Inspecting a Node

When inspection of a Riak node to gather metrics on performance or potential issues is desired, a number of tools are available to help, and are either included with Riak itself or made available through the Riak community.

This guide provides starting points and details on some of the available tools for inspecting a Riak node.

riak-admin status

riak-admin status is a subcommand of the riak-admin command that is included with every installation of Riak. The status subcommand provides data related to the current operating status for a node. The output of riak-admin status is categorized and detailed below.

Please note, for some counters, such as node_get_fsm_objsize, a minimum of 5 transactions is required for statistics to be generated.

Performance

Please Note:

Due to a recent bug, executing riak-admin status more than once a minute can have an impact on performance. We recommended checking stats every 90-120 seconds due to this bug.

Repeated runs of the riak-admin status command does not have a negative performance impact as the statstics are cached internally in Riak.

Active Stats

Active Stats represent current activity on the node.

Stat Description
pbc_active Number of active Protocol Buffers connections
node_get_fsm_active Number of active GET FSMs
node_put_fsm_active Number of active PUT FSMs
index_fsm_active Number of active Secondary Index FSMs
list_fsm_active Number of active Keylisting FSMs
node_get_fsm_rejected Number of GET FSMs actively being rejected by Sidejob’s overload protection
node_put_fsm_rejected Number of PUT FSMs actively being rejected by Sidejob’s overload protection

Average Stats

Average Stats represent an average calculated as (total occurrences / number of samples) since this node was started. In the below stats the sample time is 1s, giving us a per-second average. Currently, the only Average Stats are reported by Sidejob - an Erlang library that implements a parallel, capacity-limited request pool.

Stat Description
node_get_fsm_in_rate Average number of GET FSMs enqueued by Sidejob
node_get_fsm_out_rate Average number of GET FSMs dequeued by Sidejob
node_put_fsm_in_rate Average number of PUT FSMs enqueued by Sidejob
node_put_fsm_out_rate Average number of PUT FSMs dequeued by Sidejob

One-Minute Stats

One-Minute Stats represent the number of times a particular activity has occurred within the last minute on this node.

General One-Minute Stats

Stat Description
node_gets Number of GETs coordinated by this node, including GETs to non-local vnodes in the last minute
node_puts Number of PUTs coordinated by this node, where a PUT is sent to a local vnode in the last minute
vnode_gets Number of GET operations coordinated by local vnodes on this node in the last minute
vnode_puts Number of PUT operations coordinated by local vnodes on this node in the last minute
vnode_index_refreshes Number of secondary indexes refreshed on this node during secondary index anti-entropy in the last minute
vnode_index_reads Number of local replicas participating in secondary index reads in the last minute
vnode_index_writes Number of local replicas participating in secondary index writes in the last minute
vnode_index_writes_postings Number of individual secondary index values written in the last minute
vnode_index_deletes Number of local replicas participating in secondary index deletes in the last minute
vnode_index_deletes_postings Number of individual secondary index values deleted in the last minute
pbc_connects Number of Protocol Buffers connections made in the last minute
node_get_fsm_active_60s Number of GET FSMs active in the last minute
node_put_fsm_active_60s Number of PUT FSMs active in the last minute
node_get_fsm_rejected_60s Number of GET FSMs rejected by Sidejob’s overload protection in the last minute
node_put_fsm_rejected_60s Number of PUT FSMs rejected by Sidejob’s overload protection in the last minute
index_fsm_create Number of Secondary Index query FSMs created in the last minute
index_fsm_create_error Number of Secondary Index query FSM creation errors in the last minute
list_fsm_create Number of Keylisting FSMs created in the last minute
list_fsm_create_error Number of Keylisting FSM creation errors in the last minute
read_repairs Number of read repair operations this node has coordinated in the last minute
read_repairs_primary_outofdate_one Number of read repair operations performed on primary vnodes in the last minute due to stale replicas
read_repairs_primary_notfound_one Number of read repair operations performed on primary vnodes in the last minute due to missing replicas
read_repairs_fallback_outofdate_one Number of read repair operations performed on fallback vnodes in the last minute due to stale replicas
read_repairs_fallback_notfound_one Number of read repair operations performed on fallback vnodes in the last minute due to missing replicas

FSM Time

FSM Time Stats represent the amount of time in microseconds required to traverse the GET or PUT Finite State Machine code, offering a picture of general node health. From your application’s perspective, FSM Time effectively represents experienced latency. Mean, Median, and 95th-, 99th-, and 100th-percentile (Max) counters are displayed. These are one-minute stats.

