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Commit bb605763 authored by Fiona Neill's avatar Fiona Neill
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Merge branch 'eread/split-out-recovery-information' into 'master' 

Separate recovery information from configuration information

See merge request gitlab-org/gitlab!75591
parents 45f883b4 480d53ff
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doc/administration/gitaly/index.md
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...@@ -283,8 +283,7 @@ Gitaly Cluster provides the following features: ...@@ -283,8 +283,7 @@ Gitaly Cluster provides the following features:
- [Replication factor](#replication-factor) of repositories for increased redundancy. - [Replication factor](#replication-factor) of repositories for increased redundancy.
- [Automatic failover](praefect.md#automatic-failover-and-primary-election-strategies) from the - [Automatic failover](praefect.md#automatic-failover-and-primary-election-strategies) from the
primary Gitaly node to secondary Gitaly nodes. primary Gitaly node to secondary Gitaly nodes.
- Reporting of possible [data loss](praefect.md#check-for-data-loss) if replication queue is - Reporting of possible [data loss](recovery.md#check-for-data-loss) if replication queue isn't empty.
non-empty.
Follow the [Gitaly Cluster epic](https://gitlab.com/groups/gitlab-org/-/epics/1489) for improvements 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). including [horizontally distributing reads](https://gitlab.com/groups/gitlab-org/-/epics/2013).
...@@ -524,6 +523,10 @@ To monitor [strong consistency](#strong-consistency), you can use the following ...@@ -524,6 +523,10 @@ To monitor [strong consistency](#strong-consistency), you can use the following
You can also monitor the [Praefect logs](../logs.md#praefect-logs). 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 ## Do not bypass Gitaly
GitLab doesn't advise directly accessing Gitaly repositories stored on disk with a Git client, GitLab doesn't advise directly accessing Gitaly repositories stored on disk with a Git client,
......
doc/administration/gitaly/praefect.md
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...@@ -1293,481 +1293,3 @@ Migrate to [repository-specific primary nodes](#repository-specific-primary-node ...@@ -1293,481 +1293,3 @@ Migrate to [repository-specific primary nodes](#repository-specific-primary-node
If a sufficient number of health checks fail for the current primary Gitaly node, a new primary is If a sufficient number of health checks fail for the current primary Gitaly node, a new primary is
elected. **Do not use with multiple Praefect nodes!** Using with multiple Praefect nodes is elected. **Do not use with multiple Praefect nodes!** Using with multiple Praefect nodes is
likely to result in a split brain. likely to result in a split brain.
## Primary Node Failure
Gitaly Cluster recovers from a failing primary Gitaly node by promoting a healthy secondary as the
new primary.
In GitLab 14.1 and later, Gitaly Cluster:
- Elects a healthy secondary with a fully up to date copy of the repository as the new primary.
- Repository becomes unavailable if there are no fully up to date copies of it on healthy secondaries.
To minimize data loss in GitLab 13.0 to 14.0, Gitaly Cluster:
- Switches repositories that are outdated on the new primary to [read-only mode](#read-only-mode).
- Elects the secondary with the least unreplicated writes from the primary to be the new
primary. Because there can still be some unreplicated writes,
[data loss can occur](#check-for-data-loss).
### Read-only mode
> - Introduced in GitLab 13.0 as [generally available](https://about.gitlab.com/handbook/product/gitlab-the-product/#generally-available-ga).
> - Between GitLab 13.0 and GitLab 13.2, read-only mode applied to the whole virtual storage and occurred whenever failover occurred.
> - [In GitLab 13.3 and later](https://gitlab.com/gitlab-org/gitaly/-/issues/2862), read-only mode applies on a per-repository basis and only occurs if a new primary is out of date.
new primary. If the failed primary contained unreplicated writes, [data loss can occur](#check-for-data-loss).
> - Removed in GitLab 14.1. Instead, repositories [become unavailable](#unavailable-repositories).
When Gitaly Cluster switches to a new primary in GitLab 13.0 to 14.0, repositories enter
read-only mode if they are out of date. This can happen after failing over to an outdated
secondary. Read-only mode eases data recovery efforts by preventing writes that may conflict
with the unreplicated writes on other nodes.
To enable writes again in GitLab 13.0 to 14.0, an administrator can:
1. [Check](#check-for-data-loss) for data loss.
1. Attempt to [recover](#data-recovery) missing data.
1. Either [enable writes](#enable-writes-or-accept-data-loss) in the virtual storage or
[accept data loss](#enable-writes-or-accept-data-loss) if necessary, depending on the version of
GitLab.
## Retrieve repository metadata
> [Introduced](https://gitlab.com/gitlab-org/gitaly/-/issues/3481) in GitLab 14.6.
Gitaly Cluster maintains a [metadata database](index.md#components) about the repositories stored on the cluster. Use the `praefect metadata` subcommand
to inspect the metadata for troubleshooting.
