26 Implementing the IBM Storwize V7000 with IBM Spectrum Virtualize V8.2.1
The front of an Expansion Enclosure is shown in Figure 2-8.
Figure 2-8   Front of IBM Storwize V7000 Expansion Enclosure
Figure 2-9 shows a rear view of an expansion enclosure.
Figure 2-9   Rear of IBM Storwize V7000 expansion enclosure
SAS chain limitations
When attaching expansion enclosures to the control enclosure, you are not limited by type of 
the enclosure (if it meets all generation level restrictions). The only limitation for each SAS 
chain is its chain weight. Each type of enclosure defined its own chain weight:
/SM590000Enclosures 12F and 24F have a chain weight of 1
/SM590000Enclosure 92F has a chain weight of 2.5
The maximum chain weight is 10. 
For example, you can combine seven 24F and one 92F expansions (7x1 + 1x2.5 = 9.5 chain 
weight), or two 92F enclosures, one 12F, and four 24F (2x2.5 + 1x1 + 4x1 = 10 chain weight).