IBM TotalStorage DS300 Best Practices Manual page 192

Figure 4-154 Array with Flashcopy source and target logical drive - Changed data on
target logical drive
As more data is changed in the time of an backup or by writing on the target
logical drive as more free space in the array is required to increase the size of the
target logical drive. The target logical drive can grow up to the same size as the
source logical drive. When there is not enough space for the increase of the
target logical drive is available than becomes the Flashcopy invalid and must be
deleted.
Multiple Flashcopys can be created from a single logical drive. The Flashcopys
will build a Flashcopy group. The COW Lookup table and the COW data area
shared between Flashcopys of the same Flashcopy group. Every Flashcopy
group requires 2MB system memory. The firmware allows up to 4 Flashcopys per
enclosure. When more Flashcopys are required, a feature key must be
purchased to upgrade the possible four Flashcopys to 256. Depending on the
usage, more system memory is also required. IBM offers a system memory
upgrade to 1GB for the TotalStorage DS400 and the TotalStorage DS300 model
1701-1RS and 1701-2RD.
Note: With the TotalStorage DS300 1701-1RL, only 4 Flashcopys can be
used. The system memory upgrade and the Flashcopy upgrade to 256
Flashcopys are not supported.
To create Flashcopy or SnapShot from a logical drive perform the following steps:
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IBM TotalStorage DS300 and DS400 Best Practices Guide