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diff --git a/doc/administration/gitaly/faq.md b/doc/administration/gitaly/faq.md new file mode 100644 index 00000000000..98a90925d32 --- /dev/null +++ b/doc/administration/gitaly/faq.md @@ -0,0 +1,90 @@ +--- +stage: Create +group: Gitaly +info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments +type: reference +--- + +# Frequently asked questions **(FREE SELF)** + +The following are answers to frequently asked questions about Gitaly and Gitaly Cluster. + +## How does Gitaly Cluster compare to Geo? + +Gitaly Cluster and [Geo](../geo/index.md) both provide redundancy. However the redundancy of: + +- Gitaly Cluster provides fault tolerance for data storage and is invisible to the user. Users are + not aware when Gitaly Cluster is used. +- Geo provides [replication](../geo/index.md) and [disaster recovery](../geo/disaster_recovery/index.md) for + an entire instance of GitLab. Users know when they are using Geo for + [replication](../geo/index.md). Geo [replicates multiple data types](../geo/replication/datatypes.md#limitations-on-replicationverification), + including Git data. + +The following table outlines the major differences between Gitaly Cluster and Geo: + +| Tool | Nodes | Locations | Latency tolerance | Failover | Consistency | Provides redundancy for | +|:---------------|:---------|:----------|:-------------------|:----------------------------------------------------------------------------|:-----------------------------------------|:------------------------| +| Gitaly Cluster | Multiple | Single | Approximately 1 ms | [Automatic](praefect.md#automatic-failover-and-primary-election-strategies) | [Strong](praefect.md#strong-consistency) | Data storage in Git | +| Geo | Multiple | Multiple | Up to one minute | [Manual](../geo/disaster_recovery/index.md) | Eventual | Entire GitLab instance | + +For more information, see: + +- Geo [use cases](../geo/index.md#use-cases). +- Geo [architecture](../geo/index.md#architecture). + +## Are there instructions for migrating to Gitaly Cluster? + +Yes! For more information, see [Migrate to Gitaly Cluster](praefect.md#migrate-to-gitaly-cluster). + +## What are some repository storage recommendations? + +The size of the required storage can vary between instances and depends on the set +[replication factor](praefect.md#replication-factor). You might want to include implementing +repository storage redundancy. + +For a replication factor: + +- Of `1`: NFS, Gitaly, and Gitaly Cluster have roughly the same storage requirements. +- More than `1`: The amount of required storage is `used space * replication factor`. `used space` + should include any planned future growth. + +## What are some Praefect database storage requirements? + +The requirements are relatively low because the database contains only metadata of: + +- Where repositories are located. +- Some queued work. + +It depends on the number of repositories, but a useful minimum is 5-10 GB, similar to the main +GitLab application database. + +## Can the GitLab application database and the Praefect database be on the same servers? + +Yes, however Praefect should have it's own database server when using Omnibus GitLab PostgreSQL. If +there is a failover, Praefect isn't aware and starts to fail as the database it's trying to use would +either: + +- Be unavailable. +- In read-only mode. + +A future solution may allow for Praefect and Omnibus GitLab databases on the same PostgreSQL server. +For more information, see the relevant: + +- [Omnibus GitLab issue](https://gitlab.com/gitlab-org/omnibus-gitlab/-/issues/5919). +- [Gitaly issue](https://gitlab.com/gitlab-org/gitaly/-/issues/3398). + +## Is PgBouncer required for the Praefect database? + +No, because the number of connections Praefect makes is low. You can use the same PgBouncer instance +for both the GitLab application database and the Praefect database if you wish. + +## Are there any special considerations for Gitaly Cluster when PostgreSQL is upgraded? + +There are no special requirements. Gitaly Cluster requires PostgreSQL version 11 or later. + +## Praefect database tables are empty? + +These tables are created per the [specific configuration section](praefect.md#postgresql). + +If you find you have an empty Praefect database table, see the +[relevant troubleshooting section](index.md#relation-does-not-exist-errors). |