[DOCS] Clarify definition of max_size (#56561) (#56648)

* [DOCS] Extract the cron docs from Watcher docs and add to the API conventions. (#56313)

* [DOCS] Promote cron expressions info from Watcher to a separate topic.

* Fix table error

* Fixed xref

* Apply suggestions from code review

Co-authored-by: James Rodewig <[email protected]>

* Incorporated review feedback

Co-authored-by: James Rodewig <[email protected]>

* [DOCS] Clarify definition of max_size (#56561)

Co-authored-by: James Rodewig <[email protected]>

docs/reference/api-conventions.asciidoc

@@ -8,6 +8,7 @@ API, unless otherwise specified.
 
 * <<multi-index>>
 * <<date-math-index-names>>
+* <<cron-expressions>>
 * <<common-options>>
 * <<url-access-control>>
 
@@ -143,6 +144,8 @@ GET /%3Clogstash-%7Bnow%2Fd-2d%7D%3E%2C%3Clogstash-%7Bnow%2Fd-1d%7D%3E%2C%3Clogs
 // TEST[s/^/PUT logstash-2016.09.20\nPUT logstash-2016.09.19\nPUT logstash-2016.09.18\n/]
 // TEST[s/now/2016.09.20||/]
 
+include::rest-api/cron-expressions.asciidoc[]
+
 [[common-options]]
 === Common options
 

docs/reference/commands/croneval.asciidoc

@@ -3,7 +3,7 @@
 [[elasticsearch-croneval]]
 == elasticsearch-croneval
 
-Validates and evaluates a cron expression. 
+Validates and evaluates a <<cron-expressions,cron expression>>. 
 
 [discrete]
 === Synopsis
@@ -19,12 +19,11 @@ bin/elasticsearch-croneval <expression>
 === Description
 
 This command enables you to verify that your
-https://en.wikipedia.org/wiki/Cron[cron] expressions are valid for use with the
-{es} {alert-features} and produce the expected results.
+cron expressions are valid for use with
+{es} and produce the expected results.
 
 This command is provided in the `$ES_HOME/bin` directory.
 
-[discrete]
 === Parameters
 
 `-c, --count` <Integer>::
@@ -45,7 +44,7 @@ This command is provided in the `$ES_HOME/bin` directory.
   Shows verbose output.
 
 [discrete]
-=== Examples
+=== Example
 
 If the cron expression is valid, the following command displays the next
 20 times that the schedule will be triggered:

docs/reference/ilm/actions/ilm-rollover.asciidoc

@@ -43,19 +43,24 @@ PUT my_index-000001
 You must specify at least one rollover condition. 
 An empty rollover action is invalid.
 
-`max_size`::
-(Optional, <<byte-units, byte units>>)
-Triggers roll over after the specified maximum primary shard index storage size is reached.  
+`max_age`::
+(Optional,  <<time-units, time units>>)  
+Triggers roll over after the maximum elapsed time from index creation is reached. 
 
 `max_docs`::
 (Optional, integer)
 Triggers roll over after the specified maximum number of documents is reached.
 Documents added since the last refresh are not included in the document count.
 The document count does *not* include documents in replica shards.
 
-`max_age`::
-(Optional,  <<time-units, time units>>)  
-Triggers roll over after the maximum elapsed time from index creation is reached. 
+`max_size`::
+(Optional, <<byte-units, byte units>>)
+Triggers roll over when the index reaches a certain size.
+This is the total size of all primary shards in the index. 
+Replicas are not counted toward the maximum index size.
++
+TIP: To see the current index size, use the <<cat-indices, _cat indices>> API. 
+The `pri.store.size` value shows the combined size of all primary shards.
 
