EAV significantly increases the addressable disk storage and provides constraint relief for z/OS environments that are approaching the four-digit device number limit.
EAV increases the amount of addressable DASD storage per volume beyond 65,520 cylinders by changing how tracks are addressed. This increase is accomplished with a new track address format within the Volume Table of Contents (VTOC), which is referred to as 28-bit cylinder track address and a new way to manage this extra space as multicylinder units.
The following EAV increases are available for recent z/OS releases:
- For z/OS 1.12, the largest supported EAV volume is 262,668 cylinders
- For z/OS 1.13, the largest supported EAV volume is 1,182,006 cylinders
With EAV, IBM implements an architecture that provides capacities of hundreds of terabytes (TB) for a single volume.