Stat Description
node_get_fsm_time_mean Mean time between reception of client GET request and subsequent response to client
node_get_fsm_time_median Median time between reception of client GET request and subsequent response to client
node_get_fsm_time_95 95th percentile time between reception of client GET request and subsequent response to client
node_get_fsm_time_99 99th percentile time between reception of client GET request and subsequent response to client
node_get_fsm_time_100 100th percentile time between reception of client GET request and subsequent response to client
node_put_fsm_time_mean Mean time between reception of client PUT request and subsequent response to client
node_put_fsm_time_median Median time between reception of client PUT request and subsequent response to client
node_put_fsm_time_95 95th percentile time between reception of client PUT request and subsequent response to client
node_put_fsm_time_99 99th percentile time between reception of client PUT request and subsequent response to client
node_put_fsm_time_100 100th percentile time between reception of client PUT request and subsequent response to client

GET FSM Siblings

GET FSM Sibling Stats offer a count of the number of siblings encountered by this node on the occasion of a GET request. These are one-minute stats.

Stat Description
node_get_fsm_siblings_mean Mean number of siblings encountered during all GET operations by this node within the last minute
node_get_fsm_siblings_median Median number of siblings encountered during all GET operations by this node within the last minute
node_get_fsm_siblings_95 95th percentile of siblings encountered during all GET operations by this node within the last minute
node_get_fsm_siblings_99 99th percentile of siblings encountered during all GET operations by this node within the last minute
node_get_fsm_siblings_100 100th percentile of siblings encountered during all GET operations by this node within the last minute

GET FSM Objsize

GET FSM Objsize Stats represent a view of the sizes of objects flowing through this node’s GET FSMs. The size of an object is obtained by summing the length of the bucket name, key, serialized vector clock, value, and serialized metadata of each sibling. GET FSM Objsize and GET FSM Siblings are inextricably linked. These are one-minute stats.

Stat Description
node_get_fsm_objsize_mean Mean object size (bytes) encountered by this node within the last minute
node_get_fsm_objsize_median Median object size (bytes) encountered by this node within the last minute
node_get_fsm_objsize_95 95th percentile object size (bytes) encountered by this node within the last minute
node_get_fsm_objsize_99 99th percentile object size (bytes) encountered by this node within the last minute
node_get_fsm_objsize_100 100th percentile object size (bytes) encountered by this node within the last minute

Total Stats

Total Stats represent the total number of times a particular activity has occurred since this node was started.

Stat Description
node_gets_total Total number of GETs coordinated by this node, including GETs to non-local vnodes
node_puts_total Total number of PUTs coordinated by this node, including PUTs to non-local vnodes
vnode_gets_total Total number of GETs coordinated by local vnodes
vnode_puts_total Total number of PUTS coordinated by local vnodes
read_repairs_total Total number of Read Repairs this node has coordinated
coord_redirs_total Total number of requests this node has redirected to other nodes for coordination
vnode_index_refreshes_total Total number of indexes refreshed during secondary index anti-entropy
vnode_index_reads_total Total number of local replicas participating in secondary index reads
vnode_index_writes_total Total number of local replicas participating in secondary index writes
vnode_index_writes_postings_total Total number of individual secondary index values written
vnode_index_deletes_total Total number of local replicas participating in secondary index deletes
vnode_index_deletes_postings_total Total number of individual secondary index values deleted
pbc_connects_total Total number of Protocol Buffers connections made
precommit_fail Total number of pre-commit hook failures
postcommit_fail Total number of post-commit hook failures
node_get_fsm_rejected_total Total number of GET FSMs rejected by Sidejob’s overload protection
node_put_fsm_rejected_total Total number of PUT FSMs rejected by Sidejob’s overload protection
read_repairs_primary_outofdate_count Total number of read repair operations performed on primary vnodes due to stale replicas
read_repairs_primary_notfound_count Total number of read repair operations performed on primary vnodes due to missing replicas
read_repairs_fallback_outofdate_count Total number of read repair operations performed on fallback vnodes due to stale replicas
read_repairs_fallback_notfound_count Total number of read repair operations performed on fallback vnodes due to missing replicas

Timestamps

Some of the Erlang applications that Riak is comprised of contribute statistics to riak-admin status. The below timestamps record, in Epoch time, the last time statistics for that application were generated.

