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From jmhs...@apache.org
Subject [38/50] [abbrv] hbase git commit: HBASE-13699 Expand documentation about quotas and other load balancing mechanisms
Date Wed, 20 May 2015 15:25:51 GMT
HBASE-13699 Expand documentation about quotas and other load balancing mechanisms


Project: http://git-wip-us.apache.org/repos/asf/hbase/repo
Commit: http://git-wip-us.apache.org/repos/asf/hbase/commit/a93353e8
Tree: http://git-wip-us.apache.org/repos/asf/hbase/tree/a93353e8
Diff: http://git-wip-us.apache.org/repos/asf/hbase/diff/a93353e8

Branch: refs/heads/hbase-11339
Commit: a93353e83ce514b48700b3f5ba16f8a41204e1fa
Parents: 88f0f42
Author: Misty Stanley-Jones <mstanleyjones@cloudera.com>
Authored: Fri May 15 15:53:42 2015 -0700
Committer: Misty Stanley-Jones <mstanleyjones@cloudera.com>
Committed: Fri May 15 17:03:47 2015 -0700

----------------------------------------------------------------------
 src/main/asciidoc/_chapters/ops_mgt.adoc | 378 ++++++++++----------------
 1 file changed, 141 insertions(+), 237 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/hbase/blob/a93353e8/src/main/asciidoc/_chapters/ops_mgt.adoc
----------------------------------------------------------------------
diff --git a/src/main/asciidoc/_chapters/ops_mgt.adoc b/src/main/asciidoc/_chapters/ops_mgt.adoc
index 82f093e..3c4a73b 100644
--- a/src/main/asciidoc/_chapters/ops_mgt.adoc
+++ b/src/main/asciidoc/_chapters/ops_mgt.adoc
@@ -1311,13 +1311,13 @@ list_peers:: list all replication relationships known by this cluster
 enable_peer <ID>::
   Enable a previously-disabled replication relationship
 disable_peer <ID>::
-  Disable a replication relationship. HBase will no longer send edits to that peer cluster,
but it still keeps track of all the new WALs that it will need to replicate if and when it
is re-enabled. 
+  Disable a replication relationship. HBase will no longer send edits to that peer cluster,
but it still keeps track of all the new WALs that it will need to replicate if and when it
is re-enabled.
 remove_peer <ID>::
   Disable and remove a replication relationship. HBase will no longer send edits to that
peer cluster or keep track of WALs.
 enable_table_replication <TABLE_NAME>::
-  Enable the table replication switch for all it's column families. If the table is not found
in the destination cluster then it will create one with the same name and column families.

+  Enable the table replication switch for all it's column families. If the table is not found
in the destination cluster then it will create one with the same name and column families.
 disable_table_replication <TABLE_NAME>::
-  Disable the table replication switch for all it's column families. 
+  Disable the table replication switch for all it's column families.
 
 === Verifying Replicated Data
 
@@ -1609,282 +1609,186 @@ You can use the HBase Shell command `status 'replication'` to monitor
the replic
 * `status 'replication', 'source'` -- prints the status for each replication source, sorted
by hostname.
 * `status 'replication', 'sink'` -- prints the status for each replication sink, sorted by
hostname.
 
