IBM Midrange System DS4000 Series Hardware Manual page 118

Note: The usable disk space is less than the overall disk capacity. Consider these usable
capacity amounts for storage capacity calculation issues:
73.4 GB formatted capacity is equal to 67.85 GB usable capacity.
146.8 GB formatted capacity is equal to 136.21 GB usable capacity.
300 GB formatted capacity is equal to 278.88 GB usable capacity.
450 GB formatted capacity is equal to 415.58 GB usable capacity.
600 GB formatted capacity is equal to 558.28 GB usable capacity.
750 GB formatted capacity is equal to 697.98 GB usable capacity.
1000 GB formatted capacity is equal to 930.81 GB usable capacity.
The usable capacities are what the SMclient will report as storage that can be used by the
hosts. We arrive at this number through the following steps:
1. Take the listed raw disk amount (listed in decimal, per the storage industry standard),
multiply by 1000
1,000,000,000 bytes. 1 binary GB = 1,073,741,824 bytes (2
2. Subtract the 512 MB configuration database, that is, the DACstore (the region that
holds controllers and configuration information) after converting to binary.
This gives you the usable binary capacity that can be utilized by hosts and is what the
SMclient will report to you as usable capacity.
Front view
The front of the subsystem provides access to the sixteen portable canister contained drives.
There are three summary LEDs at the bottom of the front panel, as shown in Figure 3-72:
White: Locate (number 3)
This White Locator LED aids in module identification.
Amber: Summary Fault (number 4)
When there is a fault condition, this LED glows amber.
Green: Power (number 5)
This LED glows green when at least one power supply is operational.
Figure 3-72 EXP5000 and EXP520 front panel
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IBM Midrange System Storage Hardware Guide
3, 3
and divide by 1024 to get a raw binary capacity (1 decimal GB =
30
bytes)).