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StorageTek SL3000 Systems Assurance Guide E20876-08 |
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# 4 Capacity

There are two types of capacity:

- Physical Capacity — the number of data cartridge slots in the library (which excludes reserved slots for cleaning cartridges, diagnostic cartridges, and the module identification block).

- Active Capacity — the number of slots in the library that have been activated by an activation permit file. Only these active storage slots can be used for data storage and accessed by a client. Inactivated slots are not recognized by the library.

Physical storage capacity can range from 205 to 5,925 data cartridge slots depending on library configuration. The capacity of a module in the library depends on its position relative to other modules and the features selected for the module. The features that affect capacity include: additional drive arrays, CAPs, operator panels, and window arrays.

When determining the required storage capacity, it is suggested to plan for future expansion. Although modules can be added to an SL3000 library at any time, adding a module is disruptive to library operations. Therefore, Oracle recommends adding physical capacity in advance to meet future storage needs. With additional physical capacity pre-installed, increasing library capacity only involves purchasing and downloading an activation file. Activating additional capacity is non-disruptive to library operations.

A diagram of the slot locations within each module can be helpful to understanding capacity. For wall maps that show the individual slot locations in the library, refer to the SL3000 User's Guide.

## Physical Capacity

The features selected and the position of a module affect the capacity of the library. Use the table below to calculate the physical capacity of an SL3000 library. Each module type is listed in the table, followed by the options that can be selected for that module.

To calculate the slot capacity, start with the standard configuration slot count. Then, either add or subtract slots from the standard slot count to reflect the options selected and position of the module in the library. Finally, add the slot counts of each module together to get the total slot count for the library.

Note: For additional drive arrays, if a base module or DEM has a module to the left, subtract the "Adjacent Module Left" value and the "Standard" value. For example, a Base with two drive arrays and a module to the left would subtract 66 slots from the standard capacity.

A library can be configured with a maximum of eight CEMs and two AEMs or six CEMs and two PEMs. PEMs and AEMs must be placed at the ends of the library. A single AEM may be installed in a library to support bulk loading, but it is recommended that a single AEM be placed on the left-side of centerline to maximize library capacity. Two AEMs support bulk loading and dual robotics.

Table 4-1 Physical Slot Capacity Per Module

Physical Configuration | AEM | PEM | CEM | DEM | Base | CEM | PEM | AEM
--- | --- | --- | --- | --- | --- | --- | --- | ---
Standard | 0 | 308 | 516 | 410 | 320 | 620 | 312 | 0
2nd Drive Array (Adjacent Module Left/Standard) | -- | -- | -- | -11/-55 | -11/-55 | -- | -- | --
3rd Drive Array (Adjacent Module Left/Standard) | -- | -- | -- | -12/-60 | -12/-60 | -- | -- | --
4th Drive Array (Adjacent Module Left/Standard) | -- | -- | -- | -13/-65 | -- | -- | -- | --
Adjacent Module to Left | -- | -- | +104 | +88 | +88 | 0 | 0 | --
Adjacent Module to Right | -- | 0 | 0 | 0 | +13 | 0 | -- | --
CAP | -- | -78 | -78 | -77 | Std. | -78 | -- | --
Window Storage Array | -- | -- | -- | +23 | +23 | -- | -- | --

### Calculating Physical Capacity Examples

This section provides example calculations of the total physical capacity for three library configurations.

#### Example 1: Base, DEM, CEMs, PEMs

The sample library in the figure below has a base module, a DEM, two CEMs (one on each side of CenterLine), and two PEMs (one on each end of library).

