FlexScale increases the performance of the storage system by reducing disk reads. With FlexScale's Performance Accelerator Module and its WAFL extended cache, your storage system's cache memory can hold up to 127 aggregates (which would mean 127 traditional volumes, if your system uses only traditional volumes). As long as you have fewer than 127 aggregates total, there is no limit to the number of flexible volumes that can be cached by the WAFL extended cache.
If more than 127 aggregates exist on a system with extended cache, only the first 127 aggregates with buffers added to WAFL extended cache are cached.