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Diffstat (limited to 'doc/administration/gitaly/index.md')
| -rw-r--r-- | doc/administration/gitaly/index.md | 38 |
1 files changed, 26 insertions, 12 deletions
diff --git a/doc/administration/gitaly/index.md b/doc/administration/gitaly/index.md index c689530e12c..f99bbf21840 100644 --- a/doc/administration/gitaly/index.md +++ b/doc/administration/gitaly/index.md @@ -189,8 +189,7 @@ The availability objectives for Gitaly clusters assuming a single node failure a Writes are replicated asynchronously. Any writes that have not been replicated to the newly promoted primary are lost. - [Strong consistency](#strong-consistency) can be used to avoid loss in some - circumstances. + [Strong consistency](#strong-consistency) prevents loss in some circumstances. - **Recovery Time Objective (RTO):** Less than 10 seconds. Outages are detected by a health check run by each Praefect node every @@ -284,8 +283,7 @@ Gitaly Cluster provides the following features: - [Replication factor](#replication-factor) of repositories for increased redundancy. - [Automatic failover](praefect.md#automatic-failover-and-primary-election-strategies) from the primary Gitaly node to secondary Gitaly nodes. -- Reporting of possible [data loss](praefect.md#check-for-data-loss) if replication queue is - non-empty. +- Reporting of possible [data loss](recovery.md#check-for-data-loss) if replication queue isn't empty. Follow the [Gitaly Cluster epic](https://gitlab.com/groups/gitlab-org/-/epics/1489) for improvements including [horizontally distributing reads](https://gitlab.com/groups/gitlab-org/-/epics/2013). @@ -323,18 +321,26 @@ You can [monitor distribution of reads](#monitor-gitaly-cluster) using Prometheu > - In GitLab 13.3, disabled unless primary-wins voting strategy is disabled. > - From GitLab 13.4, enabled by default. > - From GitLab 13.5, you must use Git v2.28.0 or higher on Gitaly nodes to enable strong consistency. -> - From GitLab 13.6, primary-wins voting strategy and `gitaly_reference_transactions_primary_wins` feature flag were removed from the source code. +> - From GitLab 13.6, primary-wins voting strategy and the `gitaly_reference_transactions_primary_wins` feature flag was removed. +> - From GitLab 14.0, [Gitaly Cluster only supports strong consistency](https://gitlab.com/gitlab-org/gitaly/-/merge_requests/3575), and the `gitaly_reference_transactions` feature flag was removed. -By default, Gitaly Cluster guarantees eventual consistency by replicating all writes to secondary -Gitaly nodes after the write to the primary Gitaly node has happened. +Gitaly Cluster provides strong consistency by writing changes synchronously to all healthy, up-to-date replicas. If a +replica is outdated or unhealthy at the time of the transaction, the write is asynchronously replicated to it. -Praefect can instead provide strong consistency by creating a transaction and writing changes to all -Gitaly nodes at once. +If strong consistency is unavailable, Gitaly Cluster guarantees eventual consistency. In this case. Gitaly Cluster +replicates all writes to secondary Gitaly nodes after the write to the primary Gitaly node has occurred. -If enabled, transactions are only available for a subset of RPCs. For more information, see the -[strong consistency epic](https://gitlab.com/groups/gitlab-org/-/epics/1189). +Strong consistency: -For configuration information, see [Configure strong consistency](praefect.md#configure-strong-consistency). +- Is the primary replication method in GitLab 14.0 and later. A subset of operations still use replication jobs + (eventual consistency) instead of strong consistency. Refer to the + [strong consistency epic](https://gitlab.com/groups/gitlab-org/-/epics/1189) for more information. +- Must be configured in GitLab versions 13.1 to 13.12. For configuration information, refer to either: + - Documentation on your GitLab instance at `/help`. + - The [13.12 documentation](https://docs.gitlab.com/13.12/ee/administration/gitaly/praefect.html#strong-consistency). +- Is unavailable in GitLab 13.0 and earlier. + +For more information on monitoring strong consistency, see the Gitaly Cluster [Prometheus metrics documentation](#monitor-gitaly-cluster). #### Replication factor @@ -368,6 +374,10 @@ WARNING: Some [known database inconsistency issues](#known-issues) exist in Gitaly Cluster. We recommend you remain on your current service for now. +NOTE: +GitLab requires a `default` repository storage to be configured. +[Read more about this limitation](configure_gitaly.md#gitlab-requires-a-default-repository-storage). + ### Migrate off Gitaly Cluster If you have repositories stored on a Gitaly Cluster, but you'd like to migrate @@ -513,6 +523,10 @@ To monitor [strong consistency](#strong-consistency), you can use the following You can also monitor the [Praefect logs](../logs.md#praefect-logs). +## Recover from failure + +Gitaly Cluster can [recover from certain types of failure](recovery.md). + ## Do not bypass Gitaly GitLab doesn't advise directly accessing Gitaly repositories stored on disk with a Git client, |