+== Running Multiple Workloads On a Single Cluster
 
-[[quota]]
-== HBase Quota
-
-When a work load increases on a cluster due to multiple users or user requests, the system
needs to prioritize the users or the user requests for a smooth operation. 
-This is handled by the HBase quota feature. The quota allows the admin to limit the number
of tables, regions, or request in a system.
-
-The HBase features three types of quotas, they are:
-
-. Namespace Quota
-. Request Number Quota
-. Request Size Quota
-
-[[enabling.quota]]
-=== Enabling Quota
-
-By default the quota function is disabled. To enable the quota, change the value of parameter
`hbase.quota.enabled` to `true` in _hbase-site.xml_ file for all HMaster and HRegionServer
machines.
-
-[[quota.cache.refresh]]
-=== Quota Cache Refresh Configuration
-By default quota setting cache refresh time period `'hbase.quota.refresh.period'` is set
to 5*60000(5 mins). Which means a user has to wait for maximum of 5 mins to get his quota
settings updated.
-
-[[namespace.quota]]
-=== Namespace Quota	
-
-Namespace quota reserves the number of tables or regions allowed in a Namespace. 
-
-Following are the namespace quota:
-
-* Number of tables allowed in a namespace.
-
-[cols="1,1", options="header"]
-|===
-| Example
-| Command Description
-
-| create_namespace 'namespace_name', {'hbase.namespace.quota.maxtables'=>'5'}
-| Creates a namespace with the maximum table quota.
-
-| describe_namespace 'namespace_name'
-| Displays the quota information on the namespace.
-
-| alter_namespace 'namespace_name ', {METHOD => 'set', 'hbase.namespace.quota.maxtables'=>'8'}
-| Modifies the existing namespace and sets the maximum table quota.
-
-| alter_namespace 'namespace_name ', {METHOD => 'unset', NAME=> 'hbase.namespace.quota.maxtables'}
-| Removes the maximum table quota set on a namespace.
-
-|===
-
-* Number of regions allowed in a namespace.
-
-[cols="1,1", options="header"]
-|===
-| Example
-| Command Description
-
-| create_namespace 'namespace_name', {'hbase.namespace.quota.maxregions'=>'10'}	
-| Creates a namespace with the maximum regions quota.
-
-| describe_namespace 'namespace_name '	
-| Displays the quota information on the namespace.
-
-| alter_namespace 'namespace_name ', {METHOD => 'set', 'hbase.namespace.quota.maxregions'=>'20'}
-| Modifies the existing namespace and sets the maximum regions quota.
-
-| alter_namespace 'namespace_name ', {METHOD => 'unset', NAME=> 'hbase.namespace.quota.maxregions'}
-| Removes the maximum regions quota set on a namespace.
-
-|===
-
-[[number.quota]]
-=== Request Number Quota
-
-Request Number Quota reserves the number of requests that is allowed to execute on a particular
table or namespace in any given time by a user or users with similar name. 
-
-[NOTE]
-====
-The Request Number Quota uses time units in the command. 
-The valid time units are sec, min, hour, and day. 
-====
-
-Following are the five types of request number quota:
-
-* Number of requests a user can execute in a given time.
-
-[cols="1,1", options="header"]
-|===
-| Example
-| Command Description
-
-| set_quota TYPE => THROTTLE, USER => 'user_name', LIMIT => '10req/sec'
-| Sets 10req/sec quota for a specified user.
-
-| list_quotas USER => 'user_name'
-| Displays the quota information of the specified user.
-
-| set_quota TYPE => THROTTLE, USER => ' user_name ', LIMIT => NONE
-| Removes the quota of the specified user.
-
-|===
-
-* Number of requests a user can execute on a given table in a given time.
-
-[cols="1,1", options="header"]
-|===
-| Example
-| Command Description
-
-| set_quota TYPE => THROTTLE, USER => ' user_name ', TABLE => 't1', LIMIT =>
'10req/sec'
-| Sets 10req/sec quota on a particular table for a specified user.
-
-| list_quotas USER => 'user_name', TABLE => 't1'
-| Displays the quota information of the specified user on a particular table.
-
-| set_quota TYPE => THROTTLE, USER => 'u1', TABLE => 't1', LIMIT => NONE
-| Removes the quota on a particular table for a specified user.
-
-|===
-
-* Number of requests a user can execute on a given namespace in a given time.
-
-[cols="1,1", options="header"]
-|===
-| Example
-| Command Description
-
-| set_quota TYPE => THROTTLE, USER => ' user_name ', NAMESPACE => 'ns1', LIMIT =>
'10req/sec'
-| Sets 10req/sec quota on a particular namespace for a specified user.
-
-| list_quotas USER => 'user_name', NAMESPACE => 'ns.*'
-| Displays the quota information of the specified user on a particular namespace.
-
-| set_quota TYPE => THROTTLE, USER => 'u1', NAMESPACE => 'ns1', LIMIT => NONE
-| Removes the quota on a particular namespace for a specified user.
+HBase provides the following mechanisms for managing the performance of a cluster
+handling multiple workloads:
+. <<quota>>
+. <<request-queues>>
+. <<multiple-typed-queues>>
 
