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Monitoring and Metrics

Riak S2 (CS) includes metrics and operational statistics to help you monitor your system in more detail and diagnose system issues more easily. There are three major categories of metrics:

  1. Frontend API performance
  2. Backend Riak performance (Stanchion)
  3. S2 internal performance

Metrics are also available for Stanchion, in addition to the Stanchion-specific stanchion-admin command and /stats HTTP endpoint.

provides operational statistics that can be useful for monitoring through the Folsom statistics library, and initial probes for analysis of the running system with DTrace.

Note: Older Versions of Riak S2

All statistics available in versions of Riak S2 below 2.0.x have either been renamed or removed entirely.

Using Metrics

Riak S2 exposes statistics on critical operations that are commonly used for monitoring, alerting, and trend analysis. These statistics can be accessed through the command line:

riak-cs-admin status

or through HTTP requests to the following resource:

/riak-cs/stats

Note

In order to access statistics from the /stats endpoint, you must issue signed requests containing the admin user's access key and secret key. The interface used by Riak S2 is directly analogous to that of Amazon S3. For more information on signed requests, see Amazon's documentation.

Unsigned requests will yield a 403 Forbidden error.

riak-cs-admin status

Running riak-cs-admin status will show the names and values of all available metrics.

There are too many metrics (over 1000) to list all of them here. The following sections provide an overview of each major statistic category, associated prefixes, and major operations for that category.

S3 API statistics

S3 API statistics start with one of the following prefixes (all of which are names for S3 APIs):

Each prefix is typically followed by operations such as:

Operation Description
service_get GET Service
bucket_(put head
bucketacl(get put)
bucketpolicy(get put
bucket_location_get GET Bucket Location
list_uploads listing all multipart uploads
multiple_delete Delete Multiple Objects
list_objects listing all objects in a bucket, equally GET Bucket
object_(get put
object_put_copy PUT Copy Object
object_acl GET, PUT Object ACL
multipart_post Initiate a multipart upload
multipart_upload_put PUT Multipart Upload, putting a part of an object by copying from existing object
multipart_upload_post complete a multipart upload
multipart_upload_delete delete a part of a multipart upload
multipart_upload_get get a list of parts in a multipart upload

See the S3 API documentation for information on all available APIs.

Stanchion access statistics

Stanchion access statistics start with the prefix velvet.

These statistics cover latency and counts for the Stanchion process creating/updating/deleting buckets or creating users. Stanchion access statistics can help determine if latency or slow requests are in Stanchion.

Operation Description
velvet_create_user requesting creating a user to Stanchion
velvet_update_user requesting updating a user to Stanchion
velvet_create_bucket requesting creating a bucket to Stanchion
velvet_delete_bucket requesting deleting a bucket to Stanchion
velvet_set_bucket_acl requesting updating a bucket ACL to Stanchion
velvet_set_bucket_policy requesting putting a new bucket policy to Stanchion
velvet_delete_bucket_policy requesting deleting a policy of the bucket to Stanchion

Riak access statistics

Riak access statistics start with the prefix riakc.

These statistics cover latency and call counts to Riak PB API. Riak access statistics are useful in determining the source of latency. For example getting a user record, bucket record, or updating manifests.

The riakc prefix is typically followed by operations like:

And their targets, such as manifests or blocks.

Operation Description
riakc_ping ping PB API. invoked by /riak-cs/ping
riakc_get_cs_bucket getting a bucket record
riakc_get_cs_user_strong getting a user record with PR=all
riakc_get_cs_user getting a user record with R=quorum and PR=one
riakc_put_cs_user putting a user record after create/deleting a bucket
riakc_get_manifest getting a manifest
riakc_put_manifest putting a manifest
riakc_delete_manifest deleting a manifest (invoked via GC)
riakc_get_block_n_one getting a block with N=1 without sloppy quorum
riakc_get_block_n_all getting a block with N=3 after N=1 get failed
riakc_get_block_remote getting a block after N=3 get resulted in not found
riakc_get_block_legacy getting a block when N=1 get is turned off
riakc_put_block putting a block
riakc_put_block_resolved putting a block when block siblings resolution is invoked
riakc_head_block heading a block, invoked via GC
riakc_delete_block_constrained first trial to delete block with PW=all
riakc_delete_block_secondary second trial to delete block with PW=quorum, after PW=all failed
riakc_(get put)_gc_manifest_set
riakc_(get delete)_gc_manifest_set
riakc_(get put)_access
riakc_(get put)_storage
riakc_fold_manifest_objs invoked inside GET Bucket (listing objects within a bucket)
riakc_mapred_storage stats on each MapReduce job performance
riakc_list_all_user_keys all users are listed out when starting storage calculation
riakc_list_all_manifest_keys only used when deleting a bucket to verify it's empty
riakc_list_users_receive_chunk listing users invoked via /riak-cs/users API.
riakc_get_uploads_by_index
riakc_get_user_by_index
riakc_get_gc_keys_by_index
riakc_get_cs_buckets_by_index
riakc_get_clusterid invoked when for the first time when a proxy_get is performed

/riak-cs/stats

That will return a JSON object containing a series of latency histograms and counters for a variety of operations, e.g. object_get and block_put. Alongside each operation there will be a list showing the count and rate for the operation, as well as a latency histogram showing mean, median, and 95th and 99th percentiles:

<operation_name>: [MeterCount, MeterRate, LatencyMean, LatencyMedian, Latency95, Latency99]

You will see a list of that form for each of the following operations:

Operation Description
block_get Total BLOCK GET operations performed
block_put Total BLOCK GET operations performed
block_delete Total BLOCK DELETE operations performed
service_get_buckets Total GET BUCKETS operations performed
bucket_list_keys Total BUCKET LIST KEYS operations performed
bucket_create Total BUCKET CREATE operations performed
bucket_delete Total BUCKET DELETE operations performed
bucket_get_acl Total BUCKET GET ACL operations performed
bucket_put_acl Total BUCKET PUT ACL operations performed
object_get Total GET operations performed
object_put Total PUT operations performed
object_head Total OBJECT HEAD operations performed
object_delete Total OBJECT DELETE operations performed
object_get_acl Total OBJECT GET ACL operations performed
object_put_acl Total OBJECT PUT ACL operations performed

Stanchion

DTrace Probes

Riak CS is built with some probes for use with DTrace to inspect certain operations in the live system, which can be helpful in diagnosing issues.

Usage Examples

The following are examples of using DTrace for inspecting various components of a running Riak CS installation.

Trace User Object Requests

dtrace -qn 'erlang*:::user_trace* /arg2 == 703/ {printf("pid %s: mod %s op %s: user %s bucket/file %s\n", copyinstr(arg0), copyinstr(arg6), copyinstr(arg7), copyinstr(arg8), copyinstr(arg9));}'

Trace Webmachine Resource Execution

dtrace -qn 'erlang*:::user_trace* /arg2 == 705/ {printf("pid %s: %s:%s\n", copyinstr(arg0), copyinstr(arg6), copyinstr(arg7));}'
Note on DTrace Support

Work on packaging of Riak CS for SmartOS and other operating systems with DTrace support is ongoing with the goal of providing enhanced ability to diagnose low-level issues in instances of Riak CS running on such operating systems.