 [[ilm-rollover-ex]]
 ==== Example

docs/reference/ilm/using-policies-rollover.asciidoc

@@ -4,10 +4,17 @@
 == Configure rollover
 [[using-policies-rollover]]
 You control when the rollover action is triggered by specifying one or more
-rollover parameters. The rollover is performed once any of the criteria are
-met. Because the criteria are checked periodically, the index might grow
-slightly beyond the specified threshold. To control how often the criteria are
-checked, specify the `indices.lifecycle.poll_interval` cluster setting.
+rollover criteria:
+
+* Maximum size (the combined size of all primary shards in the index)
+* Maximum document count
+* Maximum age
+
+The rollover is performed once any of the criteria are met. 
+Because the criteria are checked periodically, the index might grow
+slightly beyond the specified threshold. 
+To control how often the criteria are checked, 
+specify the `indices.lifecycle.poll_interval` cluster setting.
 
 IMPORTANT: New indices created via rollover will not automatically inherit the
 policy used by the old index, and will not use any policy by default. Therefore,
@@ -16,24 +23,6 @@ it is highly recommended to apply the policy via
 setting, for your indices which specifies the policy you wish to use for each
 new index.
 
-The rollover action takes the following parameters:
-
-[[rollover-action-params]]
-.`rollover` Action Parameters
-[options="header"]
-|===
-|Name |Description
-|max_size |The maximum estimated size the primary shard of the index is allowed
-to grow to. Defaults to `null`. Optional.
-|max_docs |The maximum number of document the index should
-contain. Defaults to `null`. Optional.
-|max_age |The maximum age of the index. Defaults to `null`. Optional.
-|===
-
-These parameters are used to determine when the index is considered "full" and
-a rollover should be performed. Where multiple criteria are defined the
-rollover operation will be performed once any of the criteria are met.
-
 The following request defines a policy with a rollover action that triggers
 when the index size reaches 25GB. The old index is subsequently deleted after
 30 days.
@@ -127,7 +116,7 @@ the new index, enabling indexing to continue uninterrupted.
 [[skipping-rollover]]
 === Skipping Rollover
 
-The `index.lifecycle.indexing_complete` setting indicates to {ilm} whether this
+The `index.lifecycle.indexing_complete` setting indicates to {ilm-init} whether this
 index has already been rolled over. If it is set to `true`, that indicates that
 this index has already been rolled over and does not need to be rolled over
 again. Therefore, {ilm} will skip any Rollover Action configured in the

docs/reference/indices/rollover-index.asciidoc

@@ -145,7 +145,12 @@ The document count does *not* include documents in replica shards.
 
 `max_size`::
 (Optional, <<byte-units, byte units>>)
-Maximum estimated size of the primary shard of the index.
+Maximum index size. 
+This is the total size of all primary shards in the index. 
+Replicas are not counted toward the maximum index size.
+
+TIP: To see the current index size, use the <<cat-indices, _cat indices>> API. 
+The `pri.store.size` value shows the combined size of all primary shards. 
 --
 
 include::{docdir}/rest-api/common-parms.asciidoc[tag=mappings]