-|===
-
-* Number of requests that can be allowed on a table in a given time.
-
-[cols="1,1", options="header"]
-|===
-| Example
-| Command Description
-
-| set_quota TYPE => THROTTLE, TABLE => 't1, LIMIT => '10req/sec'
-| Sets 10req/sec quota on a particular table.
-
-| list_quotas TABLE => 't1'
-| Displays the quota information on a particular table.
+[[quota]]
+=== Quotas
+HBASE-11598 introduces quotas, which allow you to throttle requests based on
+the following limits:
 
-| set_quota TYPE => THROTTLE, TABLE => 't1', LIMIT => NONE
-| Removes the quota on a particular table.
+. <<request-quotas,The number or size of requests in a given timeframe>>
+. <<namespace-quotas,The number of tables allowed in a namespace>>
 
-|===
+These limits can be enforced for a specified user, table, or namespace.
 
-* Number of requests that can be allowed on a namespace in a given time.
+.Enabling Quotas
 
-[cols="1,1", options="header"]
-|===
-| Example
-| Command Description
+Quotas are disabled by default. To enable the feature, set the `hbase.quota.enabled`
+property to `true` in _hbase-site.xml_ file for all cluster nodes.
 
-| set_quota TYPE => THROTTLE, NAMESPACE => 'ns1', LIMIT => '10req/sec'
-| Sets 10req/sec quota on a particular namespace.
+.General Quota Syntax
+. Timeframes  can be expressed in the following units: `sec`, `min`, `hour`, `day`
+. Request sizes can be expressed in the following units: `B` (bytes), `K` (kilobytes),
+`M` (megabytes), `G` (gigabytes), `T` (terabytes), `P` (petabytes)
+. Numbers of requests are expressed as an integer followed by the string `req`
+. Limits relating to time are expressed as req/time or size/time. For instance `10req/day`
+or `100P/hour`.
+. Numbers of tables or regions are expressed as integers.
 
-| list_quotas NAMESPACE => 'ns1'
-| Displays the quota information on a particular namespace.
+[[request-quotas]]
+.Setting Request Quotas
+You can set quota rules ahead of time, or you can change the throttle at runtime. The change
+will propagate after the quota refresh period has expired. This expiration period
+defaults to 5 minutes. To change it, modify the `hbase.quota.refresh.period` property
+in `hbase-site.xml`. This property is expressed in milliseconds and defaults to `300000`.
 
-| set_quota TYPE => THROTTLE, NAMESPACE => 'ns1', LIMIT => NONE
-| Removes the quota on a particular namespace.
-
-|===
+----
+# Limit user u1 to 10 requests per second
+hbase> set_quota TYPE => THROTTLE, USER => 'u1', LIMIT => '10req/sec'
 
-[[size.quota]]
-=== Request Size Quota
+# Limit user u1 to 10 M per day everywhere
+hbase> set_quota TYPE => THROTTLE, USER => 'u1', LIMIT => '10M/day'
 
-Request size quota reserves the size of the requests that is allowed to execute on a particular
table or a namespace in any given time by a user or users with similar name.  
+# Limit user u1 to 5k per minute on table t2
+hbase> set_quota TYPE => THROTTLE, USER => 'u1', TABLE => 't2', LIMIT => '5K/min'
 
-[NOTE]
-====
-The Request Size Quota uses time and size unit in the command. 
-The valid size units are B(byte), K(kilobyte), M(megabyte), G(gigabyte), T(terabyte), and
P(petabyte).
-====
+# Remove an existing limit from user u1 on namespace ns2
+hbase> set_quota TYPE => THROTTLE, USER => 'u1', NAMESPACE => 'ns2', LIMIT =>
NONE
 
-Following are the five types of request size quota:
+# Limit all users to 10 requests per hour on namespace ns1
+hbase> set_quota TYPE => THROTTLE, NAMESPACE => 'ns1', LIMIT => '10req/shour'
 
-* Size of requests a user can execute in a given time.
+# Limit all users to 10 T per hour on table t1
+hbase> set_quota TYPE => THROTTLE, TABLE => 't1', LIMIT => '10T/hour'
 
-[cols="1,1", options="header"]
-|===
-| Example
-| Command Description
+# Remove all existing limits from user u1
+hbase> set_quota TYPE => THROTTLE, USER => 'u1', LIMIT => NONE
 
