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README.md

ZFS plugin

This ZFS plugin provides metrics from your ZFS filesystems. It supports ZFS on Linux and FreeBSD. It gets ZFS stat from /proc/spl/kstat/zfs on Linux and from sysctl and zpool on FreeBSD.

Configuration:

[[inputs.zfs]]
  ## ZFS kstat path. Ignored on FreeBSD
  ## If not specified, then default is:
  # kstatPath = "/proc/spl/kstat/zfs"

  ## By default, telegraf gather all zfs stats
  ## Override the stats list using the kstatMetrics array:
  ## For FreeBSD, the default is:
  # kstatMetrics = ["arcstats", "zfetchstats", "vdev_cache_stats"]
  ## For Linux, the default is:
  # kstatMetrics = ["abdstats", "arcstats", "dnodestats", "dbufcachestats",
  #     "dmu_tx", "fm", "vdev_mirror_stats", "zfetchstats", "zil"]

  ## By default, don't gather zpool stats
  # poolMetrics = false

Measurements & Fields:

By default this plugin collects metrics about ZFS internals and pool. These metrics are either counters or measure sizes in bytes. These metrics will be in the zfs measurement with the field names listed bellow.

If poolMetrics is enabled then additional metrics will be gathered for each pool.

  • zfs With fields listed bellow.

ARC Stats (FreeBSD and Linux)

  • arcstats_allocated (FreeBSD only)
  • arcstats_anon_evict_data (Linux only)
  • arcstats_anon_evict_metadata (Linux only)
  • arcstats_anon_evictable_data (FreeBSD only)
  • arcstats_anon_evictable_metadata (FreeBSD only)
  • arcstats_anon_size
  • arcstats_arc_loaned_bytes (Linux only)
  • arcstats_arc_meta_limit
  • arcstats_arc_meta_max
  • arcstats_arc_meta_min (FreeBSD only)
  • arcstats_arc_meta_used
  • arcstats_arc_no_grow (Linux only)
  • arcstats_arc_prune (Linux only)
  • arcstats_arc_tempreserve (Linux only)
  • arcstats_c
  • arcstats_c_max
  • arcstats_c_min
  • arcstats_data_size
  • arcstats_deleted
  • arcstats_demand_data_hits
  • arcstats_demand_data_misses
  • arcstats_demand_hit_predictive_prefetch (FreeBSD only)
  • arcstats_demand_metadata_hits
  • arcstats_demand_metadata_misses
  • arcstats_duplicate_buffers
  • arcstats_duplicate_buffers_size
  • arcstats_duplicate_reads
  • arcstats_evict_l2_cached
  • arcstats_evict_l2_eligible
  • arcstats_evict_l2_ineligible
  • arcstats_evict_l2_skip (FreeBSD only)
  • arcstats_evict_not_enough (FreeBSD only)
  • arcstats_evict_skip
  • arcstats_hash_chain_max
  • arcstats_hash_chains
  • arcstats_hash_collisions
  • arcstats_hash_elements
  • arcstats_hash_elements_max
  • arcstats_hdr_size
  • arcstats_hits
  • arcstats_l2_abort_lowmem
  • arcstats_l2_asize
  • arcstats_l2_cdata_free_on_write
  • arcstats_l2_cksum_bad
  • arcstats_l2_compress_failures
  • arcstats_l2_compress_successes
  • arcstats_l2_compress_zeros
  • arcstats_l2_evict_l1cached (FreeBSD only)
  • arcstats_l2_evict_lock_retry
  • arcstats_l2_evict_reading
  • arcstats_l2_feeds
  • arcstats_l2_free_on_write
  • arcstats_l2_hdr_size
  • arcstats_l2_hits
  • arcstats_l2_io_error
  • arcstats_l2_misses
  • arcstats_l2_read_bytes
  • arcstats_l2_rw_clash
  • arcstats_l2_size
  • arcstats_l2_write_buffer_bytes_scanned (FreeBSD only)
  • arcstats_l2_write_buffer_iter (FreeBSD only)
  • arcstats_l2_write_buffer_list_iter (FreeBSD only)
  • arcstats_l2_write_buffer_list_null_iter (FreeBSD only)
  • arcstats_l2_write_bytes
  • arcstats_l2_write_full (FreeBSD only)
  • arcstats_l2_write_in_l2 (FreeBSD only)
  • arcstats_l2_write_io_in_progress (FreeBSD only)
  • arcstats_l2_write_not_cacheable (FreeBSD only)
  • arcstats_l2_write_passed_headroom (FreeBSD only)
  • arcstats_l2_write_pios (FreeBSD only)
  • arcstats_l2_write_spa_mismatch (FreeBSD only)
  • arcstats_l2_write_trylock_fail (FreeBSD only)
  • arcstats_l2_writes_done
  • arcstats_l2_writes_error
  • arcstats_l2_writes_hdr_miss (Linux only)
  • arcstats_l2_writes_lock_retry (FreeBSD only)
  • arcstats_l2_writes_sent
  • arcstats_memory_direct_count (Linux only)
  • arcstats_memory_indirect_count (Linux only)
  • arcstats_memory_throttle_count
  • arcstats_meta_size (Linux only)
  • arcstats_mfu_evict_data (Linux only)
  • arcstats_mfu_evict_metadata (Linux only)
  • arcstats_mfu_ghost_evict_data (Linux only)
  • arcstats_mfu_ghost_evict_metadata (Linux only)
  • arcstats_metadata_size (FreeBSD only)
  • arcstats_mfu_evictable_data (FreeBSD only)
  • arcstats_mfu_evictable_metadata (FreeBSD only)
  • arcstats_mfu_ghost_evictable_data (FreeBSD only)
  • arcstats_mfu_ghost_evictable_metadata (FreeBSD only)
  • arcstats_mfu_ghost_hits
  • arcstats_mfu_ghost_size
  • arcstats_mfu_hits
  • arcstats_mfu_size
  • arcstats_misses
  • arcstats_mru_evict_data (Linux only)
  • arcstats_mru_evict_metadata (Linux only)
  • arcstats_mru_ghost_evict_data (Linux only)
  • arcstats_mru_ghost_evict_metadata (Linux only)
  • arcstats_mru_evictable_data (FreeBSD only)
  • arcstats_mru_evictable_metadata (FreeBSD only)
  • arcstats_mru_ghost_evictable_data (FreeBSD only)
  • arcstats_mru_ghost_evictable_metadata (FreeBSD only)
  • arcstats_mru_ghost_hits
  • arcstats_mru_ghost_size
  • arcstats_mru_hits
  • arcstats_mru_size
  • arcstats_mutex_miss
  • arcstats_other_size
  • arcstats_p
  • arcstats_prefetch_data_hits
  • arcstats_prefetch_data_misses
  • arcstats_prefetch_metadata_hits
  • arcstats_prefetch_metadata_misses
  • arcstats_recycle_miss (Linux only)
  • arcstats_size
  • arcstats_sync_wait_for_async (FreeBSD only)

