When preparing a backup fails due to apparent corruption on a data page, there is not much information in the output. Running a debug build with --dbug=d,ib_log is often unpractical due to the slowness of the debug build.

Let us implement a new option --verbose, which will display information about redo log application during mariabackup --prepare, like this:

Applying log to page 0:49
apply 1646941: MLOG_4BYTES len 4 page 0:49
apply 1647127: MLOG_4BYTES len 4 page 0:49
apply 1647134: MLOG_2BYTES len 3 page 0:49
apply 1647140: MLOG_4BYTES len 4 page 0:49
apply 1647147: MLOG_2BYTES len 3 page 0:49
apply 1647189: MLOG_4BYTES len 3 page 0:49