Defining storage pools

The SAS RAID controller modules support the implementation of RAID 0, RAID 1, RAID 5, and RAID 0+1. Typically, you will define two storage pools.

A storage pool (also called a RAID array) is a collection of disk drives that become a logical entity. When you create a storage pool, you select the desired capacity (number of disk drives) and assign a RAID level to it which will provide a redundancy level.

Storage pools are assigned to a primary SAS RAID controller module when they are created. Defining two or more storage pools, and alternating storage pool ownership between the two SAS RAID controller modules will generally result in better performance.
Note: When defining storage pools using Storage Configuration Manager Web interface, the system will automatically select the primary controller for a new storage pool to maximize balanced performance.
Use the following considerations when planning for storage pools:
  • All hard disk drives in a storage pool must be the same type, and a disk drive can only belong to one storage pool.
    Note: When installing SAS RAID controller modules in a BladeCenter S chassis, you must use SAS hard disk drives. SATA hard disk drives are not supported.
  • When determining which hard disk drives are in a storage pool, you should use hard disk drives from both disk storage modules (if both are installed) to maintain the highest availability. For example, if you are implementing a RAID 1 storage pool, consider using a hard disk drive in one disk storage module and mirroring that drive to a hard disk drive in the other disk storage module.
You can choose from the following RAID implementations when defining storage pools:
Also known as a striped set or a striped volume, a RAID 0 implementation stores data evenly across two or more hard disk drives. No data redundancy is available. To implement RAID 0, you must use at least 2 hard disk drives.

You can implement RAID 0 with hard disk drives of different sizes. However, the storage space added to the storage pool be each disk is limited to the size of the smallest disk. For example, if you implement RAID 0 with a hard disk drive that is 120GB and a hard disk drive that is 100GB, the total size of the storage pool is 200GB.

A RAID 1 implementation creates an exact copy of data (also called mirroring) on two or more hard disk drives. Each hard disk drive in the storage pool contains a complete copy of the data and it can be addressed independently.
A RAID 5 implementation uses block-level striping with parity data distributed across all hard disk drives in the storage pool. You can increase the number of hard disk drives in the storage pool dynamically. To implement RAID 5, you must use at least 3 hard disk drives.
RAID 1+0
A RAID 1+0 implementation combines the function or RAID 0 with the function of RAID 1. Drives are mirrored and data is striped across those drives. To implement RAID 0+1, you must use at least 4 hard disk drives.