docs/reference/rest-api/cron-expressions.asciidoc

@@ -0,0 +1,182 @@
+[[cron-expressions]]
+=== Cron expressions
+
+A cron expression is a string of the following form:
+
+[source,txt]
+------------------------------
+    <seconds> <minutes> <hours> <day_of_month> <month> <day_of_week> [year]
+------------------------------
+
+{es} uses the cron parser from the http://www.quartz-scheduler.org[Quartz Job Scheduler]. 
+For more information about writing Quartz cron expressions, see the
+http://www.quartz-scheduler.org/documentation/quartz-2.2.x/tutorials/tutorial-lesson-06.html[Quartz CronTrigger Tutorial].
+
+All schedule times are in coordinated universal time (UTC); other timezones are not supported.
+
+TIP: You can use the <<elasticsearch-croneval>> command line tool to validate your cron expressions.
+
+
+[[cron-elements]]
+==== Cron expression elements
+
+All elements are required except for `year`. 
+See <<cron-special-characters>> for information about the allowed special characters.
+
+`<seconds>`::
+(Required)
+Valid values: `0`-`59` and the special characters `,` `-` `*` `/`
+
+`<minutes>`:: 
+(Required)
+Valid values: `0`-`59` and the special characters `,` `-` `*` `/`
+
+`<hours>`:: 
+(Required)
+Valid values: `0`-`23` and the special characters `,` `-` `*` `/`
+
+`<day_of_month>`:: 
+(Required)
+Valid values: `1`-`31` and the special characters `,` `-` `*` `/` `?` `L` `W`
+
+`<month>`::  
+(Required)
+Valid values: `1`-`12`, `JAN`-`DEC`, `jan`-`dec`, and the special characters `,` `-` `*` `/`
+
+`<day_of_week>`:: 
+(Required)
+Valid values: `1`-`7`, `SUN`-`SAT`, `sun`-`sat`,  and the special characters `,` `-` `*` `/` `?` `L` `#`
+
+`<year>`:: 
+(Optional)
+Valid values: `1970`-`2099` and the special characters `,` `-` `*` `/`
+
+[[cron-special-characters]]
+==== Cron special characters
+
+`*`::
+Selects every possible value for a field. For
+example, `*` in the `hours` field means "every hour".
+
+`?`::                
+No specific value. Use when you don't care what the value
+is. For example, if you want the schedule to trigger on a
+particular day of the month, but don't care what day of
+the week that happens to be, you can specify `?` in the
+`day_of_week` field.
+
+`-`::                 
+A range of values (inclusive). Use to separate a minimum
+and maximum value. For example, if you want the schedule
+to trigger every hour between 9:00 a.m. and 5:00 p.m., you
+could specify `9-17` in the `hours` field.
+
+`,`::
+Multiple values. Use to separate multiple values for a
+field. For example, if you want the schedule to trigger
+every Tuesday and Thursday, you could specify `TUE,THU`
+in the `day_of_week` field.
+
+`/`::
+Increment. Use to separate values when specifying a time
+increment. The first value represents the starting point,
+and the second value represents the interval. For example,
+if you want the schedule to trigger every 20 minutes
+starting at the top of the hour, you could specify `0/20`
+in the `minutes` field. Similarly, specifying `1/5` in
+`day_of_month` field will trigger every 5 days starting on
+the first day of the month.
+
+`L`::
+Last. Use in the `day_of_month` field to mean the last day