You can retrieve a repository's metadata by its Praefect-assigned repository ID:
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml metadata -repository-id <repository-id>
```
You can also retrieve a repository's metadata by its virtual storage and relative path:
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml metadata -virtual-storage <virtual-storage> -relative-path <relative-path>
```
### Examples
To retrieve the metadata for a repository with a Praefect-assigned repository ID of 1:
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml metadata -repository-id 1
```
To retrieve the metadata for a repository with virtual storage `default` and relative path `@hashed/b1/7e/b17ef6d19c7a5b1ee83b907c595526dcb1eb06db8227d650d5dda0a9f4ce8cd9.git`:
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml metadata -virtual-storage default -relative-path @hashed/b1/7e/b17ef6d19c7a5b1ee83b907c595526dcb1eb06db8227d650d5dda0a9f4ce8cd9.git
```
Either of these examples retrieve the following metadata for an example repository:
```plaintext
Repository ID: 54771
Virtual Storage: "default"
Relative Path: "@hashed/b1/7e/b17ef6d19c7a5b1ee83b907c595526dcb1eb06db8227d650d5dda0a9f4ce8cd9.git"
Replica Path: "@hashed/b1/7e/b17ef6d19c7a5b1ee83b907c595526dcb1eb06db8227d650d5dda0a9f4ce8cd9.git"
Primary: "gitaly-1"
Generation: 1
Replicas:
- Storage: "gitaly-1"
Assigned: true
Generation: 1, fully up to date
Healthy: true
Valid Primary: true
- Storage: "gitaly-2"
Assigned: true
Generation: 0, behind by 1 changes
Healthy: true
Valid Primary: false
- Storage: "gitaly-3"
Assigned: true
Generation: replica not yet created
Healthy: false
Valid Primary: false
```
### Available metadata
The metadata retrieved by `praefect metadata` includes the fields in the following tables.
| Field | Description |
|:------------------|:-------------------------------------------------------------------------------------------------------------------|
| `Repository ID` | Permanent unique ID assigned to the repository by Praefect. Different to the ID GitLab uses for repositories. |
| `Virtual Storage` | Name of the virtual storage the repository is stored in. |
| `Relative Path` | Repository's path in the virtual storage. |
| `Replica Path` | Where on the Gitaly node's disk the repository's replicas are stored. |
| `Primary` | Current primary of the repository. |
| `Generation` | Used by Praefect to track repository changes. Each write in the repository increments the repository's generation. |
| `Replicas` | A list of replicas that exist or are expected to exist. |
For each replica, the following metadata is available:
| `Replicas` Field | Description |
|:-----------------|:-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `Storage` | Name of the Gitaly storage that contains the replica. |
| `Assigned` | Indicates whether the replica is expected to exist in the storage. Can be `false` if a Gitaly node is removed from the cluster or if the storage contains an extra copy after the repository's replication factor was decreased. |
| `Generation` | Latest confirmed generation of the replica. It indicates:<br><br>- The replica is fully up to date if the generation matches the repository's generation.<br>- The replica is outdated if the replica's generation is less than the repository's generation.<br>- `replica not yet created` if the replica does not yet exist at all on the storage. |
| `Healthy` | Indicates whether the Gitaly node that is hosting this replica is considered healthy by the consensus of Praefect nodes. |
| `Valid Primary` | Indicates whether the replica is fit to serve as the primary node. If the repository's primary is not a valid primary, a failover occurs on the next write to the repository if there is another replica that is a valid primary. A replica is a valid primary if:<br><br>- It is stored on a healthy Gitaly node.<br>- It is fully up to date.<br>- It is not targeted by a pending deletion job from decreasing replication factor.<br>- It is assigned. |
## Unavailable repositories
> - From GitLab 13.0 through 14.0, repositories became read-only if they were outdated on the primary but fully up to date on a healthy secondary. `dataloss` sub-command displays read-only repositories by default through these versions.
> - Since GitLab 14.1, Praefect contains more responsive failover logic which immediately fails over to one of the fully up to date secondaries rather than placing the repository in read-only mode. Since GitLab 14.1, the `dataloss` sub-command displays repositories which are unavailable due to having no fully up to date copies on healthy Gitaly nodes.
A repository is unavailable if all of its up to date replicas are unavailable. Unavailable repositories are
not accessible through Praefect to prevent serving stale data that may break automated tooling.
### Check for data loss
The Praefect `dataloss` subcommand identifies:
- Copies of repositories in GitLab 13.0 to GitLab 14.0 that at are likely to be outdated.
This can help identify potential data loss after a failover.
- Repositories in GitLab 14.1 and later that are unavailable. This helps identify potential
data loss and repositories which are no longer accessible because all of their up-to-date
replicas copies are unavailable.
The following parameters are available:
- `-virtual-storage` that specifies which virtual storage to check. Because they might require
an administrator to intervene, the default behavior is to display:
- In GitLab 13.0 to 14.0, copies of read-only repositories.
- In GitLab 14.1 and later, unavailable repositories.
- In GitLab 14.1 and later, [`-partially-unavailable`](#unavailable-replicas-of-available-repositories)
that specifies whether to include in the output repositories that are available but have
some assigned copies that are not available.
NOTE:
`dataloss` is still in beta and the output format is subject to change.
To check for repositories with outdated primaries or for unavailable repositories, run:
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml dataloss [-virtual-storage <virtual-storage>]
```
Every configured virtual storage is checked if none is specified:
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml dataloss
```
Repositories are listed in the output that have either:
- An outdated copy of the repository on the primary, in GitLab 13.0 to GitLab 14.0.
- No healthy and fully up-to-date copies available, in GitLab 14.1 and later.
The following information is printed for each repository:
- A repository's relative path to the storage directory identifies each repository and groups the related
information.
- The repository's current status is printed in parentheses next to the disk path:
- In GitLab 13.0 to 14.0, either `(read-only)` if the repository's primary node is outdated
and can't accept writes. Otherwise, `(writable)`.
