IBM DS8000 manual PSeries1 PSeries2

Fiber Channel Port

pSeries1

W

P N

1

P N

2

P

N

3

P

N

4

W

W

W

W

W

W

W

pSeries2

P

N

5

N

6

P N

7

P

N

8

W

P

W

W

W

W W

W

W

NO Host Attachment Group defined for host pSeries1. By default,

the 4 ports are placed in 4 Host Attachments

Two Host Attachment Groups defined for host pSeries2

pSeries3

W

P

N 9

P N

1

0

P

N

11

P

N

12

W

W

W

W

W

W

W

One Host Attachment Group defined for host pSeries3

Figure 10-1 Diagram of hosts and host attachment groups

￿In Figure 10-1we show three pSeries hosts with four host ports each. The first host, pSeries1, has no specific attachment groupings, so each port could be defined as an attachment. Server ports can be grouped in attachments for convenience. For example, pSeries2 shows two host attachments, with two ports in each attachment. Server pSeries3 shows one host attachment with four ports grouped in the one attachment.

￿A host attachment can be configured to access specific disk subsystem I/O ports or all valid disk subsystem I/O ports.

￿Host attachments can be configured to access specific volume groups.

￿A specific host attachment (one port or set of grouped ports) can access only one volume group.

￿Multiple host attachments, even different open system host types, with the same block size and addressing mode, can access the same volume group. The safest approach to this concept is to configure one host per volume group. If shared access to the LUN is required, for example, for dual pathing or clustering, then the shared LUNs may be placed in multiple volume groups as shown in Figure 10-3 on page 195.

￿FICON/ESCON attachment access is controlled by zSeries HCD/IOGEN definitions. Some ESCON/FICON attachment considerations follow.

–One storage subsystem FICON host definition will be needed in order to configure I/O adapters to use FICON protocol instead of FCP protocol.

–No storage subsystem host definition will be required for ESCON hosts since ESCON adapters are single purpose and do not require configuration.

–Default volume groups are automatically created, allowing anonymous access for

ESCON/FICON.

Chapter 10. The DS Storage Manager - logical configuration 191