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Hitachi Lightning 9900™ V Series LUN Expansion and Virtual LVI/LUN User’s Guide 9
1.2.2 Virtual LVI/LUN Size Calculation
The Virtual LVI/LUN Remote Console function enables you to configure LDEVs by dividing
them into several devices. Virtual LVI/LUN allows you to assign a specific number of physical
cylinders or MB to each Virtual LVI/LUN volume for maximum control over the volume size.
For S/390
®
, each Virtual LVI volume contains the user-specified number of user cylinders
plus a predetermined number of control cylinders, which is calculated as follows:
# Physical Tracks = (# User Cylinders) × 15 + (# Control Cylinders) × 15 + Adjustment
Tracks
1 Cylinder = 15 Tracks
Where:
# Control Cylinders =4, 5, 6, 7, 8, 9, 25, or 27, depending on LVI type
(see Table 1.5)
Adjustment Tracks
(( # User Cylinders ) + ( # Control Cylinders ))
× 15 ×48
48
-(( # User Cylinders ) + ( # Control Cylinders )) × 15
(↑↑ means round up to the next integer, e.g. ↑ 3.96 ↑ = 4.00)
For example, if you specify 1015 user cylinders for a 3390-3 Virtual LVI volume, the total
number of physical cylinders allocated for that device is 1015
× 15 + 6 × 15 + 45 = 15360
tracks (1024 cylinders).
In open systems, the size of the Virtual LUN volume is expressed in MB. The total size of the
Virtual LUN volume consists of the user-specified size plus an amount for the control area
(see Table 1.5). The amount for the control area is automatically assigned by the Virtual
LVI/LUN software. The size calculation is as follows:
X = User specified MB × 1024 ÷ 720 (Any remainder is rounded up to the next whole number).
Y=(X× 96 × 15 × 512) ÷ 1024 ÷ 1024
X is a value of converting the capacity specified by user into number of cylinders.
Y is a value of converting value X into capacity (MB).
For example, if an open-systems user specifies a Virtual LUN volume size of 100 MB, the
software will calculate the actual size of the volume as follows: 100 × 1024 ÷ 720 = 142.2222
(rounded up to 143). (143
× 96 × 15 × 512) ÷ 1024 ÷ 1024 = 100.546875 (MB).