+of the month--day 31 for January, day 28 for February in
+non-leap years, day 30 for April, and so on. Use alone in
+the `day_of_week` field in place of `7` or `SAT`, or after
+a particular day of the week to select the last day of that
+type in the month. For example `6L` means the last Friday
+of the month. You can specify `LW` in the `day_of_month`
+field to specify the last weekday of the month. Avoid using
+the `L` option when specifying lists or ranges of values,
+as the results likely won't be what you expect.
+
+`W`::
+Weekday. Use to specify the weekday (Monday-Friday) nearest
+the given day. As an example, if you specify `15W` in the
+`day_of_month` field and the 15th is a Saturday, the
+schedule will trigger on the 14th. If the 15th is a Sunday,
+the schedule will trigger on Monday the 16th. If the 15th
+is a Tuesday, the schedule will trigger on Tuesday the 15th.
+However if you specify `1W` as the value for `day_of_month`,
+and the 1st is a Saturday, the schedule will trigger on
+Monday the 3rd--it won't jump over the month boundary. You
+can specify `LW` in the `day_of_month` field to specify the
+last weekday of the month. You can only use the `W` option
+when the `day_of_month` is a single day--it is not valid
+when specifying a range or list of days.
+
+`#`::
+Nth XXX day in a month. Use in the `day_of_week` field to
+specify the nth XXX day of the month. For example, if you
+specify `6#1`, the schedule will trigger on the first
+Friday of the month. Note that if you specify `3#5` and
+there are not 5 Tuesdays in a particular month, the
+schedule won't trigger that month.
+
+[[cron-expression-examples]]
+==== Examples
+
+[[cron-example-daily]]
+===== Setting daily triggers
+
+`0 5 9 * * ?`::
+Trigger at 9:05 a.m. UTC every day.
+
+`0 5 9 * * ? 2020`::
+Trigger at 9:05 a.m. UTC every day during the year 2020.
+
+[[cron-example-range]]
+===== Restricting triggers to a range of days or times
+
+`0 5 9 ? * MON-FRI`::
+Trigger at 9:05 a.m. UTC Monday through Friday.
+
+`0 0-5 9 * * ?`::
+Trigger every minute starting at 9:00 a.m. UTC and ending at 9:05 a.m. UTC every day.
+
+[[cron-example-interval]]
+===== Setting interval triggers
+
+`0 0/15 9 * * ?`::
+Trigger every 15 minutes starting at 9:00 a.m. UTC and ending at 9:45 a.m. UTC every day.
+
+`0 5 9 1/3 * ?`::
+Trigger at 9:05 a.m. UTC every 3 days every month, starting on the first day of the month.
+
+[[cron-example-day]]
+===== Setting schedules that trigger on a particular day
+
+`0 1 4 1 4 ?`::
+Trigger every April 1st at 4:01 a.m. UTC.
+`0 0,30 9 ? 4 WED`::
+Trigger at 9:00 a.m. UTC and at 9:30 a.m. UTC every Wednesday in the month of April.
+
+`0 5 9 15 * ?`::
+Trigger at 9:05 a.m. UTC on the 15th day of every month.
+
+`0 5 9 15W * ?`::
+Trigger at 9:05 a.m. UTC on the nearest weekday to the 15th of every month.
+
+`0 5 9 ? * 6#1`::
+Trigger at 9:05 a.m. UTC on the first Friday of every month.
+
+[[cron-example-last]]
+===== Setting triggers using last
+
+`0 5 9 L * ?`::
+Trigger at 9:05 a.m. UTC on the last day of every month.
+
+`0 5 9 ? * 2L`::
+Trigger at 9:05 a.m. UTC on the last Monday of every month.
+
+`0 5 9 LW * ?`::
+Trigger at 9:05 a.m. UTC on the last weekday of every month.

