FlashCopy Wizard: Specifying the Capacity for a Repository Logical Drive

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A repository logical drive stores FlashCopy metadata (data about the FlashCopy) and any copy-on-write data needed during the life of the FlashCopy logical drive to maintain an accurate point-in-time image of the base logical drive.

Important: In most situations, the 20% default value should be ample capacity for your repository logical drive.

Use the spinner box to set the desired capacity. The capacity needed will vary, depending on the frequency and size of I/O writes to the base logical drive and how long you need to keep the FlashCopy logical drive. In general you should choose a larger capacity for the repository if you intend to keep the FlashCopy logical drive for a long period of time and/or if a large percentage of data blocks will change on the base logical drive during the life of the FlashCopy logical drive due to heavy I/O activity. Use historical performance monitor data or other operating system utilities to help you determine typical I/O activity to the base logical drive.

Note: The absolute minimum size a repository logical drive can be is 8MB. By default, the size of the repository logical drive defaults to 20% of the base logical drive. If there is not enough free capacity for 20%, it will be set to the highest possible percentage.

If you are not sure how large to make the repository logical drive, accept the default. Remember that you are given a warning when the repository logical drive reaches a certain percentage full, called a threshold level . You can set the threshold level when you create a FlashCopy logical drive using the advanced path, but the default threshold level is 50% on the Simple Path.

If you get a warning and determine that the repository logical drive is in danger of filling up before you are finished with the FlashCopy logical drive, you can increase its capacity using the Logical Drive >> Increase Capacity option. If the repository logical drive fills up before you are finished with the FlashCopy, the repository logical drive full conditions specify what action that will be taken.

Related Topics

Creating a FlashCopy Logical Drive Using the FlashCopy Logical Drive Wizard

Managing Logical Drives