Internal Disk Configuration Granularity - IBM Multiprise 3000 Reference Manual

Control Unit Logical Address
Each of the three enclosures of a fully populated Multiprise 3000 contains a disk
subsystem with a logical 3990 mod 2 control unit.
Device Address (on the logical control unit)
Each array is assigned a fixed, contiguous range of device addresses. The number
of device addresses for a 4+P array is 64 and for a 6+P array it is 96. The three
possible arrays in a CPC frame are assigned the device addresses as follows:
The three possible arrays in an expansion frame are assigned the device
addresses as follows:

Internal Disk Configuration Granularity

The Internal Disk subsystem may consist of as little as one CPC frame containing
one RAID array, and as much as the CPC frame plus two expansion frames with a
total of nine RAID arrays in the three frames.
Growth of a configuration within a frame is straight forward. The entry CEC frame
has one RAID array. Arrays may be added, one at a time, up to the maximum in
the frame of 3 RAID arrays. One SSA loop on a SSA adapter card manages all of
the HDDs within the CPC frame. The SSA adapter card is capable of supporting
two SSA loops, so one of the loops is unused in the single frame configuration.
Similarly, the expansion frames may contain 1, 2, or 3 RAID arrays. The supported
configurations in the CPC frame:
Table 1-4. Configurations in CPC Frame
Number
B1
B2
B3
When the first expansion frame is added, another SSA adapter card is also added.
If a second expansion frame is added, the SSA adapter card in the CPC frame
services the HDD enclosure in that frame.
1-10
Internal Disk Subsystem Reference Guide
The logical control unit that controls the HDD enclosure in the CPC frame is
assigned control unit logical address x'0'.
The logical control unit that controls the HDD enclosure in the first expansion
frame is assigned control unit logical address x'1'.
The logical control unit that controls the HDD enclosure in the second
expansion frame is assigned control unit logical address x'2'.
First array, 4+P, addresses 0 to 63 (x'00' to x'3F).
Second array, 4+P, addresses 64 to 127 (x'40' to x'7F').
Third array, 4+P, addresses 128 to 191 (x'80' to x'BF').
First array, 4+P, addresses 0 to 63 (x'00' to x'3F').
Second array, 6+P, addresses 64 to 159 (x'40' to x'9F').
Third array, 6+P, addresses 160 to 255 (x'A0' to x'FF').
Configuration
4+P, Spare
4+P, 4+P, Spare
4+P, 4+P, 4+P, Spare
Approximate Gross Disk Capacity
(GByte)
4 * 18 = 72
8 * 18 = 144
12 * 18 = 216