1BTRFS-USAGE-REPORT(1) Btrfs Usage Report BTRFS-USAGE-REPORT(1)
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6 btrfs-usage-report - show a detailed usage report about your btrfs
7 filesystem
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11 btrfs-usage-report [args] mountpoint
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15 The btrfs-usage-report program shows a detailed report about how a
16 btrfs filesystem is using available disk space.
17 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.
21 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.
28 The report will show information about:
30 - 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.
35 - 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.
42 - 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.
47 - 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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58 -h, --help
59 Show the built-in help message and exit.
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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.
66 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.
71 Source and documentation on github: https://github.com/knorrie/python-
73 btrfs
74 2018 BTRFS-USAGE-REPORT(1)