Central storage
Central storage is defined to LPs before LP activation. When an LP is activated, storage resources are allocated in contiguous blocks. These allocations can be dynamically reconfigured. Sharing of allocated central storage among multiple LPs is not allowed.
Granularity of initial and reserved central storage amounts is dependent on the largest central storage amount (LCSA) for the LP as follows:
| Largest Central Storage Amount | Storage Granularity |
|---|---|
| LCSA ≤ 512 GB | 1 GB |
| 512 GB < LCSA ≤ 1024 GB | 2 GB |
| 1024 GB < LCSA ≤ 2048 GB | 4 GB |
| 2048 GB < LCSA ≤ 4096 GB | 8 GB |
| 4096 GB < LCSA ≤ 8192 GB | 16 GB |
| 8192 GB <LCSA ≤ 16384 GB | 32 GB |
| 16384 GB <LCSA ≤ 32768 GB | 64 GB |
| 32768 GB <LCSA ≤ 65536 GB | 128 GB |
In support of 2 GB large pages, all logical partition origins and limits must be on a 2 GB boundary. In other words, the addressing range assigned to the LP will start and end on a 2 GB (2048MB) boundary.
The granularity from Table 1 applies across the central input fields (Initial and Reserved fields). Use the larger of the initial and reserved central storage amounts to calculate storage granularity. For example, for an LP with an initial storage amount of 1280 GB and a reserved storage amount of 2848 GB, the central storage granularity of initial and reserved central storage fields is 8 GB, using the larger reserved storage amount to determine storage granularity. The granularity of the central storage origin is not determined from Table 1; the initial storage origin input field granularity is fixed at 2 GB (or 2048 MB).
Additionally, when migrating to these models, you must convert the existing central storage amounts that are not in multiples of the storage granularity supported.
For example, an LP with an initial central storage size of 10368 MB on a previous model with 16 GB of storage installed would require conversion of the initial central storage size to a multiple of 1024 MB (64 MB granularity was valid on this prior model configuration).
Check your central storage definitions and consult your system programmer to ensure that they meet your processing needs.
Use the Customize/Delete Activation Profiles task available to open a reset or image profile to define the central storage for an LP. The Initial, Storage Origin, and Reserved fields are located on the Storage page for the LP. See Figure 1 for an example.