- In GitLab 14.1 and later, `(unavailable)` is printed next to the disk path if the
repository is unavailable.
- The primary field lists the repository's current primary. If the repository has no primary, the field shows
`No Primary`.
- The In-Sync Storages lists replicas which have replicated the latest successful write and all writes
preceding it.
- The Outdated Storages lists replicas which contain an outdated copy of the repository. Replicas which have no copy
of the repository but should contain it are also listed here. The maximum number of changes the replica is missing
is listed next to replica. It's important to notice that the outdated replicas may be fully up to date or contain
later changes but Praefect can't guarantee it.
Additional information includes:
- Whether a node is assigned to host the repository is listed with each node's status.
`assigned host` is printed next to nodes that are assigned to store the repository. The
text is omitted if the node contains a copy of the repository but is not assigned to store
the repository. Such copies aren't kept in sync by Praefect, but may act as replication
sources to bring assigned copies up to date.
- In GitLab 14.1 and later, `unhealthy` is printed next to the copies that are located
on unhealthy Gitaly nodes.
Example output:
```shell
Virtual storage: default
Outdated repositories:
@hashed/3f/db/3fdba35f04dc8c462986c992bcf875546257113072a909c162f7e470e581e278.git (unavailable):
Primary: gitaly-1
In-Sync Storages:
gitaly-2, assigned host, unhealthy
Outdated Storages:
gitaly-1 is behind by 3 changes or less, assigned host
gitaly-3 is behind by 3 changes or less
```
A confirmation is printed out when every repository is available. For example:
```shell
Virtual storage: default
All repositories are available!
```
#### Unavailable replicas of available repositories
NOTE:
In GitLab 14.0 and earlier, the flag is `-partially-replicated` and the output shows any repositories with assigned nodes with outdated
copies.
To also list information of repositories which are available but are unavailable from some of the assigned nodes,
use the `-partially-unavailable` flag.
A repository is available if there is a healthy, up to date replica available. Some of the assigned secondary
replicas may be temporarily unavailable for access while they are waiting to replicate the latest changes.
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml dataloss [-virtual-storage <virtual-storage>] [-partially-unavailable]
```
Example output:
```shell
Virtual storage: default
Outdated repositories:
@hashed/3f/db/3fdba35f04dc8c462986c992bcf875546257113072a909c162f7e470e581e278.git:
Primary: gitaly-1
In-Sync Storages:
gitaly-1, assigned host
Outdated Storages:
gitaly-2 is behind by 3 changes or less, assigned host
gitaly-3 is behind by 3 changes or less
```
With the `-partially-unavailable` flag set, a confirmation is printed out if every assigned replica is fully up to
date and healthy.
For example:
```shell
Virtual storage: default
All repositories are fully available on all assigned storages!
```
### Check repository checksums
To check a project's repository checksums across on all Gitaly nodes, run the
[replicas Rake task](../raketasks/praefect.md#replica-checksums) on the main GitLab node.
### Accept data loss
WARNING:
`accept-dataloss` causes permanent data loss by overwriting other versions of the repository. Data
[recovery efforts](#data-recovery) must be performed before using it.
If it is not possible to bring one of the up to date replicas back online, you may have to accept data
loss. When accepting data loss, Praefect marks the chosen replica of the repository as the latest version
and replicates it to the other assigned Gitaly nodes. This process overwrites any other version of the
repository so care must be taken.
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml accept-dataloss
-virtual-storage <virtual-storage> -repository <relative-path> -authoritative-storage <storage-name>
```
### Enable writes or accept data loss
WARNING:
`accept-dataloss` causes permanent data loss by overwriting other versions of the repository.
Data [recovery efforts](#data-recovery) must be performed before using it.
Praefect provides the following subcommands to re-enable writes or accept data loss:
- In GitLab 13.2 and earlier, `enable-writes` to re-enable virtual storage for writes after
data recovery attempts:
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml enable-writes -virtual-storage <virtual-storage>
```
- In GitLab 13.3 and later, if it is not possible to bring one of the up to date nodes back
online, you may have to accept data loss:
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml accept-dataloss -virtual-storage <virtual-storage> -repository <relative-path> -authoritative-storage <storage-name>
```
When accepting data loss, Praefect:
1. Marks the chosen copy of the repository as the latest version.
1. Replicates the copy to the other assigned Gitaly nodes.
This process overwrites any other copy of the repository so care must be taken.
## Data recovery
If a Gitaly node fails replication jobs for any reason, it ends up hosting outdated versions of the
affected repositories. Praefect provides tools for:
- [Automatic](#automatic-reconciliation) reconciliation, for GitLab 13.4 and later.
- [Manual](#manual-reconciliation) reconciliation, for:
- GitLab 13.3 and earlier.
- Repositories upgraded to GitLab 13.4 and later without entries in the `repositories` table. In
GitLab 13.6 and later, [a migration is run](https://gitlab.com/gitlab-org/gitaly/-/issues/3033)
when Praefect starts for these repositories.
These tools reconcile the outdated repositories to bring them fully up to date again.
### Automatic reconciliation
> [Introduced](https://gitlab.com/gitlab-org/gitaly/-/issues/2717) in GitLab 13.4.
