Based on IBM benchmarks, the throughput for each On-Chip Compression unit is 12 GBps,  which equates to 48 GBps per drawer or 240 GBps for a fully populated five-drawer z15. On-Chip Compression provides an up to 5% improvement in compression ratios for  BSAM/VSAM datasets over zEDC while maintaining full compatibility. Eliminating adapter sharing by using Nest Compression Accelerator  Compression modes z15 migration considerations All z/OS configuration stay the same Consider fail-over and DR sizing Sharing of zEDC cards is limited to 15 LPAR guests per adaptor. The Nest Compression  Accelerator removes this virtualization constraint because it is shared by all PUs on the  processor chip and therefore is available to all LPARs and guests. Moving the compression function from the (PCIe) I/O drawer to the processor chip means that  compression can operate directly in L3 cache and data does not need to be passed by using  I/O operations.  Compression is run in one of the following modes: Note:  The zEDC Express feature does  not  carry forward to z15. The IBM Integrated Accelerator for zEDC is fully compatible with zEDC. Data compressed by  zEDC can be read by z15 (the on-chip) nest accelerator unit and vice versa. No changes are required when moving from earlier systems using zEDC to z15. The IFAPRDxx feature is still required for authorized services. For problem state services,  such as zlib usage of Java, it is not required. The order of magnitude throughput increase on z15 means that the throughput requirements  need to be considered whether failing over to earlier systems with zEDC. GLYPH<SM590000> Synchronous GLYPH<SM590000> Asynchronous Execution occurs in problem state where the user application starts the instruction in its  virtual address space. Execution is optimized for Large Operations under z/OS for authorized applications (for  example, BSAM) and issues I/O by using EADMF for asynchronous execution.  This type of execution maintains the current user experience and provides a transparent  implementation for authorized users of zEDC. Appendix C. IBM Integrated Accelerator for zEnterprise Data Compression  505