Use the FC Slower Copy2 option to give priority to host I/O response over background copy processing of Compatible FlashCopy® relationships.
When this option is enabled, the maximum number of Compatible FlashCopy® relationships that can be copied simultaneously in the background is reduced to 25% compared to when the option is not specified, thus improving the host I/O response time.
The FC Slower Copy1 and FC Slower Copy2 options perform the same basic function. The difference is that the FC Slower Copy2 option provides the best host I/O response because it suppresses more background copy operations than the FC Slower Copy1 option. When the FC Slower Copy2 option is enabled, the FC Slower Copy1 option is invalid.
When Compatible FlashCopy® background copy operations are suppressed by the FC Slower Copy2 option, the time required for background copying increases. Background copy operation time vary depending on the relationships, so the FC Slower Copy2 option will not necessarily quadruple the time compared to when the option is not specified.
If ShadowImage pairs exist in the same parity group as Compatible FlashCopy® volumes, the host I/O response time might not improve.