Stat Description
riak_kv_stat_ts The last time Riak KV stats were generated.
riak_pipe_stat_ts The last time Riak Pipe stats were generated.

Ring

General ring information is reported in riak-admin status.

Stat Description
ring_members List of nodes that are members of the ring
ring_num_partitions The number of partitions in the ring
ring_ownership List of all nodes in the ring and their associated partition ownership
ring_creation_size Ring size this cluster was created with

CPU and Memory

CPU statistics are taken directly from Erlang’s cpu_sup module. Documentation for which can be found at ErlDocs: cpu_sup.

Stat Description
cpu_nprocs Number of operating system processes
cpu_avg1 The average number of active processes for the last 1 minute (equivalent to top(1) command’s load average when divided by 256())
cpu_avg5 The average number of active processes for the last 5 minutes (equivalent to top(1) command’s load average when divided by 256())
cpu_avg15 The average number of active processes for the last 15 minutes (equivalent to top(1) command’s load average when divided by 256())

Memory statistics are taken directly from the Erlang virtual machine. Documentation for which can be found at ErlDocs: Memory.

Stat Description
memory_total Total allocated memory (sum of processes and system)
memory_processes Total amount of memory allocated for Erlang processes
memory_processes_used Total amount of memory used by Erlang processes
memory_system Total allocated memory that is not directly related to an Erlang process
memory_atom Total amount of memory currently allocated for atom storage
memory_atom_used Total amount of memory currently used for atom storage
memory_binary Total amount of memory used for binaries
memory_code Total amount of memory allocated for Erlang code
memory_ets Total memory allocated for Erlang Term Storage
mem_total Total available system memory
mem_allocated Total memory allocated for this node

Erlang VM

The below statistics describe properties of the Erlang VM.

Stat Description
nodename The name this node uses to identify itself
connected_nodes A list of the nodes that this node is aware of at this time
sys_driver_version String representing the Erlang driver version in use by the runtime system
sys_global_heaps_size Current size of the shared global heap
sys_heap_type String representing the heap type in use (one of private, shared, hybrid)
sys_logical_processors Number of logical processors available on the system
sys_otp_release Erlang OTP release version in use on the node
sys_process_count Number of processes currently running in the Erlang VM
sys_smp_support Boolean value representing whether symmetric multi-processing (SMP) is available
sys_system_version Detailed Erlang version information
sys_system_architecture The node operating system and hardware architecture
sys_threads_enabled Boolean value representing whether threads are enabled
sys_thread_pool_size Number of threads in the asynchronous thread pool
sys_wordsize Size of Erlang term words in bytes as an integer, for examples, on 32-bit architectures 4 is returned and on 64-bit architectures 8 is returned

Miscellaneous Information

Miscellaneous Information provide additional details particular to this node.

Stat Description
leveldb_read_block_error The number of LevelDB read block errors. Will read as undefined if LevelDB is not being used.
disk Information about the disk, taken from Erlang’s disksup module. Reported as [{“ID”,KBytes_Used,Percent_Util}].
storage_backend The storage backend currently in use.

Pipeline Metrics

The following metrics from from riak_pipe are generated during MapReduce operations.

Stat Description
pipeline_active The number of pipelines active in the last 60 seconds
pipeline_create_count The total number of pipelines created since the node was started
pipeline_create_error_count The total number of pipeline creation errors since the node was started
pipeline_create_error_one The number of pipeline creation errors in the last 60 seconds
pipeline_create_one The number of pipelines created in the last 60 seconds

Application and Subsystem Versions

The specific version of each Erlang application and subsystem which makes up a Riak node is present in the riak-admin status output. Each application is linked below next to it’s version identifier.

