Merge pull request #236 from daira/2725.timezone-test.0

[tahoe-lafs/tahoe-lafs.git] / docs / stats.rst

diff --git a/docs/stats.rst b/docs/stats.rst
index 47f6b04b78888a2fe29c8801d6576ec3f85dbb73..0e151fbf31b031fb21fe056fbf837d7ee3b8a0a4 100644 (file)
--- a/docs/stats.rst
+++ b/docs/stats.rst
@@ -1,3 +1,5 @@
+.. -*- coding: utf-8-with-signature -*-
+
 ================
 Tahoe Statistics
 ================
@@ -44,7 +46,7 @@ The currently available stats (as of release 1.6.0 or so) are described here:
     this group counts inbound storage-server operations. They are not provided
     by client-only nodes which have been configured to not run a storage server
     (with [storage]enabled=false in tahoe.cfg)
-                           
+
     allocate, write, close, abort
         these are for immutable file uploads. 'allocate' is incremented when a
         client asks if it can upload a share to the server. 'write' is
@@ -134,6 +136,14 @@ The currently available stats (as of release 1.6.0 or so) are described here:
         999 out of the last 1000 operations were faster than the
         given number, and is the same threshold used by Amazon's
         internal SLA, according to the Dynamo paper).
+        Percentiles are only reported in the case of a sufficient
+        number of observations for unambiguous interpretation. For
+        example, the 99.9th percentile is (at the level of thousandths
+        precision) 9 thousandths greater than the 99th
+        percentile for sample sizes greater than or equal to 1000,
+        thus the 99.9th percentile is only reported for samples of 1000
+        or more observations.
+
 
 **counters.uploader.files_uploaded**
 
@@ -195,7 +205,7 @@ The currently available stats (as of release 1.6.0 or so) are described here:
 
     active_uploads
         how many files are currently being uploaded. 0 when idle.
-    
+
     incoming_count
         how many cache files are present in the incoming/ directory,
         which holds ciphertext files that are still being fetched
@@ -297,7 +307,7 @@ keep its FURL consistent). To explicitly control which port it uses, write
 the desired portnumber into a file named "portnum" (i.e. $BASEDIR/portnum),
 and the next time the gatherer is started, it will start listening on the
 given port. The portnum file is actually a "strports specification string",
-as described in docs/configuration.txt .
+as described in configuration.rst_.
 
 Once running, the stats gatherer will create a standard python "pickle" file
 in $BASEDIR/stats.pickle . Once a minute, the gatherer will pull stats
@@ -314,6 +324,8 @@ something useful. For example, a tool could sum the
 total-disk-available number for the entire grid (however, the "disk watcher"
 daemon, in misc/operations_helpers/spacetime/, is better suited for this specific task).
 
+.. _configuration.rst: configuration.rst
+
 Using Munin To Graph Stats Values
 =================================
 
@@ -323,8 +335,6 @@ typically polls target systems every 5 minutes and produces a web page with
 graphs of various things over multiple time scales (last hour, last month,
 last year).
 
-.. _Munin: http://munin-monitoring.org/
-
 Most of the plugins are designed to pull stats from a single Tahoe node, and
 are configured with the e.g. http://localhost:3456/statistics?t=json URL. The
 "tahoe_stats" plugin is designed to read from the pickle file created by the
@@ -335,3 +345,5 @@ stats-gatherer. Some plugins are to be used with the disk watcher, and a few
 Please see the docstrings at the beginning of each plugin for details, and
 the "tahoe-conf" file for notes about configuration and installing these
 plugins into a Munin environment.
+
+.. _Munin: http://munin-monitoring.org/