Praefect automatically reconciles repositories that are not up to date. By default, this is done every
five minutes. For each outdated repository on a healthy Gitaly node, the Praefect picks a
random, fully up-to-date replica of the repository on another healthy Gitaly node to replicate from. A
replication job is scheduled only if there are no other replication jobs pending for the target
repository.
The reconciliation frequency can be changed via the configuration. The value can be any valid
[Go duration value](https://golang.org/pkg/time/#ParseDuration). Values below 0 disable the feature.
Examples:
```ruby
praefect['reconciliation_scheduling_interval'] = '5m' # the default value
```
```ruby
praefect['reconciliation_scheduling_interval'] = '30s' # reconcile every 30 seconds
```
```ruby
praefect['reconciliation_scheduling_interval'] = '0' # disable the feature
```
### Manual reconciliation
WARNING:
The `reconcile` sub-command was removed in GitLab 14.1. Use [automatic reconciliation](#automatic-reconciliation) instead. Manual reconciliation may produce excess replication jobs and is limited in functionality. Manual reconciliation does not work when [repository-specific primary nodes](#repository-specific-primary-nodes) are
enabled.
The Praefect `reconcile` sub-command allows for the manual reconciliation between two Gitaly nodes. The
command replicates every repository on a later version on the reference storage to the target storage.
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml reconcile -virtual <virtual-storage> -reference <up-to-date-storage> -target <outdated-storage> -f
```
- Replace the placeholder `<virtual-storage>` with the virtual storage containing the Gitaly node storage to be checked.
- Replace the placeholder `<up-to-date-storage>` with the Gitaly storage name containing up to date repositories.
- Replace the placeholder `<outdated-storage>` with the Gitaly storage name containing outdated repositories.
### Manually remove repositories
> [Introduced](https://gitlab.com/gitlab-org/gitaly/-/merge_requests/3767) in GitLab 14.3.
The `remove-repository` Praefect sub-command removes repositories from a Gitaly Cluster. It removes
all state associated with a given repository including:
- On-disk repositories on all relevant Gitaly nodes.
- Any database state tracked by Praefect.
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml remove-repository -virtual-storage <virtual-storage> -repository <repository>
```
- `-virtual-storage` is the virtual storage the repository is located in. Virtual storages are configured in `/etc/gitlab/gitlab.rb` under `praefect['virtual_storages]` and looks like the following:
```ruby
praefect['virtual_storages'] = {
'default' => {
...
},
'storage-1' => {
...
}
}
```
In this example, the virtual storage to specify is `default` or `storage-1`.
- `-repository` is the repository's relative path in the storage [beginning with `@hashed`](../repository_storage_types.md#hashed-storage).
For example:
```plaintext
@hashed/f5/ca/f5ca38f748a1d6eaf726b8a42fb575c3c71f1864a8143301782de13da2d9202b.git
```
Parts of the repository can continue to exist after running `remove-repository`. This can be because of:
- A deletion error.
- An in-flight RPC call targeting the repository.
If this occurs, run `remove-repository` again.
### Manually list untracked repositories
> [Introduced](https://gitlab.com/gitlab-org/gitaly/-/merge_requests/3926) in GitLab 14.4.
The `list-untracked-repositories` Praefect sub-command lists repositories of the Gitaly Cluster that both:
- Exist for at least one Gitaly storage.
- Aren't tracked in the Praefect database.
The command outputs:
- Result to `STDOUT` and the command's logs.
- Errors to `STDERR`.
Each entry is a complete JSON string with a newline at the end (configurable using the
`-delimiter` flag). For example:
```plaintext
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml list-untracked-repositories
{"virtual_storage":"default","storage":"gitaly-1","relative_path":"@hashed/ab/cd/abcd123456789012345678901234567890123456789012345678901234567890.git"}
{"virtual_storage":"default","storage":"gitaly-1","relative_path":"@hashed/ab/cd/abcd123456789012345678901234567890123456789012345678901234567891.git"}
```
### Manually track repositories
> [Introduced](https://gitlab.com/gitlab-org/omnibus-gitlab/-/merge_requests/5658) in GitLab 14.4.
The `track-repository` Praefect sub-command adds repositories on disk to the Praefect database to be tracked.
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml track-repository -virtual-storage <virtual-storage> -repository <repository>
```
- `-virtual-storage` is the virtual storage the repository is located in. Virtual storages are configured in `/etc/gitlab/gitlab.rb` under `praefect['virtual_storages]` and looks like the following:
```ruby
praefect['virtual_storages'] = {
'default' => {
...
},
'storage-1' => {
...
}
}
```
In this example, the virtual storage to specify is `default` or `storage-1`.
- `-repository` is the repository's relative path in the storage [beginning with `@hashed`](../repository_storage_types.md#hashed-storage).
For example:
```plaintext
@hashed/f5/ca/f5ca38f748a1d6eaf726b8a42fb575c3c71f1864a8143301782de13da2d9202b.git
```
- `-authoritative-storage` is the storage we want Praefect to treat as the primary. Required if
[per-repository replication](#configure-replication-factor) is set as the replication strategy.
The command outputs:
- Results to `STDOUT` and the command's logs.
- Errors to `STDERR`.
This command fails if:
- The repository is already being tracked by the Praefect database.
- The repository does not exist on disk.
doc/administration/gitaly/recovery.md 0 → 100644
View file @ bb605763
---
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
---
# Recovery options
Gitaly Cluster can [recover from certain types of failure](recovery.md).