Zfetch Stats (FreeBSD and Linux)

  • zfetchstats_bogus_streams (Linux only)
  • zfetchstats_colinear_hits (Linux only)
  • zfetchstats_colinear_misses (Linux only)
  • zfetchstats_hits
  • zfetchstats_max_streams (FreeBSD only)
  • zfetchstats_misses
  • zfetchstats_reclaim_failures (Linux only)
  • zfetchstats_reclaim_successes (Linux only)
  • zfetchstats_streams_noresets (Linux only)
  • zfetchstats_streams_resets (Linux only)
  • zfetchstats_stride_hits (Linux only)
  • zfetchstats_stride_misses (Linux only)

Vdev Cache Stats (FreeBSD)

  • vdev_cache_stats_delegations
  • vdev_cache_stats_hits
  • vdev_cache_stats_misses

Pool Metrics (optional)

On Linux (reference: kstat accumulated time and queue length statistics):

  • zfs_pool
    • nread (integer, bytes)
    • nwritten (integer, bytes)
    • reads (integer, count)
    • writes (integer, count)
    • wtime (integer, nanoseconds)
    • wlentime (integer, queuelength * nanoseconds)
    • wupdate (integer, timestamp)
    • rtime (integer, nanoseconds)
    • rlentime (integer, queuelength * nanoseconds)
    • rupdate (integer, timestamp)
    • wcnt (integer, count)
    • rcnt (integer, count)

On FreeBSD:

  • zfs_pool
    • allocated (integer, bytes)
    • capacity (integer, bytes)
    • dedupratio (float, ratio)
    • free (integer, bytes)
    • size (integer, bytes)
    • fragmentation (integer, percent)

Tags:

  • ZFS stats (zfs) will have the following tag:

    • pools - A :: concatenated list of all ZFS pools on the machine.
  • Pool metrics (zfs_pool) will have the following tag:

    • pool - with the name of the pool which the metrics are for.
    • health - the health status of the pool. (FreeBSD only)

Example Output:

$ ./telegraf --config telegraf.conf --input-filter zfs --test
* Plugin: zfs, Collection 1
> zfs_pool,health=ONLINE,pool=zroot allocated=1578590208i,capacity=2i,dedupratio=1,fragmentation=1i,free=64456531968i,size=66035122176i 1464473103625653908
> zfs,pools=zroot arcstats_allocated=4167764i,arcstats_anon_evictable_data=0i,arcstats_anon_evictable_metadata=0i,arcstats_anon_size=16896i,arcstats_arc_meta_limit=10485760i,arcstats_arc_meta_max=115269568i,arcstats_arc_meta_min=8388608i,arcstats_arc_meta_used=51977456i,arcstats_c=16777216i,arcstats_c_max=41943040i,arcstats_c_min=16777216i,arcstats_data_size=0i,arcstats_deleted=1699340i,arcstats_demand_data_hits=14836131i,arcstats_demand_data_misses=2842945i,arcstats_demand_hit_predictive_prefetch=0i,arcstats_demand_metadata_hits=1655006i,arcstats_demand_metadata_misses=830074i,arcstats_duplicate_buffers=0i,arcstats_duplicate_buffers_size=0i,arcstats_duplicate_reads=123i,arcstats_evict_l2_cached=0i,arcstats_evict_l2_eligible=332172623872i,arcstats_evict_l2_ineligible=6168576i,arcstats_evict_l2_skip=0i,arcstats_evict_not_enough=12189444i,arcstats_evict_skip=195190764i,arcstats_hash_chain_max=2i,arcstats_hash_chains=10i,arcstats_hash_collisions=43134i,arcstats_hash_elements=2268i,arcstats_hash_elements_max=6136i,arcstats_hdr_size=565632i,arcstats_hits=16515778i,arcstats_l2_abort_lowmem=0i,arcstats_l2_asize=0i,arcstats_l2_cdata_free_on_write=0i,arcstats_l2_cksum_bad=0i,arcstats_l2_compress_failures=0i,arcstats_l2_compress_successes=0i,arcstats_l2_compress_zeros=0i,arcstats_l2_evict_l1cached=0i,arcstats_l2_evict_lock_retry=0i,arcstats_l2_evict_reading=0i,arcstats_l2_feeds=0i,arcstats_l2_free_on_write=0i,arcstats_l2_hdr_size=0i,arcstats_l2_hits=0i,arcstats_l2_io_error=0i,arcstats_l2_misses=0i,arcstats_l2_read_bytes=0i,arcstats_l2_rw_clash=0i,arcstats_l2_size=0i,arcstats_l2_write_buffer_bytes_scanned=0i,arcstats_l2_write_buffer_iter=0i,arcstats_l2_write_buffer_list_iter=0i,arcstats_l2_write_buffer_list_null_iter=0i,arcstats_l2_write_bytes=0i,arcstats_l2_write_full=0i,arcstats_l2_write_in_l2=0i,arcstats_l2_write_io_in_progress=0i,arcstats_l2_write_not_cacheable=380i,arcstats_l2_write_passed_headroom=0i,arcstats_l2_write_pios=0i,arcstats_l2_write_spa_mismatch=0i,arcstats_l2_write_trylock_fail=0i,arcstats_l2_writes_done=0i,arcstats_l2_writes_error=0i,arcstats_l2_writes_lock_retry=0i,arcstats_l2_writes_sent=0i,arcstats_memory_throttle_count=0i,arcstats_metadata_size=17014784i,arcstats_mfu_evictable_data=0i,arcstats_mfu_evictable_metadata=16384i,arcstats_mfu_ghost_evictable_data=5723648i,arcstats_mfu_ghost_evictable_metadata=10709504i,arcstats_mfu_ghost_hits=1315619i,arcstats_mfu_ghost_size=16433152i,arcstats_mfu_hits=7646611i,arcstats_mfu_size=305152i,arcstats_misses=3676993i,arcstats_mru_evictable_data=0i,arcstats_mru_evictable_metadata=0i,arcstats_mru_ghost_evictable_data=0i,arcstats_mru_ghost_evictable_metadata=80896i,arcstats_mru_ghost_hits=324250i,arcstats_mru_ghost_size=80896i,arcstats_mru_hits=8844526i,arcstats_mru_size=16693248i,arcstats_mutex_miss=354023i,arcstats_other_size=34397040i,arcstats_p=4172800i,arcstats_prefetch_data_hits=0i,arcstats_prefetch_data_misses=0i,arcstats_prefetch_metadata_hits=24641i,arcstats_prefetch_metadata_misses=3974i,arcstats_size=51977456i,arcstats_sync_wait_for_async=0i,vdev_cache_stats_delegations=779i,vdev_cache_stats_hits=323123i,vdev_cache_stats_misses=59929i,zfetchstats_hits=0i,zfetchstats_max_streams=0i,zfetchstats_misses=0i 1464473103634124908

Description

A short description for some of the metrics.