Stat Description
erlydtl_version ErlyDTL
riak_control_version Riak Control
cluster_info_version Cluster Information
riak_search_version Riak Search
merge_index_version Merge Index
riak_kv_version Riak KV
sidejob_version Sidejob
riak_api_version Riak API
riak_pipe_version Riak Pipe
riak_core_version Riak Core
bitcask_version Bitcask
basho_stats_version Basho Stats
webmachine_version Webmachine
mochiweb_version MochiWeb
inets_version inets
erlang_js_version Erlang JS
runtime_tools_version Erlang Runtime Tools
os_mon_version Erlang Operating System Monitor
riak_sysmon_version Riak System Monitor
ssl_version Erlang Secure Sockets Layer (SSL)
public_key_version Erlang Public Key
crypto_version Erlang crypto
sasl_version SASL
lager_version Lager
goldrush_version Goldrush
compiler_version Erlang Compiler
syntax_tools_version Erlang Syntax Tools
stdlib_version Standard Library
kernel_version Kernel

Riak Search Statistics

The following statistics related to Riak Search message queues are available.

Stat Description
riak_search_vnodeq_max Maximum number of unprocessed messages all virtual node (vnode) message queues in the Riak Search subsystem have received on this node in the last minute
riak_search_vnodeq_mean Mean number of unprocessed messages all vnode message queues in the Riak Search subsystem have received on this node in the last minute
riak_search_vnodeq_median Median number of unprocessed messages all vnode message queues in the Riak Search subsystem have received on this node in the last minute
riak_search_vnodeq_min Minimum number of unprocessed messages all vnode message queues in the Riak Search subsystem have received on this node in the last minute
riak_search_vnodeq_total Total number of unprocessed messages all vnode message queues in the Riak Search subsystem have received on this node since it was started
riak_search_vnodes_running Total number of vnodes currently running in the Riak Search subsystem

Note that under ideal operation and with the exception of riak_search_vnodes_running these statistics should contain low values (e.g., 0-10). Presence of higher values could be indicative of an issue.

riak-debug

The riak-debug command is used to identify and diagnose common problems with your Riak KV nodes.

riak-debug also runs riak-admin diag, which runs a small suite of diagnostic checks against a Riak KV node to discover common problems. It often offers recommendations about how to resolve those problems as well.

Warning about riak-debug and riak-admin diag usage

The riak-debug and riak-admin diag commands should only be used after a new installation or configuration change. It should not be used as part of regular monitoring. Overuse of riak-debug or riak-admin diag can eventually cause the node to crash from atom table exhaustion.

Strong Consistency Stats

Riak tabulates a variety of stats related to Riak’s optional strong consistency feature. The table below lists those stats.

Stat Description
consistent_gets Number of strongly consistent GETs coordinated by this node in the last minute
consistent_gets_total Total number of strongly consistent GETs coordinated by this node
consistent_get_objsize_mean Mean object size (bytes) for strongly consistent GETs on this node in the last minute
consistent_get_objsize_median Median object size (bytes) for strongly consistent GETs on this node in the last minute
consistent_get_objsize_95 95th-percentile object size (bytes) for strongly consistent GETs on this node in the last minute
consistent_get_objsize_99 99th-percentile object size (bytes) for strongly consistent GETs on this node in the last minute
consistent_get_objsize_100 100th-percentile object size (bytes) for strongly consistent GETs on this node in the last minute
consistent_get_time_mean Mean time between reception of client GETs to strongly consistent keys and subsequent response
consistent_get_time_median Median time between reception of client GETs to strongly consistent keys and subsequent response
consistent_get_time_95 95th-percentile time between reception of client GETs to strongly consistent keys and subsequent response
consistent_get_time_99 99th-percentile time between reception of client GETs to strongly consistent keys and subsequent response
consistent_get_time_100 100th-percentile time between reception of client GETs to strongly consistent keys and subsequent response
Stat Description
consistent_puts Number of strongly consistent PUTs coordinated by this node in the last minute
consistent_puts_total Total number of strongly consistent PUTs coordinated by this node
consistent_put_objsize_mean Mean object size (bytes) for strongly consistent PUTs on this node in the last minute
consistent_put_objsize_median Median object size (bytes) for strongly consistent PUTs on this node in the last minute
consistent_put_objsize_95 95th-percentile object size (bytes) for strongly consistent PUTs on this node in the last minute
consistent_put_objsize_99 99th-percentile object size (bytes) for strongly consistent PUTs on this node in the last minute
consistent_put_objsize_100 100th-percentile object size (bytes) for strongly consistent PUTs on this node in the last minute
consistent_put_time_mean Mean time between reception of client PUTs to strongly consistent keys and subsequent response
consistent_put_time_median Median time between reception of client PUTs to strongly consistent keys and subsequent response
consistent_put_time_95 95th-percentile time between reception of client PUTs to strongly consistent keys and subsequent response
consistent_put_time_99 99th-percentile time between reception of client PUTs to strongly consistent keys and subsequent response
consistent_put_time_100 100th-percentile time between reception of client PUTs to strongly consistent keys and subsequent response

