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A Standby CoD disk set contains 16 disk drives of the same capacity and RPM (10000 or 15000 RPM). With this offering, up to four Standby CoD disk drive sets (64 disk drives) can be factory or field installed into your system.

To activate, you logically configure the disk drives for use. This is a non-disruptive activity that does not require intervention from IBM. Upon activation of any portion of the Standby CoD disk drive set, you must place an order with IBM to initiate billing for the activated set. At that time, you can also order replacement Standby CoD disk drive sets.

For more details, refer to the IBM TotalStorage DS8000 Introduction and Planning Guide, GC35-0495.

9.4.5 Capacity and well-balanced configuration

The DDMs are installed in the DS8000 according to a rule of installation sequence of disk enclosures. Sometimes, the installation rule is related to the arrangement of your data. The installation rule is defined as follows:

￿Each disk enclosure can contain 16 DDMs or dummy carriers, and a pair of disk enclosures (32 DDMs) is installed in the DS8000 at the same time.

￿Each disk enclosure is connected to a specific DA pair, and two disk enclosure pairs (64 DDMs) are connected to a DA pair sequentially.

For example, if you install 96 DDMs in a DS8000, the first two disk enclosure pairs (64 DDMs) are connected to the DA pair 0, and next one disk enclosure pair (32 DDM) is connected to the DA pair 1.

The following figures illustrate the installation rule of the disk enclosures.

Figure 9-13 on page 182 shows a DS8100 Model 921 (2-way model).

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