RIO-G

I/O Enclosure

 

 

I/O Enclosure

HA HADA HAHA DA

 

 

HAHADA HAHA DA

 

 

 

Server0

pair

 

 

 

Server1

enclosure

 

 

Switches

 

 

 

 

Storage

 

 

 

 

 

 

Switched loop 1

Switched loop 2

 

Figure 5-2 Physical layer as the base for virtualization

Figure 5-2shows the physical layer on which virtualization is based.

Compare this with the ESS design, where there was a real loop and having an 8-pack close to a device adapter was an advantage. This is no longer relevant for the DS8000. Because of the switching design, each drive is in close reach of the device adapter, apart from a few more hops through the Fibre Channel switches for some drives. So, it is not really a loop, but

aswitched FC-AL loop with the FC-AL addressing schema: Arbitrated Loop Physical Addressing (AL-PA).

5.3.1Array sites

An array site is a group of eight DDMs. What DDMs make up an array site is pre-determined by the DS8000, but note, that there is no pre-determined server affinity for array sites. The DDMs selected for an array site are chosen from two disk enclosures on different loops (see Figure 5-3 on page 87).

The DDMs in the array site are of the same DDM type, which means the same capacity and the same speed (RPM).

86DS8000 Series: Concepts and Architecture

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Image 108
IBM DS8000 manual Array sites, Physical layer as the base for virtualization