IBM TotalStorage DS6000 Series - Manual (Page 163)

Chapter 8. Configuration planning 139
Figure 8-7 Example of connecting several expansion enclosures
8.4.2 Logical configurations
The capacity of the physical disk drives is not equal to the capacity you can use in the
DS6000 series. Among the reasons for this are that the user will configure either RAID-5 or
RAID-10, and the DS6000 series exploits virtualization concepts, which use some of the
available physical capacity. See Chapter 4, “Virtualization concepts” on page 65 for more
details.
The logical capacity depends on not only the capacity of the DDMs but also the RAID type
and the number of spare disks in a rank. We describe the capacity in the following figures.
1
16
1
16
1
16
Expansion
enclosure 1
Device adapter
chipset inside
controller 1
Expansion
enclosure 3
Additional
enclosures to a
maximum of four
per loop
1
16
1
16
1
16
Additional
enclosures to a
maximum of four
per loop
Expansion
enclosure 2
Server Enclosure
FC switch
16 DDMs per
enclosure
4 FC-AL Ports
Loop 0
(accessed via the
disk exp ports)
Loop 1
(accessed via
the disk
contrl ports)
2Gb FC-AL link
Device adapter
chipset inside
controller 2
Attention:
The figures used in this chapter are still subject to change. Specifically, the exact
number of extents per rank may be slightly different.
You might ensure there is at least 5% of additional capacity, if you are providing an
exact number of devices.
– There will also potentially be unusable space for devices which are not an integer
number of extents in size and for the last extent in an extent pool.
– To prepare for unexpected situations, a certain amount of margin is required for
important systems.