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Diffstat (limited to 'doc/administration/database_load_balancing.md')
| -rw-r--r-- | doc/administration/database_load_balancing.md | 37 |
1 files changed, 15 insertions, 22 deletions
diff --git a/doc/administration/database_load_balancing.md b/doc/administration/database_load_balancing.md index b6ce6883dd6..0f566fcc114 100644 --- a/doc/administration/database_load_balancing.md +++ b/doc/administration/database_load_balancing.md @@ -1,6 +1,6 @@ # Database Load Balancing **(PREMIUM ONLY)** -> [Introduced][ee-1283] in [GitLab Premium][eep] 9.0. +> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/1283) in [GitLab Premium](https://about.gitlab.com/pricing/) 9.0. Distribute read-only queries among multiple database servers. @@ -11,7 +11,7 @@ multiple computing resources. Load balancing aims to optimize resource use, maximize throughput, minimize response time, and avoid overload of any single resource. Using multiple components with load balancing instead of a single component may increase reliability and availability through redundancy. -[_Wikipedia article_][wikipedia] +[_Wikipedia article_](https://en.wikipedia.org/wiki/Load_balancing_(computing)) When database load balancing is enabled in GitLab, the load is balanced using a simple round-robin algorithm, without any external dependencies such as Redis. @@ -26,9 +26,9 @@ sent to the primary (unless necessary), the primary (`db3`) hardly has any load. ## Requirements -For load balancing to work you will need at least PostgreSQL 9.2 or newer, -[**MySQL is not supported**][db-req]. You also need to make sure that you have -at least 1 secondary in [hot standby][hot-standby] mode. +For load balancing to work you will need at least PostgreSQL 11 or newer, +[**MySQL is not supported**](../install/requirements.md#database). You also need to make sure that you have +at least 1 secondary in [hot standby](https://www.postgresql.org/docs/11/hot-standby.html) mode. Load balancing also requires that the configured hosts **always** point to the primary, even after a database failover. Furthermore, the additional hosts to @@ -78,7 +78,7 @@ the following. This will balance the load between `host1.example.com` and gitlab_rails['db_load_balancing'] = { 'hosts' => ['host1.example.com', 'host2.example.com'] } ``` -1. Save the file and [reconfigure GitLab][] for the changes to take effect. +1. Save the file and [reconfigure GitLab](restart_gitlab.md#omnibus-gitlab-reconfigure) for the changes to take effect. --- @@ -97,11 +97,11 @@ the following. This will balance the load between `host1.example.com` and - host2.example.com ``` -1. Save the file and [restart GitLab][] for the changes to take effect. +1. Save the file and [restart GitLab](restart_gitlab.md#installations-from-source) for the changes to take effect. ## Service Discovery -> [Introduced][ee-5883] in [GitLab Premium][eep] 11.0. +> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/5883) in [GitLab Premium](https://about.gitlab.com/pricing/) 11.0. Service discovery allows GitLab to automatically retrieve a list of secondary databases to use, instead of having to manually specify these in the @@ -161,12 +161,16 @@ When the list of hosts is updated, it might take a while for the old connections to be terminated. The `disconnect_timeout` setting can be used to enforce an upper limit on the time it will take to terminate all old database connections. -Some nameservers (like [Consul][consul-udp]) can return a truncated list of hosts when +Some nameservers (like [Consul](https://www.consul.io/docs/agent/dns.html#udp-based-dns-queries)) can return a truncated list of hosts when queried over UDP. To overcome this issue, you can use TCP for querying by setting `use_tcp` to `true`. ### Forking +NOTE: **Note:** +Starting with GitLab 13.0, Puma is the default web server used in GitLab +all-in-one package based installations as well as GitLab Helm chart deployments. + If you use an application server that forks, such as Unicorn, you _have to_ update your Unicorn configuration to start service discovery _after_ a fork. Failure to do so will lead to service discovery only running in the parent @@ -239,14 +243,14 @@ For example: ## Handling Stale Reads -> [Introduced][ee-3526] in [GitLab Premium][eep] 10.3. +> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/3526) in [GitLab Premium](https://about.gitlab.com/pricing/) 10.3. To prevent reading from an outdated secondary the load balancer will check if it is in sync with the primary. If the data is determined to be recent enough the secondary can be used, otherwise it will be ignored. To reduce the overhead of these checks we only perform these checks at certain intervals. -There are three configuration options that influence this behaviour: +There are three configuration options that influence this behavior: | Option | Description | Default | |------------------------------|----------------------------------------------------------------------------------------------------------------|------------| @@ -270,14 +274,3 @@ production: max_replication_lag_time: 30 replica_check_interval: 30 ``` - -[hot-standby]: https://www.postgresql.org/docs/9.6/hot-standby.html -[ee-1283]: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/1283 -[eep]: https://about.gitlab.com/pricing/ -[reconfigure gitlab]: restart_gitlab.md#omnibus-gitlab-reconfigure "How to reconfigure Omnibus GitLab" -[restart gitlab]: restart_gitlab.md#installations-from-source "How to restart GitLab" -[wikipedia]: https://en.wikipedia.org/wiki/Load_balancing_(computing) -[db-req]: ../install/requirements.md#database -[ee-3526]: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/3526 -[ee-5883]: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/5883 -[consul-udp]: https://www.consul.io/docs/agent/dns.html#udp-based-dns-queries |