transfers. In addition, you should determine which volumes do not require the highest performance, such as rarely-accessed volumes that are used only to archive data.
• How the pools will be organized. Identify the number of pools and which members will be assigned to each pool, based on the member performance characteristics and capacities and the requirements of the volumes. For example, you may want to organize your pools according to disk speed. You could also organize pools according to member RAID level.
• Application volumes that will be assigned to each pool. Volumes with the highest service level needs should be assigned to a pool that meets those needs. The volumes used by an application can be assigned to different pools, as needed.

When assigning volumes to pools, the RAID level of the pool members may be important. For a workload characterized by many small random transfers, RAID 10 may provide the highest throughput, while a workload characterized by many large sequential transfers may perform equally well with either RAID 10 or RAID 50. If you do not know the optimal RAID level for a volume, be sure that the pool to which the volume is assigned contains members with a variety of RAID levels, so automatic performance load balancing can occur.

You should consider future demands for capacity and performance when planning the storage pool configuration.

In addition, monitor the group and applications to ensure that the storage configuration provides adequate service levels across various workloads.

As needed, you can move members and volumes from one pool to another—with no impact on availability or performance. For example, if the capacity of a pool is not sufficient, you can either add a new member to the pool or move an existing member to the pool.

For more information on using pools, see the related Technical Report, available on the Technical Support website.