@@ -12,7 +12,7 @@ allow you to diagnose issues as you encounter them, rather than
1212waiting for a crisis or failure.
1313
1414This document provides an overview of the available tools and data
15- provided by MongoDB as well as introduction to diagnostic strategies,
15+ provided by MongoDB as well as an introduction to diagnostic strategies,
1616and suggestions for monitoring instances in MongoDB's replica sets and
1717sharded clusters.
1818
@@ -89,7 +89,7 @@ MongoDB provides a number of commands that return
8989statistics about the state of the MongoDB instance. These data may
9090provide finer granularity regarding the state of the MongoDB instance
9191than the tools above. Consider using their output in scripts and
92- programs to develop custom alerts, or modifying the behavior of your
92+ programs to develop custom alerts, or to modify the behavior of your
9393application in response to the activity of your instance.
9494
9595``serverStatus``
@@ -203,7 +203,7 @@ on your own servers, usually open source.
203203 - `mikoomi-mongodb <https://code.google.com/p/mikoomi/wiki/03>`_
204204 - Monitors availability, resource utilization, health, performance and other important metrics.
205205
206- Also consider `dex <https://github.com/mongolab/dex>`_, and index and
206+ Also consider `dex <https://github.com/mongolab/dex>`_, an index and
207207query analyzing tool for MongoDB that compares MongoDB log files and
208208indexes to make indexing recommendations.
209209
@@ -233,10 +233,10 @@ Process Logging
233233During normal operation, :program:`mongod` and :program:`mongos`
234234instances report information that reflect current operation to
235235standard output, or a log file. The following runtime settings
236- methods to control these options.
236+ control these options.
237237
238238- :setting:`quiet`. Limits the amount of information written to the
239- log our output.
239+ log or output.
240240
241241- :setting:`verbose`. Increases the amount of information written to
242242 the log or output.
@@ -260,6 +260,7 @@ methods to control these options.
260260 </reference/mongos>`
261261
262262Additionally, the following :term:`database commands <database command>`
263+ affect logging:
263264
264265- :dbcommand:`getLog`. Displays recent messages from the :program:`mongod` process log.
265266
@@ -270,7 +271,7 @@ Diagnosing Performance Issues
270271-----------------------------
271272
272273Degraded performance in MongoDB can be the result of an array of
273- causes, and is typically a function of the relationship between the
274+ causes, and is typically a function of the relationship among the
274275quantity of data stored in the database, the amount of system RAM, the
275276number of connections to the database, and the amount of time the
276277database spends in a lock state.
@@ -281,19 +282,20 @@ the host system for virtualized environments. Some users also
281282experience performance limitations as a result of inadequate or
282283inappropriate indexing strategies, or as a consequence of poor schema
283284design patterns. In other situations, performance issues may indicate
284- that the database may be operating at capacity and that it's time to
285+ that the database may be operating at capacity and that it is time to
285286add additional capacity to the database.
286287
287288Locks
288289~~~~~
289290
290- MongoDB uses a locking system to ensure consistency; however , if
291+ MongoDB uses a locking system to ensure consistency. However , if
291292certain operations are long-running, or a queue forms, performance
292293slows as requests and operations wait for the lock. Because lock
293294related slow downs can be intermittent, look to the data in the
294295:ref:`globalLock` section of the :dbcommand:`serverStatus` response to
295- asses if the lock has been a challenge to your performance. If
296- :data:`globalLock.currentQueue.total <serverStatus.globalLock.currentQueue.total>` is consistently high, then
296+ assess if the lock has been a challenge to your performance. If
297+ :data:`globalLock.currentQueue.total <serverStatus.globalLock.currentQueue.total>`
298+ is consistently high, then
297299there is a chance that a large number of requests are waiting for a
298300lock. This indicates a possible concurrency issue that might affect
299301performance.
@@ -343,6 +345,8 @@ check for page faults, see the :data:`extra_info.page_faults
343345:dbcommand:`serverStatus` command. This data is only available on
344346Linux systems.
345347
348+ .. we should reverify the previous statement as the info is appearing on OS X as well
349+
346350Alone, page faults are minor and complete quickly; however, in
347351aggregate, large numbers of page fault typically indicate that MongoDB
348352is reading too much data from disk and can indicate a number of
@@ -355,7 +359,7 @@ this also improves overall throughput.
355359If possible, increasing the amount of RAM accessible to MongoDB may
356360help reduce the number of page faults. If this is not possible, you
357361may want to consider deploying a :term:`sharded cluster` and/or
358- adding one or more :term:`shards <shard>` to your deployment to
362+ adding one or more :term:`shards <shard>` to your deployment to
359363distribute load among :program:`mongod` instances.
360364
361365Number of Connections
@@ -440,7 +444,7 @@ The following profiling levels are available:
440444=========== ======================================
441445
442446See the output of the profiler in the ``system.profile`` collection of
443- your database. You can specify the :setting:`slowms` to set a
447+ your database. You can specify the :setting:`slowms` setting to set a
444448threshold above which the profiler considers operations "slow" and
445449thus included in the level ``1`` profiling data. You may configure
446450:setting:`slowms` at runtime, as an argument to the
@@ -472,7 +476,7 @@ Replication and Monitoring
472476--------------------------
473477
474478The primary administrative concern that requires monitoring with
475- replica sets, beyond the requirements for any MongoDB instance is
479+ replica sets, beyond the requirements for any MongoDB instance, is
476480"replication lag." This refers to the amount of time that it takes a
477481write operation on the :term:`primary` to replicate to a
478482:term:`secondary`. Some very small delay period may be acceptable;
@@ -551,7 +555,7 @@ Balancing and Chunk Distribution
551555~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
552556
553557The most effective :term:`sharded cluster` deployments require that
554- :term:`chunks <chunk>` are evenly balanced between the shards. MongoDB
558+ :term:`chunks <chunk>` are evenly balanced among the shards. MongoDB
555559has a background :term:`balancer` process that distributes data such that
556560chunks are always optimally distributed among the :term:`shards <shard>`.
557561Issue the :method:`db.printShardingStatus()` or :method:`sh.status()`
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