On Tue, Aug 18, 2015 at 6:29 PM, Lennart Poettering <lenn...@poettering.net> wrote: > Why would you not do this?
GNU tar's documentation mentions the main drawback: However, be aware that `--sparse' option presents a serious drawback. Namely, in order to determine if the file is sparse `tar' has to read it before trying to archive it, so in total the file is read *twice*. So, always bear in mind that the time needed to process all files with this option is roughly twice the time needed to archive them without it. I think having to scan a multi-gigabyte file for zeroes before archiving it would slow down the process quite a bit. It doesn't sound like GNU tar supports querying for holes using FIEMAP or something similar. Besides this, I guess it could be a portability issue. libarchive tar's man page contains: There is not yet any support for multi-volume archives or for archiving sparse files. Instead, libarchive supports transforming zero-filled blocks into holes while extracting. It depends on the compression to archive sparse files efficiently. _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