ARC Stats

arcstats_hits Total amount of cache hits in the arc.

arcstats_misses Total amount of cache misses in the arc.

arcstats_demand_data_hits Amount of cache hits for demand data, this is what matters (is good) for your application/share.

arcstats_demand_data_misses Amount of cache misses for demand data, this is what matters (is bad) for your application/share.

arcstats_demand_metadata_hits Amount of cache hits for demand metadata, this matters (is good) for getting filesystem data (ls,find,…)

arcstats_demand_metadata_misses Amount of cache misses for demand metadata, this matters (is bad) for getting filesystem data (ls,find,…)

arcstats_prefetch_data_hits The zfs prefetcher tried to prefetch something, but it was already cached (boring)

arcstats_prefetch_data_misses The zfs prefetcher prefetched something which was not in the cache (good job, could become a demand hit in the future)

arcstats_prefetch_metadata_hits Same as above, but for metadata

arcstats_prefetch_metadata_misses Same as above, but for metadata

arcstats_mru_hits Cache hit in the “most recently used cache”, we move this to the mfu cache.

arcstats_mru_ghost_hits Cache hit in the “most recently used ghost list” we had this item in the cache, but evicted it, maybe we should increase the mru cache size.

arcstats_mfu_hits Cache hit in the “most frequently used cache” we move this to the beginning of the mfu cache.

arcstats_mfu_ghost_hits Cache hit in the “most frequently used ghost list” we had this item in the cache, but evicted it, maybe we should increase the mfu cache size.

arcstats_allocated New data is written to the cache.

arcstats_deleted Old data is evicted (deleted) from the cache.

arcstats_evict_l2_cached We evicted something from the arc, but its still cached in the l2 if we need it.

arcstats_evict_l2_eligible We evicted something from the arc, and it’s not in the l2 this is sad. (maybe we hadn’t had enough time to store it there)

arcstats_evict_l2_ineligible We evicted something which cannot be stored in the l2. Reasons could be:

  • We have multiple pools, we evicted something from a pool whithout an l2 device.
  • The zfs property secondary cache.

arcstats_c Arc target size, this is the size the system thinks the arc should have.

arcstats_size Total size of the arc.

arcstats_l2_hits Hits to the L2 cache. (It was not in the arc, but in the l2 cache)

arcstats_l2_misses Miss to the L2 cache. (It was not in the arc, and not in the l2 cache)

arcstats_l2_size Size of the l2 cache.

arcstats_l2_hdr_size Size of the metadata in the arc (ram) used to manage (lookup if something is in the l2) the l2 cache.

Zfetch Stats

zfetchstats_hits Counts the number of cache hits, to items which are in the cache because of the prefetcher.

zfetchstats_misses Counts the number of prefetch cache misses.

zfetchstats_colinear_hits Counts the number of cache hits, to items which are in the cache because of the prefetcher (prefetched linear reads)

zfetchstats_stride_hits Counts the number of cache hits, to items which are in the cache because of the prefetcher (prefetched stride reads)

Vdev Cache Stats (FreeBSD only)

note: the vdev cache is deprecated in some ZFS implementations

vdev_cache_stats_hits Hits to the vdev (device level) cache.

vdev_cache_stats_misses Misses to the vdev (device level) cache.

ABD Stats (Linux Only)

ABD is a linear/scatter dual typed buffer for ARC

abdstats_linear_cnt number of linear ABDs which are currently allocated

abdstats_linear_data_size amount of data stored in all linear ABDs

abdstats_scatter_cnt number of scatter ABDs which are currently allocated

abdstats_scatter_data_size amount of data stored in all scatter ABDs

DMU Stats (Linux Only)

dmu_tx_dirty_throttle counts when writes are throttled due to the amount of dirty data growing too large

dmu_tx_memory_reclaim counts when memory is low and throttling activity

dmu_tx_memory_reserve counts when memory footprint of the txg exceeds the ARC size

Fault Management Ereport errors (Linux Only)

fm_erpt-dropped counts when an error report cannot be created (eg available memory is too low)

ZIL (Linux Only)

note: ZIL measurements are system-wide, neither per-pool nor per-dataset

zil_commit_count counts when ZFS transactions are committed to a ZIL