Server cluster - Revision history

Tim@horizoneducationnetwork.org: clean up, typos fixed: eg → e.g.

2023-07-06T14:45:55Z

clean up, typos fixed: eg → e.g.

← Older revision		Revision as of 14:45, 6 July 2023
Line 103:		Line 103:
	#Use one big central memcached server for all shared caches that support it.		#Use one big central memcached server for all shared caches that support it.
	#Use local memcached instances on cluster nodes for local caches that support it.		#Use local memcached instances on cluster nodes for local caches that support it.
	#Store user sessions in one shared server eg Redis. (See [[~~Session_handling~~]] for details)		#Store user sessions in one shared server e.g. Redis. (See [[Session handling]] for details)
	#Use fast local directory for dirroot on each cluster node.		#Use fast local directory for dirroot on each cluster node.
	#Use dynamic cluster node management.		#Use dynamic cluster node management.

Brendanheywood: $CFG->alternative_component_cache

2021-06-23T12:08:38Z

$CFG->alternative_component_cache

← Older revision		Revision as of 12:08, 23 June 2021
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	Server clusters MUST use shared filesystem for backuptempdir! This directory gets very large and fast bursts of IO but files do not generally live here for any length of time. They are write heavy and do not have much contention.		Server clusters MUST use shared filesystem for backuptempdir! This directory gets very large and fast bursts of IO but files do not generally live here for any length of time. They are write heavy and do not have much contention.

			===$CFG->alternative_component_cache===

			This is used to cache a very low level representation of the components which Moodle uses. Because it is so low level it is before other higher level API's are available. It is always loaded on every request so putting this onto local disk is much better.

			Typically the $CFG->alternative_component_cache = '/local/cache/dir/core_component.php' would point to local node cache directory.

			NOTE: Before upgrade the administrator MUST have to manually execute following on each node:

			<code>
			$ php admin/cli/alternative_component_cache.php --rebuild
			</code>

			Alternatively you could put the cache file directly into dirroot and distribute it together with new PHP source files. Yet another possibility would be to purge all local caches on all nodes before upgrade or simply change the script name in config.php on all nodes before upgrade. Or this could be built into new containers as part of your CI / CD deployment.

			''Implemented in Moodle 2.6, see MDL-40475.''

	==Performance recommendations==		==Performance recommendations==

Brendanheywood: /* $CFG->backuptempdir */

2021-03-15T22:53:31Z

$CFG->backuptempdir

← Older revision		Revision as of 22:53, 15 March 2021
Line 76:		Line 76:

	By default this is created inside /tmp or whatever sys_get_temp_dir() returns and is generally already local disk and not shared with other nodes. This directory holds temporary folders and files which only exist for the duration of a single http request. If you do change this use local fast filesystem on each cluster node.		By default this is created inside /tmp or whatever sys_get_temp_dir() returns and is generally already local disk and not shared with other nodes. This directory holds temporary folders and files which only exist for the duration of a single http request. If you do change this use local fast filesystem on each cluster node.

			===$CFG->backuptempdir===

			Server clusters MUST use shared filesystem for backuptempdir! This directory gets very large and fast bursts of IO but files do not generally live here for any length of time. They are write heavy and do not have much contention.

	==Performance recommendations==		==Performance recommendations==

Brendanheywood: /* $CFG->alternative_file_system_class */

2021-02-08T22:58:52Z

$CFG->alternative_file_system_class

← Older revision		Revision as of 22:58, 8 February 2021
Line 57:		Line 57:
	https://github.com/catalyst/moodle-tool_objectfs/		https://github.com/catalyst/moodle-tool_objectfs/

	NOTE: Even if you use an alternate filesystem you MUST still have a shared $CFG->dataroot.		NOTE: Even if you use an alternate filesystem you '''MUST''' still have a shared $CFG->dataroot.

	===$CFG->tempdir===		===$CFG->tempdir===

Brendanheywood: /* $CFG->dataroot */

2021-02-08T22:46:26Z

$CFG->dataroot

← Older revision		Revision as of 22:46, 8 February 2021
Line 46:		Line 46:

	Locking support is not required, if any code tries to use file locks in dataroot outside of cachedir or muc directory it is a bug.		Locking support is not required, if any code tries to use file locks in dataroot outside of cachedir or muc directory it is a bug.


