NAME

       btrfs-space-calculator - calculate usable and wasted space

SYNOPSIS

       btrfs-space-calculator [args] sizes

DESCRIPTION

       The btrfs-space-calculator program shows the amount of allocatable space on btrfs physical
       and virtual level, and the amount of unallocatable space resulting from having differently
       sized block devices added to the filesystem.

       In a btrfs filesystem, raw storage is shared by data of different types (System, MetaData
       and Data) and profiles (e.g. single, DUP, RAID1). Also, a filesystem can have multiple
       block devices of different sizes attached.

       An example:

           -$ btrfs-space-calculator -m raid1 -d raid1 2TB 500G 1TB
           Target metadata profile: RAID1
           Target data profile: RAID1
           Mixed block groups: False
           Total raw filesystem size: 3.18TiB
           Device sizes:
             Device 1: 1.82TiB
             Device 2: 465.66GiB
             Device 3: 931.32GiB
           Metadata to data ratio: 1:200
           Estimated virtual space to use for metadata: 7.00GiB
           Estimated virtual space to use for data: 1.36TiB
           Total unallocatable raw amount: 465.66GiB
           Unallocatable raw bytes per device:
             Device 1: 465.66GiB
             Device 2: 0.00B
             Device 3: 0.00B

       Note that most physical disk vendors specify their sizes in GB or TB, while partitions
       created in your average partition table or with lvm2 etc... are usually using MiB, GiB and
       TiB.

OPTIONS

       -h, --help
              Show the built-in help message and exit.

       -m, --metadata PROFILE
              Metadata profile, values like for data profile.

       -d, --data PROFILE
              Data profile, raid0, raid1, raid5, raid6, raid10, dup or single.

       -M, --mixed
              Use mixed block groups (data and metadata profile must match).

       -r, --ratio RATIO
              Data to metadata ratio, e.g. 200 (the default), which means allocate 0.5% for
              metadata. Setting this ratio only makes sense for non-mixed filesystems. When using
              this option in combination with -M, it will be ignored.

SEE ALSO

       This program is an example of what can be done using the python-btrfs library.

       Source and documentation on github: https://github.com/knorrie/python-btrfs

                                               2018                     BTRFS-SPACE-CALCULATOR(1)