## Primary Node Failure
Gitaly Cluster recovers from a failing primary Gitaly node by promoting a healthy secondary as the
new primary.
In GitLab 14.1 and later, Gitaly Cluster:
- Elects a healthy secondary with a fully up to date copy of the repository as the new primary.
- Repository becomes unavailable if there are no fully up to date copies of it on healthy secondaries.
To minimize data loss in GitLab 13.0 to 14.0, Gitaly Cluster:
- Switches repositories that are outdated on the new primary to [read-only mode](#read-only-mode).
- Elects the secondary with the least unreplicated writes from the primary to be the new
primary. Because there can still be some unreplicated writes,
[data loss can occur](#check-for-data-loss).
### Read-only mode
> - Introduced in GitLab 13.0 as [generally available](https://about.gitlab.com/handbook/product/gitlab-the-product/#generally-available-ga).
> - Between GitLab 13.0 and GitLab 13.2, read-only mode applied to the whole virtual storage and occurred whenever failover occurred.
> - [In GitLab 13.3 and later](https://gitlab.com/gitlab-org/gitaly/-/issues/2862), read-only mode applies on a per-repository basis and only occurs if a new primary is out of date.
new primary. If the failed primary contained unreplicated writes, [data loss can occur](#check-for-data-loss).
> - Removed in GitLab 14.1. Instead, repositories [become unavailable](#unavailable-repositories).
When Gitaly Cluster switches to a new primary in GitLab 13.0 to 14.0, repositories enter
read-only mode if they are out of date. This can happen after failing over to an outdated
secondary. Read-only mode eases data recovery efforts by preventing writes that may conflict
with the unreplicated writes on other nodes.
To enable writes again in GitLab 13.0 to 14.0, an administrator can:
1. [Check](#check-for-data-loss) for data loss.
1. Attempt to [recover](#data-recovery) missing data.
1. Either [enable writes](#enable-writes-or-accept-data-loss) in the virtual storage or
[accept data loss](#enable-writes-or-accept-data-loss) if necessary, depending on the version of
GitLab.
## Unavailable repositories
> - From GitLab 13.0 through 14.0, repositories became read-only if they were outdated on the primary but fully up to date on a healthy secondary. `dataloss` sub-command displays read-only repositories by default through these versions.
> - Since GitLab 14.1, Praefect contains more responsive failover logic which immediately fails over to one of the fully up to date secondaries rather than placing the repository in read-only mode. Since GitLab 14.1, the `dataloss` sub-command displays repositories which are unavailable due to having no fully up to date copies on healthy Gitaly nodes.
A repository is unavailable if all of its up to date replicas are unavailable. Unavailable repositories are
not accessible through Praefect to prevent serving stale data that may break automated tooling.
### Check for data loss
The Praefect `dataloss` subcommand identifies:
- Copies of repositories in GitLab 13.0 to GitLab 14.0 that at are likely to be outdated.
This can help identify potential data loss after a failover.
- Repositories in GitLab 14.1 and later that are unavailable. This helps identify potential
data loss and repositories which are no longer accessible because all of their up-to-date
replicas copies are unavailable.
The following parameters are available:
- `-virtual-storage` that specifies which virtual storage to check. Because they might require
an administrator to intervene, the default behavior is to display:
- In GitLab 13.0 to 14.0, copies of read-only repositories.
- In GitLab 14.1 and later, unavailable repositories.
- In GitLab 14.1 and later, [`-partially-unavailable`](#unavailable-replicas-of-available-repositories)
that specifies whether to include in the output repositories that are available but have
some assigned copies that are not available.
NOTE:
`dataloss` is still in beta and the output format is subject to change.
To check for repositories with outdated primaries or for unavailable repositories, run:
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml dataloss [-virtual-storage <virtual-storage>]
```
Every configured virtual storage is checked if none is specified:
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml dataloss
```
Repositories are listed in the output that have either:
- An outdated copy of the repository on the primary, in GitLab 13.0 to GitLab 14.0.
- No healthy and fully up-to-date copies available, in GitLab 14.1 and later.
The following information is printed for each repository:
- A repository's relative path to the storage directory identifies each repository and groups the related
information.
- The repository's current status is printed in parentheses next to the disk path:
- In GitLab 13.0 to 14.0, either `(read-only)` if the repository's primary node is outdated
and can't accept writes. Otherwise, `(writable)`.
- In GitLab 14.1 and later, `(unavailable)` is printed next to the disk path if the
repository is unavailable.
- The primary field lists the repository's current primary. If the repository has no primary, the field shows
`No Primary`.
- The In-Sync Storages lists replicas which have replicated the latest successful write and all writes
preceding it.
- The Outdated Storages lists replicas which contain an outdated copy of the repository. Replicas which have no copy
of the repository but should contain it are also listed here. The maximum number of changes the replica is missing
is listed next to replica. It's important to notice that the outdated replicas may be fully up to date or contain
later changes but Praefect can't guarantee it.
Additional information includes:
- Whether a node is assigned to host the repository is listed with each node's status.
`assigned host` is printed next to nodes that are assigned to store the repository. The
text is omitted if the node contains a copy of the repository but is not assigned to store
the repository. Such copies aren't kept in sync by Praefect, but may act as replication
sources to bring assigned copies up to date.
- In GitLab 14.1 and later, `unhealthy` is printed next to the copies that are located
on unhealthy Gitaly nodes.
