IBM DS8000 manual DDM to DA Mapping -- 2-way

DDM to DA Mapping -- 2-way

2

disk enclosure pair

(32 DDMs can be installed

2 means to attach to DA pair 2)

0/1

I/O drawer

(0/1 means device adapters for DA pair 0 and 1)

S0

Server

(0 means server 0)

disk enclosure pair installation sequence

2

2

0

0

S0

S1

0/1 1/0

2/3 3/2

Base Frame

3

3

1

1

2

2

0

0

Expansion Frame

Figure 9-13 DDM to DA mapping (2-way model)

Model 921 can have four DA pairs and 12 disk enclosure pairs (1 disk enclosure pair can have 16 x 2 =32 DDMs). And each two disk enclosure pairs (64 DDMs) is connected to a DA pair in order.

For example, the first 64 DDMs are connected to the DA pair 2, the next 64 DDMs are connected to the DA pair 0, and so on. Therefore, a 256 DDMs configuration is a well-balanced configuration (all four DA pairs have 64 DDMs).

If you install more than 256 DDMs in the DS8100, the next disk enclosures are connected to the DA pair 2 again. When you have the maximum DDMs (384 DDMs), DA pair 0 and 1 have 128 DDMs and DA pair 2 and 3 have 64 DDMs.

Figure 9-14 on page 183 shows the DS8300 Model 922 (4-way model).

182DS8000 Series: Concepts and Architecture