Bcache Input Plugin

This plugin gathers statistics for the block layer cache from the stats_total directory and dirty_data file.

⭐ Telegraf v0.2.0 🏷️ system 💻 linux

Global configuration options <!-- @/docs/includes/plugin_config.md -->

Plugins support additional global and plugin configuration settings for tasks such as modifying metrics, tags, and fields, creating aliases, and configuring plugin ordering. See CONFIGURATION.md for more details.

Configuration

# Read metrics of bcache from stats_total and dirty_data
# This plugin ONLY supports Linux
[[inputs.bcache]]
  ## Bcache sets path
  ## If not specified, then default is:
  bcachePath = "/sys/fs/bcache"

  ## By default, Telegraf gather stats for all bcache devices
  ## Setting devices will restrict the stats to the specified
  ## bcache devices.
  bcacheDevs = ["bcache0"]

Metrics

Tags:

• backing_dev device backed by the cache
• bcache_dev device used for caching

Fields:

• dirty_data: Amount of dirty data for this backing device in the cache. Continuously updated unlike the cache set's version, but may be slightly off
• bypassed: Amount of IO (both reads and writes) that has bypassed the cache
• cache_bypass_hits: Hits for IO that is intended to skip the cache
• cache_bypass_misses: Misses for IO that is intended to skip the cache
• cache_hits: Hits per individual IO as seen by bcache sees them; a partial hit is counted as a miss.
• cache_misses: Misses per individual IO as seen by bcache sees them; a partial hit is counted as a miss.
• cache_hit_ratio: Hit to miss ratio
• cache_miss_collisions: Instances where data was going to be inserted into cache from a miss, but raced with a write and data was already present (usually zero since the synchronization for cache misses was rewritten)
• cache_readaheads: Count of times readahead occurred.

Example Output

bcache,backing_dev="md10",bcache_dev="bcache0" dirty_data=11639194i,bypassed=5167704440832i,cache_bypass_hits=146270986i,cache_bypass_misses=0i,cache_hit_ratio=90i,cache_hits=511941651i,cache_miss_collisions=157678i,cache_misses=50647396i,cache_readaheads=0i