Compressed backups work only with backup sets, not imagecopies.
压缩的备份只对备份集有效，对映像副本无效。
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For example, if a tester manually validates a particular text for a particular image, then he can program a machine to validate the same text for copies of the image throughout the application.
DB2 starts at the last backup image that contains complete copies of all table Spaces you are restoring, and then applies subsequent incremental images.