Bcache Tuning

  • By Canonical BootStack Charmers
  • Storage
Channel Version Revision Published Runs on
latest/stable da3dfd6 10 28 Apr 2022
Ubuntu 20.04 Ubuntu 18.04 Ubuntu 16.04
latest/candidate a40fccd 11 Today
Ubuntu 22.04 Ubuntu 20.04 Ubuntu 18.04
latest/edge a40fccd 11 16 Aug 2022
Ubuntu 22.04 Ubuntu 20.04 Ubuntu 18.04
juju deploy bcache-tuning
Show information


20.04 18.04 16.04


This charm performs best-practice performance tuning of bcache devices on SD/NVMe based installations.

Cache Set Configuration

Disable performance based congestion behaviour - the SSD or NVMe will in all likelyhood always be faster than the underlying spindle:

congested_read_threshold_us: 0
congested_write_threshold_us: 0

Bcache Backing Device Configuration

Disable cache readahead:

readahead: 0

Disable writethrough of sequential data writes:

sequential_cutoff: 0

Set the amount of dirty data the cache device will hold before starting to persist to the backing device:

writeback_percent: 10

Sets unmanaged cache_mode:

cache_mode: unmanaged


To use this charm, simple deploy and relation to principle services:

juju deploy bcache-tuning
juju add-relation bcache-tuning ceph-osd
juju add-relation bcache-tuning nova-compute

This charm presents no configuration options.