riak-admin diag

Running riak-admin diag by itself will perform a check of all of the data partitions in your cluster. It will return a listing of partitions that have been checked, each of which looks something like this:

{1392993748081016843912887106182707253109560705024, % the partition checked
 'dev-rel@127.0.0.1'},                              % that partition's nodename

At the end of that (potentially very long) listing of checked partitions, it will print notices, warnings, and other pieces of information about issues that it has found, including date/time, message type, and a detailed description. Here’s an example:

15:34:52.736 [warning] Riak crashed at Wed, 07 Dec 2011 21:47:50 GMT, leaving crash dump in /srv/riak/log/erl_crash.dump. Please inspect or remove the file.
15:34:52.736 [notice] Data directory /srv/riak/data/bitcask is not mounted with 'noatime'. Please remount its disk with the 'noatime' flag to improve performance.

Messages bear the following types (derived from syslog security levels):

  • debug
  • info
  • notice
  • warning
  • error
  • critical
  • alert
  • emergency

Command flags

Attaching the --help flag will return a list of flags and commands that can be used with Riaknostic:

Usage: riak-admin diag [-d <level>] [-l] [-h] [--export] [check_name ...]

-h, --help            Display help/usage dialogue
-d, --level           Minimum message severity level (default: notice)
-l, --list            Describe available diagnostic tasks
--export              Package system info in '/export.zip'
check_name            A specific check to run

Running riak-admin diag with the --list flag will return a list of available diagnostic checks. The following checks are available:

Check Description
disk Data directory permissions and atime
dumps Find crash dumps
memory_use Measure memory usage
nodes_connected Cluster node liveness
ring_membership Cluster membership validity
ring_preflists Check if the ring satisfies n_val
ring_size Check if the ring size valid
search Check whether Riak Search is enabled on all nodes

The --level flag enables you to specify the log level and thus to filter messages based on type. You can pass in any of the message types listed above (debug, info, etc.).

The --level flag can be used when running riak-admin diag with or without specifying a diagnostic check.

Contributing

Do you have an idea that would help us improve Riaknostic? If so, fork the GitHub repository and send us a pull request with your changes. The code is documented with edoc, so give the API Docs a read before you contribute.

If you want to run the Riaknostic script while developing and you don’t have it hooked up to your local Riak installation, you can invoke it directly like so:

./riaknostic --etc ~/code/riak/rel/riak/etc --base ~/code/riak/rel/riak --user `whoami` [other options]

Those extra options are usually assigned by the riak-admin script for you, but here’s how to set them:

  • --etc — The location of your Riak configuration directory (usually /etc). In the example above, configuration is in the generated directory of a source checkout of Riak.
  • --base — The “base” directory of Riak, usually the root of the generated directory or /usr/lib/riak on Linux. Scan the riak-admin script for how the RUNNER_BASE_DIR variable is assigned on your platform.
  • --user — The user/UID as which the Riak node runs. In a source checkout, it’s the current user; on most systems, it’s riak.