From 0977cb31846c11f54f3db9039b8761ccf9e21615 Mon Sep 17 00:00:00 2001 From: Axel Burri Date: Fri, 2 Aug 2019 21:45:27 +0200 Subject: [PATCH] documentation: btrbk.1: add action "extents-diff" (flagged as experimental) --- doc/btrbk.1.asciidoc | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/doc/btrbk.1.asciidoc b/doc/btrbk.1.asciidoc index 61c89f4..c57f9c6 100644 --- a/doc/btrbk.1.asciidoc +++ b/doc/btrbk.1.asciidoc @@ -365,6 +365,30 @@ different output formats. *diff* :: Print new files since subvolume for subvolume . +*extents-diff* ... [exclusive ...] _*experimental*_:: + List estimated size and diff from extent information (FIEMAP ioctl) + from filefrag(8). The 'diff' column shows the data added (relative + complement of block regions) from the 'subvol' of the previous + line. In the best case (if no other files hold references to the + extents in question) the 'diff' data would be freed when deleting + the subvolume. ++ +If called with the 'exclusive' keyword, subvolumes matching '' +are added to a separate set, and the exclusive data is computed for +this set. This gives a hint of how much data will be freed if deleting +all subvolumes in the set. Example: + + btrbk extents-diff /backup/data.* exclusive /backup/data.2010* + ++ +If called with the '--related' option, btrbk also lists all related +subvolumes. This is not recommended for backups, as parent-uuid +relations break for received subvolumes as soon as an intermediate +subvolume is deleted. ++ +Note that reading all extents is a disk-intensive task, expect long +execution times and high ram usage. Consider setting 'cache_dir'. + *ls* |...:: List all btrfs subvolumes below . Use the '--format' command line option to switch between different output formats.