-| set_quota TYPE => THROTTLE, USER => 'user_name', LIMIT => '5K/min'
-| Sets 5k/sec quota for a specified user.
+# List all quotas for user u1 in namespace ns2
+hbase> list_quotas USER => 'u1, NAMESPACE => 'ns2'
 
-| list_quotas USER => 'user_name'
-| Displays the quota information of the specified user.
+# List all quotas for namespace ns2
+hbase> list_quotas NAMESPACE => 'ns2'
 
-| set_quota TYPE => THROTTLE, USER => ' user_name ', LIMIT => NONE
-| Removes the quota of the specified user.
+# List all quotas for table t1
+hbase> list_quotas TABLE => 't1'
 
-|===
-
-* Size of requests a user can execute on a given table in a given time.
+# list all quotas
+hbase> list_quotas
+----
 
-[cols="1,1", options="header"]
-|===
-| Example
-| Command Description
+You can also place a global limit and exclude a user or a table from the limit by applying
the
+`GLOBAL_BYPASS` property.
+----
+hbase> set_quota NAMESPACE => 'ns1', LIMIT => '100req/min'               # a per-namespace
request limit
+hbase> set_quota USER => 'u1', GLOBAL_BYPASS => true                     # user
u1 is not affected by the limit
+----
 
-| set_quota TYPE => THROTTLE, USER => 'u1', TABLE => 'table_name', LIMIT => '5K/min'
-| Sets 5k/sec quota on a particular table for a specified user.
+[[namespace_quotas]]
+.Setting Namespace Quotas
 
-| list_quotas USER => 'bob.*', TABLE => 't1'
-| Displays the quota information of the specified user on a particular table.
+You can specify the maximum number of tables or regions allowed in a given namespace, either
+when you create the namespace or by altering an existing namespace, by setting the
+`hbase.namespace.quota.maxtables property`  on the namespace.
 
-| set_quota TYPE => THROTTLE, USER => 'u1', TABLE => 't1', LIMIT => NONE
-| Removes the quota on a particular table for a specified user.
+.Limiting Tables Per Namespace
+----
+# Create a namespace with a max of 5 tables
+hbase> create_namespace 'ns1', {'hbase.namespace.quota.maxtables'=>'5'}
 
-|===
+# Alter an existing namespace to have a max of 8 tables
+hbase> alter_namespace 'ns2', {METHOD => 'set', 'hbase.namespace.quota.maxtables'=>'8'}
 
-* Size of requests a user can execute on a given namespace in a given time.
+# Show quota information for a namespace
+hbase> describe_namespace 'ns2'
 
-[cols="1,1", options="header"]
-|===
-| Example
-| Command Description
+# Alter an existing namespace to remove a quota
+hbase> alter_namespace 'ns2', {METHOD => 'unset', NAME=>'hbase.namespace.quota.maxtables'}
+----
 
-| set_quota TYPE => THROTTLE, USER => 'u1', NAMESPACE => 'ns1', LIMIT => '5K/min'
-| Sets 5k/sec quota on a particular namespace for a specified user.
+.Limiting Regions Per Namespace
+----
+# Create a namespace with a max of 10 regions
+hbase> create_namespace 'ns1', {'hbase.namespace.quota.maxregions'=>'10'
 
-| list_quotas USER => 'bob.*', NAMESPACE => 'ns.*'
-| Displays the quota information of the specified user on a particular namespace.
+# Show quota information for a namespace
+hbase> describe_namespace 'ns1'
 
-| set_quota TYPE => THROTTLE, USER => 'u1', NAMESPACE => 'ns1', LIMIT => NONE
-| Removes the quota on a particular namespace for a specified user.
+# Alter an existing namespace to have a max of 20 tables
+hbase> alter_namespace 'ns2', {METHOD => 'set', 'hbase.namespace.quota.maxregions'=>'20'}
 
-|===
+# Alter an existing namespace to remove a quota
+hbase> alter_namespace 'ns2', {METHOD => 'unset', NAME=> 'hbase.namespace.quota.maxregions'}
+----
 
-* Size of requests that can be allowed on a table in a given time.
+[[request_queues]]
+=== Request Queues
+If no throttling policy is configured, when the RegionServer receives multiple requests,
+they are now placed into a queue waiting for a free execution slot (HBASE-6721).
+The simplest queue is a FIFO queue, where each request waits for all previous requests in
the queue
+to finish before running. Fast or interactive queries can get stuck behind large requests.
 