Example output:
```shell
Virtual storage: default
Outdated repositories:
@hashed/3f/db/3fdba35f04dc8c462986c992bcf875546257113072a909c162f7e470e581e278.git (unavailable):
Primary: gitaly-1
In-Sync Storages:
gitaly-2, assigned host, unhealthy
Outdated Storages:
gitaly-1 is behind by 3 changes or less, assigned host
gitaly-3 is behind by 3 changes or less
```
A confirmation is printed out when every repository is available. For example:
```shell
Virtual storage: default
All repositories are available!
```
#### Unavailable replicas of available repositories
NOTE:
In GitLab 14.0 and earlier, the flag is `-partially-replicated` and the output shows any repositories with assigned nodes with outdated
copies.
To also list information of repositories which are available but are unavailable from some of the assigned nodes,
use the `-partially-unavailable` flag.
A repository is available if there is a healthy, up to date replica available. Some of the assigned secondary
replicas may be temporarily unavailable for access while they are waiting to replicate the latest changes.
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml dataloss [-virtual-storage <virtual-storage>] [-partially-unavailable]
```
Example output:
```shell
Virtual storage: default
Outdated repositories:
@hashed/3f/db/3fdba35f04dc8c462986c992bcf875546257113072a909c162f7e470e581e278.git:
Primary: gitaly-1
In-Sync Storages:
gitaly-1, assigned host
Outdated Storages:
gitaly-2 is behind by 3 changes or less, assigned host
gitaly-3 is behind by 3 changes or less
```
With the `-partially-unavailable` flag set, a confirmation is printed out if every assigned replica is fully up to
date and healthy.
For example:
```shell
Virtual storage: default
All repositories are fully available on all assigned storages!
```
### Check repository checksums
To check a project's repository checksums across on all Gitaly nodes, run the
[replicas Rake task](../raketasks/praefect.md#replica-checksums) on the main GitLab node.
### Accept data loss
WARNING:
`accept-dataloss` causes permanent data loss by overwriting other versions of the repository. Data
[recovery efforts](#data-recovery) must be performed before using it.
If it is not possible to bring one of the up to date replicas back online, you may have to accept data
loss. When accepting data loss, Praefect marks the chosen replica of the repository as the latest version
and replicates it to the other assigned Gitaly nodes. This process overwrites any other version of the
repository so care must be taken.
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml accept-dataloss
-virtual-storage <virtual-storage> -repository <relative-path> -authoritative-storage <storage-name>
```
### Enable writes or accept data loss
WARNING:
`accept-dataloss` causes permanent data loss by overwriting other versions of the repository.
Data [recovery efforts](#data-recovery) must be performed before using it.
Praefect provides the following subcommands to re-enable writes or accept data loss:
- In GitLab 13.2 and earlier, `enable-writes` to re-enable virtual storage for writes after
data recovery attempts:
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml enable-writes -virtual-storage <virtual-storage>
```
- In GitLab 13.3 and later, if it is not possible to bring one of the up to date nodes back
online, you may have to accept data loss:
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml accept-dataloss -virtual-storage <virtual-storage> -repository <relative-path> -authoritative-storage <storage-name>
```
When accepting data loss, Praefect:
1. Marks the chosen copy of the repository as the latest version.
1. Replicates the copy to the other assigned Gitaly nodes.
This process overwrites any other copy of the repository so care must be taken.
## Data recovery
If a Gitaly node fails replication jobs for any reason, it ends up hosting outdated versions of the
affected repositories. Praefect provides tools for:
- [Automatic](#automatic-reconciliation) reconciliation, for GitLab 13.4 and later.
- [Manual](#manual-reconciliation) reconciliation, for:
- GitLab 13.3 and earlier.
- Repositories upgraded to GitLab 13.4 and later without entries in the `repositories` table. In
GitLab 13.6 and later, [a migration is run](https://gitlab.com/gitlab-org/gitaly/-/issues/3033)
when Praefect starts for these repositories.
These tools reconcile the outdated repositories to bring them fully up to date again.
### Automatic reconciliation
> [Introduced](https://gitlab.com/gitlab-org/gitaly/-/issues/2717) in GitLab 13.4.
Praefect automatically reconciles repositories that are not up to date. By default, this is done every
five minutes. For each outdated repository on a healthy Gitaly node, the Praefect picks a
random, fully up-to-date replica of the repository on another healthy Gitaly node to replicate from. A
replication job is scheduled only if there are no other replication jobs pending for the target
repository.
The reconciliation frequency can be changed via the configuration. The value can be any valid
[Go duration value](https://golang.org/pkg/time/#ParseDuration). Values below 0 disable the feature.
Examples:
```ruby
praefect['reconciliation_scheduling_interval'] = '5m' # the default value
```
```ruby
praefect['reconciliation_scheduling_interval'] = '30s' # reconcile every 30 seconds
```
```ruby
praefect['reconciliation_scheduling_interval'] = '0' # disable the feature
```
### Manual reconciliation
WARNING:
The `reconcile` sub-command was removed in GitLab 14.1. Use [automatic reconciliation](#automatic-reconciliation) instead.
Manual reconciliation may produce excess replication jobs and is limited in functionality. Manual reconciliation does not
work when [repository-specific primary nodes](praefect.md#repository-specific-primary-nodes) are enabled.
