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ABCs of z/OS System Programming Volume 3 - IBM Redbooks

ABCs of z/OS System Programming Volume 3 - IBM Redbooks

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3.19 Final capacity increase for volume<br />

Figure 3-19 Capacity increase for volume<br />

Final volume cylinder increase<br />

Since 75,000 cylinders was specified on the panel shown in Figure 3-18 on page 81, the<br />

message displayed in Figure 3-19 is issued when you click OK.<br />

Specify Continue in Figure 3-19, and a requested size <strong>of</strong> 75,684 is processed for the<br />

expansion <strong>of</strong> the volume.<br />

Note: Remember that the number <strong>of</strong> cylinders must be as stated earlier. The reason an<br />

MCU value is 21 cylinders is because it is derived from being the smallest unit that can<br />

map out the largest possible EAV and stay within the index architecture (with a block size<br />

<strong>of</strong> 8192 bytes). It is also a value that divides evenly into the 1 GB storage segments <strong>of</strong> a<br />

DS8000. These 1 GB segments are the allocation unit in the DS8000 and are equivalent to<br />

1113 cylinders. Data sets allocated in cylinder-managed space may have their requested<br />

space quantity rounded up to the next MCU.<br />

82 <strong>ABCs</strong> <strong>of</strong> z/<strong>OS</strong> <strong>System</strong> <strong>Programming</strong> <strong>Volume</strong> 3

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