	===$CFG->alternative_file_system_class===		===$CFG->alternative_file_system_class===

Brendanheywood: $CFG->alternative_file_system_class

2021-02-08T22:46:11Z

$CFG->alternative_file_system_class

← Older revision		Revision as of 22:46, 8 February 2021
Line 46:		Line 46:

	Locking support is not required, if any code tries to use file locks in dataroot outside of cachedir or muc directory it is a bug.		Locking support is not required, if any code tries to use file locks in dataroot outside of cachedir or muc directory it is a bug.


			===$CFG->alternative_file_system_class===

			By default all uploaded content files are de-duplicated are stored inside [$CFG->dataroot]/filedir. But you can replace this is an alternative file store, like a cloud store such as AWS S3.

			<code php>
			$CFG->alternative_file_system_class = '\tool_objectfs\s3_file_system';
			</code>

			https://github.com/catalyst/moodle-tool_objectfs/

			NOTE: Even if you use an alternate filesystem you MUST still have a shared $CFG->dataroot.

	===$CFG->tempdir===		===$CFG->tempdir===

Brendanheywood: /* Performance recommendations */

2021-02-08T22:22:45Z

Performance recommendations

← Older revision		Revision as of 22:22, 8 February 2021
Line 71:		Line 71:
	#Use one big central memcached server for all shared caches that support it.		#Use one big central memcached server for all shared caches that support it.
	#Use local memcached instances on cluster nodes for local caches that support it.		#Use local memcached instances on cluster nodes for local caches that support it.
	#Store user sessions in one shared ~~memcached~~ server. (See [[Session_handling]] for details)		#Store user sessions in one shared server eg Redis. (See [[Session_handling]] for details)
	#Use fast local directory for dirroot on each cluster node.		#Use fast local directory for dirroot on each cluster node.
	#Use dynamic cluster node management.		#Use dynamic cluster node management.

Brendanheywood: /* $CFG->localcachedir */

2021-02-08T22:21:30Z

$CFG->localcachedir

← Older revision		Revision as of 22:21, 8 February 2021
Line 58:		Line 58:

	The difference from $CFG->cachedir is that the directory does not have to be shared by all cluster nodes, the file contents do not change. Use local fast filesystem on each cluster node.		The difference from $CFG->cachedir is that the directory does not have to be shared by all cluster nodes, the file contents do not change. Use local fast filesystem on each cluster node.

			The nature of this path is very slow moving files that stay for a long time and are written once and never overwritten.

			===$CFG->localrequestdir===

			By default this is created inside /tmp or whatever sys_get_temp_dir() returns and is generally already local disk and not shared with other nodes. This directory holds temporary folders and files which only exist for the duration of a single http request. If you do change this use local fast filesystem on each cluster node.

	==Performance recommendations==		==Performance recommendations==

Nadavkav: /* See also */

2019-08-31T11:49:14Z

Nadavkav: /* Requirements */

2019-08-31T11:34:42Z

Requirements

← Older revision		Revision as of 11:34, 31 August 2019
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	* load balancer - for example Nginx		* load balancer - for example Nginx
	* cluster nodes - web servers		* cluster nodes - web servers
	* Memcached server for shared caches		* Redis (or Memcached) server for shared MUC caches

	Note: this guide is not intended for Windows OS or any other Microsoft technologies.		Note: this guide is not intended for Windows OS or any other Microsoft technologies.

← Older revision		Revision as of 11:49, 31 August 2019
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	*Hardware and performance forum thread [https://moodle.org/mod/forum/discuss.php?d=251547https://moodle.org/mod/forum/discuss.php?d=251547]		*Hardware and performance forum thread [https://moodle.org/mod/forum/discuss.php?d=251547https://moodle.org/mod/forum/discuss.php?d=251547]
	*How to Cluster Moodle on Multiple Servers for High Availability and Scalability [http://www.severalnines.com/blog/clustering-moodle-multiple-servers-high-availability-scalability]		*How to Cluster Moodle on Multiple Servers for High Availability and Scalability [http://www.severalnines.com/blog/clustering-moodle-multiple-servers-high-availability-scalability]
			* PHP session cache in a cluster
			** https://www.digitalocean.com/community/tutorials/how-to-set-up-a-redis-server-as-a-session-handler-for-php-on-ubuntu-14-04
			** https://inchoo.net/magento/programming-magento/session-storage-php