-[cols="1,1", options="header"]
-|===
-| Example
-| Command Description
+If you are able to guess how long a request will take, you can reorder requests by
+pushing the long requests to the end of the queue and allowing short requests to preempt
+them. Eventually, you must still execute the large requests and prioritize the new
+requests behind them. The short requests will be newer, so the result is not terrible,
+but still suboptimal compared to a mechanism which allows large requests to be split
+into multiple smaller ones.
 
-| set_quota TYPE => THROTTLE, TABLE => 't1', LIMIT => '5K/min'
-| Sets 5k/sec quota on a particular table.
+HBASE-10993 introduces such a system for deprioritizing long-running scanners. There
+are two types of queues,`fifo` and `deadline`.To configure the type of queue used,
+configure the `hbase.ipc.server.callqueue.type` property in `hbase-site.xml`. There
+is no way to estimate how long each request may take, so de-prioritization only affects
+scans, and is based on the number of “next” calls a scan request has made. An assumption
+is made that when you are doing a full table scan, your job is not likely to be interactive,
+so if there are concurrent requests, you can delay long-running scans up to a limit tunable
by
+setting the `hbase.ipc.server.queue.max.call.delay` property. The slope of the delay is calculated
+by a simple square root of `(numNextCall * weight)` where the weight is
+configurable by setting the `hbase.ipc.server.scan.vtime.weight` property.
 
-| list_quotas TABLE => 'myTable'
-| Displays the quota information on a particular table.
+[[multiple-typed-queues]]
+=== Multiple-Typed Queues
 
-| set_quota TYPE => THROTTLE, TABLE => 't1', LIMIT => NONE
-| Removes the quota on a particular table.
+You can also prioritize or deprioritize different kinds of requests by configuring
+a specified number of dedicated handlers and queues. You can segregate the scan requests
+in a single queue with a single handler, and all the other available queues can service
+short `Get` requests.
 
-|===
+You can adjust the IPC queues and handlers based on the type of workload, using static
+tuning options. This approach is an interim first step that will eventually allow
+you to change the settings at runtime, and to dynamically adjust values based on the load.
 
-* Size of requests that can be allowed on a namespace in a given time.
+.Multiple Queues
 
-[cols="1,1", options="header"]
-|===
-| Example
-| Command Description
+To avoid contention and separate different kinds of requests, configure the
+`hbase.ipc.server.callqueue.handler.factor` property, which allows you to increase the number
of
+queues and control how many handlers can share the same queue., allows admins to increase
the number
+of queues and decide how many handlers share the same queue.
 
-| set_quota TYPE => THROTTLE, NAMESPACE => 'ns1', LIMIT => '5K/min'
-| Sets 5k/sec  quota on a particular namespace.
+Using more queues reduces contention when adding a task to a queue or selecting it
+from a queue. You can even configure one queue per handler. The trade-off is that
+if some queues contain long-running tasks, a handler may need to wait to execute from that
queue
+rather than stealing from another queue which has waiting tasks.
 
-| list_quotas NAMESPACE => 'ns.*'
-| Displays the quota information on a particular namespace.
+.Read and Write Queues
+With multiple queues, you can now divide read and write requests, giving more priority
+(more queues) to one or the other type. Use the `hbase.ipc.server.callqueue.read.ratio`
+property to choose to serve more reads or more writes.
 
-| set_quota TYPE => THROTTLE, NAMESPACE => 'ns1', LIMIT => NONE
-| Removes the quota on a particular namespace.
+.Get and Scan Queues
+Similar to the read/write split, you can split gets and scans by tuning the `hbase.ipc.server.callqueue.scan.ratio`
+property to give more priority to gets or to scans. A scan ratio of `0.1` will give
+more queue/handlers to the incoming gets, which means that more gets can be processed
+at the same time and that fewer scans can be executed at the same time. A value of
+`0.9` will give more queue/handlers to scans, so the number of scans executed will
+increase and the number of gets will decrease.
 
-|===
 
 [[ops.backup]]
 == HBase Backup


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