9.4 Backup and RECOVER  9.4.1 Performance measurements 9.5 Decompression improvement in utilities In Db2 12, the software algorithm improvement during decompression is also enabled for  utilities. This enablement demonstrated noticeable improvement in utilities under zEC12. This  feature is available in V12R1M100. Around the same time, the system z13 processor also  provides better compression performance by using hardware improvement. Because z13  improvement applies for Db2 11 and 12, we observed less improvement in DB12 that used  z13 compared to the case that used zEC12. In Db2 11, decompression improvement was introduced to access rows in a compressed  table space. This feature substantially reduced CPU usage in Db2 11 when many  compressed rows are processed by SQL queries because Db2 partially decompresses only  the necessary data and applies software algorithm. In Db2 11, this feature was limited to SQL  access and not used by utilities. Because of this improvement in the RESTORE phase, RECOVER showed no regression  overall. RECOVER performance of a single table space and a list of partitions of a partitioned table  space showed up to 27% CPU improvement in the RESTORE phase compared to Db2 11.  In Db2 12, RECOVER always uses one parallel task to overlap read and write during the  RESTORE phase, even if the PARALLEL keyword is not specified. This configuration results  in more efficient processing because reading the pages from the image copies and restoring  pages to the buffer pool processes can occur asynchronously.  The use of hardcoded DD statements to pre-allocate the image copy data sets on tape in the  RECOVER job step is no longer supported and causes allocation errors. This feature is available in V12R1M100. Chapter 9. Utilities  295