The Praefect `reconcile` sub-command allows for the manual reconciliation between two Gitaly nodes. The
command replicates every repository on a later version on the reference storage to the target storage.
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml reconcile -virtual <virtual-storage> -reference <up-to-date-storage> -target <outdated-storage> -f
```
- Replace the placeholder `<virtual-storage>` with the virtual storage containing the Gitaly node storage to be checked.
- Replace the placeholder `<up-to-date-storage>` with the Gitaly storage name containing up to date repositories.
- Replace the placeholder `<outdated-storage>` with the Gitaly storage name containing outdated repositories.
### Manually remove repositories
> [Introduced](https://gitlab.com/gitlab-org/gitaly/-/merge_requests/3767) in GitLab 14.3.
The `remove-repository` Praefect sub-command removes repositories from a Gitaly Cluster. It removes
all state associated with a given repository including:
- On-disk repositories on all relevant Gitaly nodes.
- Any database state tracked by Praefect.
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml remove-repository -virtual-storage <virtual-storage> -repository <repository>
```
- `-virtual-storage` is the virtual storage the repository is located in. Virtual storages are configured in `/etc/gitlab/gitlab.rb` under `praefect['virtual_storages]` and looks like the following:
```ruby
praefect['virtual_storages'] = {
'default' => {
...
},
'storage-1' => {
...
}
}
```
In this example, the virtual storage to specify is `default` or `storage-1`.
- `-repository` is the repository's relative path in the storage [beginning with `@hashed`](../repository_storage_types.md#hashed-storage).
For example:
```plaintext
@hashed/f5/ca/f5ca38f748a1d6eaf726b8a42fb575c3c71f1864a8143301782de13da2d9202b.git
```
Parts of the repository can continue to exist after running `remove-repository`. This can be because of:
- A deletion error.
- An in-flight RPC call targeting the repository.
If this occurs, run `remove-repository` again.
### Manually list untracked repositories
> [Introduced](https://gitlab.com/gitlab-org/gitaly/-/merge_requests/3926) in GitLab 14.4.
The `list-untracked-repositories` Praefect sub-command lists repositories of the Gitaly Cluster that both:
- Exist for at least one Gitaly storage.
- Aren't tracked in the Praefect database.
The command outputs:
- Result to `STDOUT` and the command's logs.
- Errors to `STDERR`.
Each entry is a complete JSON string with a newline at the end (configurable using the
`-delimiter` flag). For example:
```plaintext
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml list-untracked-repositories
{"virtual_storage":"default","storage":"gitaly-1","relative_path":"@hashed/ab/cd/abcd123456789012345678901234567890123456789012345678901234567890.git"}
{"virtual_storage":"default","storage":"gitaly-1","relative_path":"@hashed/ab/cd/abcd123456789012345678901234567890123456789012345678901234567891.git"}
```
### Manually track repositories
> [Introduced](https://gitlab.com/gitlab-org/omnibus-gitlab/-/merge_requests/5658) in GitLab 14.4.
The `track-repository` Praefect sub-command adds repositories on disk to the Praefect database to be tracked.
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml track-repository -virtual-storage <virtual-storage> -repository <repository>
```
- `-virtual-storage` is the virtual storage the repository is located in. Virtual storages are configured in `/etc/gitlab/gitlab.rb` under `praefect['virtual_storages]` and looks like the following:
```ruby
praefect['virtual_storages'] = {
'default' => {
...
},
'storage-1' => {
...
}
}
```
In this example, the virtual storage to specify is `default` or `storage-1`.
- `-repository` is the repository's relative path in the storage [beginning with `@hashed`](../repository_storage_types.md#hashed-storage).
For example:
```plaintext
@hashed/f5/ca/f5ca38f748a1d6eaf726b8a42fb575c3c71f1864a8143301782de13da2d9202b.git
```
- `-authoritative-storage` is the storage we want Praefect to treat as the primary. Required if
[per-repository replication](praefect.md#configure-replication-factor) is set as the replication strategy.
The command outputs:
- Results to `STDOUT` and the command's logs.
- Errors to `STDERR`.
This command fails if:
- The repository is already being tracked by the Praefect database.
- The repository does not exist on disk.
doc/administration/gitaly/troubleshooting.md
View file @ bb605763
...@@ -376,7 +376,7 @@ Here are common errors and potential causes: ...@@ -376,7 +376,7 @@ Here are common errors and potential causes:
To determine the primary node of a repository: To determine the primary node of a repository:
- In GitLab 14.6 and later, use the [`praefect metadata`](praefect.md#retrieve-repository-metadata) subcommand. - In GitLab 14.6 and later, use the [`praefect metadata`](#view-repository-metadata) subcommand.
- In GitLab 13.12 to GitLab 14.5 with [repository-specific primaries](praefect.md#repository-specific-primary-nodes), - In GitLab 13.12 to GitLab 14.5 with [repository-specific primaries](praefect.md#repository-specific-primary-nodes),
use the [`gitlab:praefect:replicas` Rake task](../raketasks/praefect.md#replica-checksums). use the [`gitlab:praefect:replicas` Rake task](../raketasks/praefect.md#replica-checksums).
- With legacy election strategies in GitLab 13.12 and earlier, the primary was the same for all repositories in a virtual storage. - With legacy election strategies in GitLab 13.12 and earlier, the primary was the same for all repositories in a virtual storage.