Figure 4-1 Physical Capacity Example with Base, DEM, CEMs, PEMs

The capacity of each module and the library total capacity is described below:

- Base module with operator's panel, a module installed on the right and on the left, and three total drive arrays:

  320(standard) + 0(op panel) + 13(right module) + 88(left module) – 66(2nd drive array) – 72(3rd drive array) = 283

- DEM, a module installed on the left, window array, a CAP, and four drive arrays:

  410(standard) + 88(left module) + 23(window array) – 77(CAP) – 66(2nd drive array) – 72(3rd drive array) – 78(4th drive array) = 228

- CEM installed to the left of CenterLine and a module installed on the left:

  516(standard) + 104(left module) = 620

- CEM installed to the right of CenterLine, a module installed on right, and a CAP:

  516(standard) + 104(left module) – 78(CAP) = 542

- PEMs (always installed in pairs), one with a CAP, one without:

  308(left of center) + 312(right of center) – 78(CAP) = 542

- The library TOTAL capacity would be:

  283(base) + 228(DEM) + 620(left CEM) + 542(right CEM) + 542(PEMs) = 2,215

#### Example 2: Base and CEM

The sample library in the figure below has a base module and a CEM to the right of center line.

Figure 4-2 Physical Capacity Example with Base and CEM

The capacity of each module and the library total capacity is described below:

- Base module with a window array, a module installed on the right, and three total drive arrays:

  320(standard) + 13(right module) + 23(window array) – 55(2nd drive array) – 60(3rd drive array) = 241

- CEM installed to the right of CenterLine, and a CAP:

  516(standard) + 104(left module) – 78(CAP) = 542

- The library TOTAL capacity would be:

  241(base) + 542(right CEM) = 783

#### Example 3: Base, DEM, CEMs, AEM

The sample library in the figure below has a base module, DEM, two CEMs, and a single AEM for bulk loading

Figure 4-3 Physical Capacity Example with Base, DEM, CEMs, AEM

Note: It is not recommended to install a single AEM on the right, as shown in the figure above. If the AEM was installed on the left end of the library, 104 additional cartridge slots would be accessible in the far left CEM.

The capacity of each module and the library total capacity is described below:

- Base module with a window array, a module installed on the right and on the left, and two total drive arrays:

  320(standard) + 23(window array) + 13(right module) + 88(left module) – 66(2nd drive array) = 378

- DEM, a module installed on the left, op panel, and three drive arrays:

  410(standard) + 88(left module) + 0(op panel) – 66(2nd drive array) – 72(3rd drive array) = 360

- CEM installed to the left of CenterLine:

  516(standard) = 516

- CEM installed to the right of CenterLine, a module installed on right:

  516(standard) + 104(left module) = 542

- AEM installed to right of CenterLine (not recommended for single AEM):

  0(standard) = 0

- The library TOTAL capacity would be:

  378(base) + 360(DEM) + 516(left CEM) + 620(right CEM) + 0(AEM) = 1,874

## Active Capacity

The capacity for the SL3000 library uses Capacity on Demand and RealTime Growth to allow customers to instantly increase and activate capacity without disruption.

### RealTime Growth

RealTime Growth allows physical capacity to be pre-installed and then activated as needed. Additional library modules are installed during the initial install. Then, through Capacity on Demand, the customer pays to activate slots when additional capacity become necessary. No additional physical library components are required.

### Capacity on Demand

Capacity on Demand is non-disruptive, allowing the customer to increase capacity within the library by activating previously installed, yet inactive slots. The SL3000 library offers capacity slot upgrades in 25, 100, 200, 500, and 1000 slot increments. To activate a capacity upgrade, a hardware activation file is required (see "Hardware Activation Files").

#### Non-disruptive Capacity and Partitioning Changes

Changes to active capacity result in minimal disruptions to library operations. With HLI libraries, an increase in active capacity doesn't stop host jobs or cause host connections to go offline. When the capacity changes, the library is offline only momentarily and automatically comes back online.

The specific library behavior depends on the type of host connection, HLI or FC-SCSI. For details, refer to the SL3000 User's Guide.

Note: Although changes to active capacity are non-disruptive to current library hosts, it is recommended that you make the library unavailable to other user requests before committing the active storage region changes.