docs/reference/slm/apis/slm-put.asciidoc

@@ -106,7 +106,7 @@ Minimum number of snapshots to retain, even if the snapshots have expired.
 ====
 
 `schedule`::
-(Required, <<schedule-cron,Cron scheduler configuration>>)
+(Required, <<cron-expressions,Cron syntax>>)
 Periodic or absolute schedule at which the policy creates snapshots and deletes 
 expired snapshots. Schedule changes to existing policies are applied immediately.
 

docs/reference/slm/getting-started-slm.asciidoc

@@ -112,7 +112,8 @@ This is useful for taking snapshots before making a configuration change,
 upgrading, or to test a new policy. 
 Manually executing a policy does not affect its configured schedule. 
 
-For example, the following request manually triggers the `nightly-snapshots` policy:
+Instead of waiting for the policy to run, tell {slm-init} to take a snapshot
+using the configuration right now instead of waiting for 1:30 a.m..
 
 [source,console]
 --------------------------------------------------
@@ -159,19 +160,25 @@ repository is lost while copying files.
         "max_count": 50
       }
     },
-    "last_success": { 
-      "snapshot_name": "nightly-snap-2019.04.24-tmtnyjtrsxkhbrrdcgg18a", <1>
-      "time_string": "2019-04-24T16:43:49.316Z", <2>
+    "last_success": {                                                    <1>
+      "snapshot_name": "nightly-snap-2019.04.24-tmtnyjtrsxkhbrrdcgg18a", <2>
+      "time_string": "2019-04-24T16:43:49.316Z",
       "time": 1556124229316
     } ,
-    "next_execution": "2019-04-24T01:30:00.000Z", <3>
-    "next_execution_millis": 1556048160000 
+    "last_failure": {                                                    <3>
+      "snapshot_name": "nightly-snap-2019.04.02-lohisb5ith2n8hxacaq3mw",
+      "time_string": "2019-04-02T01:30:00.000Z",
+      "time": 1556042030000,
+      "details": "{\"type\":\"index_not_found_exception\",\"reason\":\"no such index [important]\",\"resource.type\":\"index_or_alias\",\"resource.id\":\"important\",\"index_uuid\":\"_na_\",\"index\":\"important\",\"stack_trace\":\"[important] IndexNotFoundException[no such index [important]]\\n\\tat org.elasticsearch.cluster.metadata.IndexNameExpressionResolver$WildcardExpressionResolver.indexNotFoundException(IndexNameExpressionResolver.java:762)\\n\\tat org.elasticsearch.cluster.metadata.IndexNameExpressionResolver$WildcardExpressionResolver.innerResolve(IndexNameExpressionResolver.java:714)\\n\\tat org.elasticsearch.cluster.metadata.IndexNameExpressionResolver$WildcardExpressionResolver.resolve(IndexNameExpressionResolver.java:670)\\n\\tat org.elasticsearch.cluster.metadata.IndexNameExpressionResolver.concreteIndices(IndexNameExpressionResolver.java:163)\\n\\tat org.elasticsearch.cluster.metadata.IndexNameExpressionResolver.concreteIndexNames(IndexNameExpressionResolver.java:142)\\n\\tat org.elasticsearch.cluster.metadata.IndexNameExpressionResolver.concreteIndexNames(IndexNameExpressionResolver.java:102)\\n\\tat org.elasticsearch.snapshots.SnapshotsService$1.execute(SnapshotsService.java:280)\\n\\tat org.elasticsearch.cluster.ClusterStateUpdateTask.execute(ClusterStateUpdateTask.java:47)\\n\\tat org.elasticsearch.cluster.service.MasterService.executeTasks(MasterService.java:687)\\n\\tat org.elasticsearch.cluster.service.MasterService.calculateTaskOutputs(MasterService.java:310)\\n\\tat org.elasticsearch.cluster.service.MasterService.runTasks(MasterService.java:210)\\n\\tat org.elasticsearch.cluster.service.MasterService$Batcher.run(MasterService.java:142)\\n\\tat org.elasticsearch.cluster.service.TaskBatcher.runIfNotProcessed(TaskBatcher.java:150)\\n\\tat org.elasticsearch.cluster.service.TaskBatcher$BatchedTask.run(TaskBatcher.java:188)\\n\\tat org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingRunnable.run(ThreadContext.java:688)\\n\\tat org.elasticsearch.common.util.concurrent.PrioritizedEsThreadPoolExecutor$TieBreakingPrioritizedRunnable.runAndClean(PrioritizedEsThreadPoolExecutor.java:252)\\n\\tat org.elasticsearch.common.util.concurrent.PrioritizedEsThreadPoolExecutor$TieBreakingPrioritizedRunnable.run(PrioritizedEsThreadPoolExecutor.java:215)\\n\\tat java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)\\n\\tat java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)\\n\\tat java.base/java.lang.Thread.run(Thread.java:834)\\n\"}"
+    } ,
+    "next_execution": "2019-04-24T01:30:00.000Z",                        <4>
+    "next_execution_millis": 1556048160000
   }
 }
 --------------------------------------------------
 // TESTRESPONSE[skip:the presence of last_failure and last_success is asynchronous and will be present for users, but is untestable]
 
-<1> The name of the last snapshot that was succesfully initiated by the policy
-<2> When the snapshot was initiated
-<3> When the policy will initiate the next snapshot
-
+<1> Information about the last time the policy successfully initated a snapshot
+<2> The name of the snapshot that was successfully initiated
+<3> Unformation about the last time the policy failed to initiate a snapshot
+<4> The next time the policy will execute