IBM TotalStorage DS6000 Series - Manual (Page 177)

Chapter 9. The DS Storage Manager: Logical configuration 153
Figure 9-1 Diagram of hosts and host attachment groups
In Figure 9-1 we 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.
However, multiple host attachments, even different open system host types, with the
same blocksize 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 9-3 on page 157.
For FICON attachment, access is controlled by zSeries HCD/IOGEN definitions. Some
FICON attachment considerations:
– One storage subsystem FICON host definition will be required as the trigger to set the
I/O adapter that will be accessed by the FICON protocol.
– Default volume groups are automatically created, allowing anonymous access for
FICON.
One set of host definitions may be used for multiple storage, storage units, and storage
complexes.
pSeries1
pSeries2
pSeries3
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
One host attachment group defined
for host pSeries3
Fiber Channel
Port
W
W
PN
1
W
W
PN
2
W
W
PN
3
W
W
PN
4
W
W
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5
W
W
PN
6
W
W
PN
7
W
W
PN
8
W
W
PN
9
W
W
PN
10
W
W
PN
11
W
W
PN
12