...@@ -392,13 +392,97 @@ To determine the primary node of a repository: ...@@ -392,13 +392,97 @@ To determine the primary node of a repository:
curl localhost:9652/metrics | grep gitaly_praefect_primaries` curl localhost:9652/metrics | grep gitaly_praefect_primaries`
``` ```
### View repository metadata
> [Introduced](https://gitlab.com/gitlab-org/gitaly/-/issues/3481) in GitLab 14.6.
Gitaly Cluster maintains a [metadata database](index.md#components) about the repositories stored on the cluster. Use the `praefect metadata` subcommand
to inspect the metadata for troubleshooting.
You can retrieve a repository's metadata by its Praefect-assigned repository ID:
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml metadata -repository-id <repository-id>
```
You can also retrieve a repository's metadata by its virtual storage and relative path:
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml metadata -virtual-storage <virtual-storage> -relative-path <relative-path>
```
#### Examples
To retrieve the metadata for a repository with a Praefect-assigned repository ID of 1:
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml metadata -repository-id 1
```
To retrieve the metadata for a repository with virtual storage `default` and relative path `@hashed/b1/7e/b17ef6d19c7a5b1ee83b907c595526dcb1eb06db8227d650d5dda0a9f4ce8cd9.git`:
```shell
sudo /opt/gitlab/embedded/bin/praefect -config /var/opt/gitlab/praefect/config.toml metadata -virtual-storage default -relative-path @hashed/b1/7e/b17ef6d19c7a5b1ee83b907c595526dcb1eb06db8227d650d5dda0a9f4ce8cd9.git
```
Either of these examples retrieve the following metadata for an example repository:
```plaintext
Repository ID: 54771
Virtual Storage: "default"
Relative Path: "@hashed/b1/7e/b17ef6d19c7a5b1ee83b907c595526dcb1eb06db8227d650d5dda0a9f4ce8cd9.git"
Replica Path: "@hashed/b1/7e/b17ef6d19c7a5b1ee83b907c595526dcb1eb06db8227d650d5dda0a9f4ce8cd9.git"
Primary: "gitaly-1"
Generation: 1
Replicas:
- Storage: "gitaly-1"
Assigned: true
Generation: 1, fully up to date
Healthy: true
Valid Primary: true
- Storage: "gitaly-2"
Assigned: true
Generation: 0, behind by 1 changes
Healthy: true
Valid Primary: false
- Storage: "gitaly-3"
Assigned: true
Generation: replica not yet created
Healthy: false
Valid Primary: false
```
#### Available metadata
The metadata retrieved by `praefect metadata` includes the fields in the following tables.
| Field | Description |
|:------------------|:-------------------------------------------------------------------------------------------------------------------|
| `Repository ID` | Permanent unique ID assigned to the repository by Praefect. Different to the ID GitLab uses for repositories. |
| `Virtual Storage` | Name of the virtual storage the repository is stored in. |
| `Relative Path` | Repository's path in the virtual storage. |
| `Replica Path` | Where on the Gitaly node's disk the repository's replicas are stored. |
| `Primary` | Current primary of the repository. |
| `Generation` | Used by Praefect to track repository changes. Each write in the repository increments the repository's generation. |
| `Replicas` | A list of replicas that exist or are expected to exist. |
For each replica, the following metadata is available:
| `Replicas` Field | Description |
|:-----------------|:-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `Storage` | Name of the Gitaly storage that contains the replica. |
| `Assigned` | Indicates whether the replica is expected to exist in the storage. Can be `false` if a Gitaly node is removed from the cluster or if the storage contains an extra copy after the repository's replication factor was decreased. |
| `Generation` | Latest confirmed generation of the replica. It indicates:<br><br>- The replica is fully up to date if the generation matches the repository's generation.<br>- The replica is outdated if the replica's generation is less than the repository's generation.<br>- `replica not yet created` if the replica does not yet exist at all on the storage. |
| `Healthy` | Indicates whether the Gitaly node that is hosting this replica is considered healthy by the consensus of Praefect nodes. |
| `Valid Primary` | Indicates whether the replica is fit to serve as the primary node. If the repository's primary is not a valid primary, a failover occurs on the next write to the repository if there is another replica that is a valid primary. A replica is a valid primary if:<br><br>- It is stored on a healthy Gitaly node.<br>- It is fully up to date.<br>- It is not targeted by a pending deletion job from decreasing replication factor.<br>- It is assigned. |
### Check that repositories are in sync ### Check that repositories are in sync
Is [some cases](index.md#known-issues) the Praefect database can get out of sync with the underlying Gitaly nodes. To check that Is [some cases](index.md#known-issues) the Praefect database can get out of sync with the underlying Gitaly nodes. To check that
a given repository is fully synced on all nodes, run the [`gitlab:praefect:replicas` Rake task](../raketasks/praefect.md#replica-checksums) a given repository is fully synced on all nodes, run the [`gitlab:praefect:replicas` Rake task](../raketasks/praefect.md#replica-checksums)
that checksums the repository on all Gitaly nodes. that checksums the repository on all Gitaly nodes.
The [Praefect dataloss](praefect.md#check-for-data-loss) command only checks the state of the repo in the Praefect database, and cannot The [Praefect dataloss](recovery.md#check-for-data-loss) command only checks the state of the repo in the Praefect database, and cannot
be relied to detect sync problems in this scenario. be relied to detect sync problems in this scenario.
### Relation does not exist errors ### Relation does not exist errors
......
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