IBM DS8882F, Introduction And Planning Manual

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When you create a pair of pools, you can choose to automatically assign all
available arrays to the pools, or assign them manually afterward. If the arrays are
assigned automatically, the system balances them across both pools so that the
workload is distributed evenly across both nodes. Automatic assignment also
ensures that spares and device adapter (DA) pairs are distributed equally between
the pools.
If you are connecting to a IBM Z host, you must create a logical subsystem (LSS)
before you can create CKD volumes.
You can create a set of volumes that share characteristics, such as capacity and
storage type, in a pool pair. The system automatically balances the volumes
between both pools. If the pools are managed by Easy Tier, the capacity in the
volumes is automatically distributed among the arrays. If the pools are not
managed by Easy Tier, you can choose to use the rotate capacity allocation method,
which stripes capacity across the arrays.
If the volumes are connecting to a IBM Z host, the next steps of the configuration
process are completed on the host.
If the volumes are connecting to an open systems host, map the volumes to the
host, add host ports to the host, and then map the ports to the I/O ports on the
storage system.
FB volumes can only accept I/O from the host ports of hosts that are mapped to
the volumes. Host ports are zoned to communicate only with certain I/O ports on
the storage system. Zoning is configured either within the storage system by using
I/O port masking, or on the switch. Zoning ensures that the workload is spread
properly over I/O ports and that certain workloads are isolated from one another,
so that they do not interfere with each other.
The workload enters the storage system through I/O ports, which are on the host
adapters. The workload is then fed into the processor nodes, where it can be
cached for faster read/write access. If the workload is not cached, it is stored on
the arrays in the storage enclosures.
Logical configuration with DS CLI
Before you configure your storage system with the DS CLI, it is important to
understand IBM terminology for storage concepts and the storage hierarchy.
In the storage hierarchy, you begin with a physical disk. Logical groupings of eight
disks form an array site. Logical groupings of one array site form an array. After
you define your array storage type as CKD or fixed block, you can create a rank. A
rank is divided into a number of fixed-size extents. If you work with an
open-systems host, a large extent is 1 GiB, and a small extent is 16 MiB. If you
work in an IBM Z environment, a large extent is the size of an IBM 3390 Mod 1
disk drive (1113 cylinders), and a small extent is 21 cylinders.
After you create ranks, your physical storage can be considered virtualized.
Virtualization dissociates your physical storage configuration from your logical
configuration, so that volume sizes are no longer constrained by the physical size
of your arrays.
Chapter 1. Overview
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