1BTRFS-USAGE-REPORT(1)         Btrfs Usage Report         BTRFS-USAGE-REPORT(1)
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NAME

6       btrfs-usage-report - show a detailed usage report about your btrfs
7       filesystem
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SYNOPSIS

11       btrfs-usage-report [args] mountpoint
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DESCRIPTION

15       The btrfs-usage-report program shows a detailed report about how a
16       btrfs filesystem is using available disk space.
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18       The filesystem to show information about needs to be online and
19       mounted.  Because the needed information is retrieved using the btrfs
20       kernel API, it has to be run as root.
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22       In a btrfs filesystem, raw storage is shared by data of different types
23       (System, MetaData and Data) and profiles (e.g. single, DUP, RAID1).
24       Also, a filesystem can have multiple block devices of different sizes
25       attached. All of this together confuses regular tools like df, which
26       will already fail to show us how much free space we still have to add
27       more data to the filesystem.
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29       The report will show information about:
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31       - Physical disk space usage. On this level we can see the amount of
32       disk space allocated for specific combinations of type and profile.
33       E.g. 1GiB of Data with profile RAID1 will show that two devices both
34       store 1GiB of raw data, because it is duplicated.
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36       - Virtual disk space usage. The btrfs virtual address space shows the
37       amount of data we store disregarding the storage profile. So, if we
38       store 1GiB of data using a RAID1 profile, then the virtual address
39       space shows we have 1GiB of data, while the physical space usage will
40       show up as 2GiB in total. Note that when using compression, the virtual
41       address space counts compressed data instead of uncompressed data.
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43       - Estimated free virtual space left for use. By extrapolating the
44       current usage patterns, a prediction can be made that shows how much
45       extra data can be added to the filesystem. These are the values that
46       you would like to have df show you.
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48       - Unallocatable disk space, which is raw physical disk space that
49       cannot be used, either because allocations in the filesystem are
50       unbalanced, or because of having different sizes of devices attached.
51       Additionally, it will show us if disk space can be reclaimed for use by
52       using btrfs balance.  When converting between profiles, these values
53       can quickly show you if the conversion to another profile can actually
54       be completed or not.
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OPTIONS

58       -h, --help
59              Show the built-in help message and exit.
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SEE ALSO

63       btrfs-space-calculator is a program that can calculate the amount of
64       allocatable (and unallocatable) disk space based on a list of (maybe
65       differently sized) block devices and target profiles to use.
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67       This program is an example of what can be done using the python-btrfs
68       library.  Do not parse the output of this program, as it just displays
69       data that is readily available when using functionality from this
70       library.
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72       Source and documentation on github: https://github.com/knorrie/python-
73       btrfs
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77                                     2018                BTRFS-USAGE-REPORT(1)
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