A single transactionally consistent backup file?

[Ron Johnson]

On the systems I've used up until now (legacy OpenVMS for almost 20 years, and MSSQL), multi-file database backups have been to a single, transactionally consistent "stand alone" file suitable for copying to tape, or even written directly to tape.  They're always smaller than the original database files, even when compression is not enabled.

When I run innobackupex and innobackupex --apply-log, though, I get a set of files and directories that's almost a direct copy of the source datadir.

This would mean that a 750GB database would require 1500GB for two full backups, plus more for incrementals, and 20% more for free space on the volume.  (That doesn't come cheap in enterprise shops, especially when you start adding in duplicate DR sites, etc, etc.)

Am I missing something fundamental, or is that how MySQL/Percona expects backups to work?

Thanks.