Storage Statistics

Storage Statistics

$ benji storage-stats --help
usage: benji storage-stats [-h] [storage_name]

positional arguments:
  storage_name  Storage

optional arguments:
  -h, --help    show this help message and exit

This command outputs the number of objects and their space usage. It will take some time as it enumerates all objects in the storage.

Space Usage Statistics

$ benji storage-usage --help
usage: benji storage-usage [-h] [filter_expression]

positional arguments:
  filter_expression  Version filter expression

optional arguments:
  -h, --help         show this help message and exit

This command provides space usage statistics over all or a subset of versions:

INFO: $ /home/lf/src/backy2/venv/bin/benji storage-usage
| storage   | virtual | sparse | shared | exclusive | deduplicated_exclusive |
| storage-1 | 12.7MiB | 1.0MiB |   0.0B |   11.7MiB |                 6.2MiB |

Answering the question of how much space a number of versions occupy on the storages is inherently hard to do due to the storage-wide deduplication that Benji employs. But this command tries to answer this question at least in part. If called without any arguments the statistics are calculated over all versions. But in general a filter expression should be used to limit the number of versions. Calculating these statistics is an expensive operation and will take some time if the number of versions and blocks is large.

  • virtual: This number is the sum of the sizes of all matching versions. It is virtual in the sense that it does not represent the actual space usage on the storage.

  • sparse: This is the number of bytes that are sparse. Sparse blocks do not take up any space.

  • shared: This value represents the number of bytes that the matched subset of versions shares with other versions which are not part of this set.

  • exclusive: These are the number of bytes that are exclusive to this subset. If a block is used more than once in this subset of versions then it is counted multiple times towards this figure.

  • deduplicated_exclusive: This is like exclusive but only counts each distinct block on the storage once. It is an estimate of the space that would be freed if all matching versions would be deleted.

  • The sum of sparse, shared and exclusive equals virtual.