With the new release of PS Firmware Revision 5.1, Dell introduced more advanced data management options. At the core are 3 load balancing layers that ensure high-performance while balancing capacity value. This post describes the 3 layers and how they can be applied.
EqualLogic Load Balancers in PS Series Pools
When you initialize the first array and create a PS series group, a default pool is automatically established. After adding an array to the group, it is referred to as a member of the group. All members are initially placed into the default pool, and administrators subsequently deploy volumes from this pool. It is within a pool that resources such as network bandwidth, disk capacity, and I/O are balanced automatically. Multiple pools can be created to isolate volumes and separate members. This may be done for a variety of reasons, including technical (e.g. placing specific application data on resources such as SSD) or business reasons (e.g. ensuring that legal department data is isolated from the data from other departments.) With more than one pool administrators can initiate moving volumes or members between the pools seamlessly, with no downtime to the applications. Within a pool, Dell’s EqualLogic PS Series is designed to automate the placement of data to maximize the utilization of the resources that the customer has chosen for their SAN.
There are three load balancers that operate within a pool:
- The NLB (Network Load Balancer) manages the assignment of individual iSCSI connections to Ethernet ports on the pool members
- The CLB (Capacity Load Balancer) manages the utilization of the disk capacity in the pool
- The APLB (Automatic Performance Load Balancer) manages the distribution of high I/O data within the pool.
How the Network Load Balancer (NLB) Works