Multi-region Namespace - Temporal Cloud feature guide

Support, stability, and dependency info

Multi-region Namespaces are in Public Preview for Temporal Cloud.

Temporal Cloud's multi-region Namespaces offer disaster-tolerant deployment for workloads with high availability requirements. With the multi-region feature enabled, Temporal Cloud automates failover and synchronizes data between Namespaces in different regions. You benefit from easy deployment and operational continuity to ensure data integrity, even in the face of unexpected challenges such as regional disruptions.

For each multi-region Namespace, you designate a standby region in addition to your primary active region. The Temporal Cloud Service replicates data from the active region to the standby region. This means your standby region is always available and synchronized with the active region. In the event of network service and performance issues in the active region, your standby region is ready to take over. When necessary, Temporal Cloud smoothly transitions control from the active to the standby region using a process called "failover".

Temporal Cloud's multi-region Namespace feature includes a 99.99% contractual Service Level Agreement (SLA). It provides 99.99% availability and 99.99% guarantee against service errors.

This feature guide covers the following topics:

• Choosing multi-region
• Failovers
• Multi-region Namespace SLA
• Architecture
• Pricing
• Manage your multi-region Namespace
• Operations

Choosing multi-region

Why choose a multi-region Namespace?

A high-availability multi-region Namespace (MRN) creates a single logical Namespace that operates across two physical regions: one active and one standby. MRNs streamline access for both regions to a unified Namespace endpoint. As Workflows progress in the active region, history events asynchronously replicate to the standby region, ensuring continuity and data integrity.

In the event of an incident or outage in the active region, Temporal Cloud will seamlessly failover to your standby region. After failover, the roles of the active and standby regions switch. Failovers enable already existing Workflow Executions to keep running and new Workflow Executions to be started.

In traditional active/active replication, multiple nodes serve requests and accept writes simultaneously with strong synchronous data consistency. With a Temporal Cloud multi-region Namespace, two replicated Namespaces (one active, one standby) accept requests, but not simultaneously. Requests are processed and Workflow history events are initially written to the active region, then asynchronously replicated to the standby region.

Before failover	After failover

Should you be using multi-region Namespaces? It depends on your availability requirements:

• Multi-region Namespaces offer a 99.99% contractual SLA for workloads with strict high-availability requirements. Multi-region Namespaces (MRNs) use two Namespaces in two deployment regions, to support standby recovery. In the event of a regional failure, Temporal Cloud automatically fails over the MRN Namespace to the standby region.
• Single-region Namespaces include a 99.9% contractual Service Level Agreement (SLA). In single-region use, Temporal clients connect to a single Namespace in one deployment region. For many applications, this offers sufficient availability.

Temporal Cloud provides 99.99% service availability for all Namespaces, both single-region and multi-region.

Upgrading to multi-region:

Enable the multi-region Namespace feature for your existing single-region Namespace by adding a second region to your Namespace. After adding the second region, Temporal Cloud begins data replication for your new standby region. Temporal Cloud notifies you by email once the replication has caught up and both regions are in sync.

Advantages of using a multi-region Namespace:

• No manual deployment or configuration needed, just simple push-button operation.
• Open Workflows continue in the standby region with minimal interruption and data loss.
• No changes needed for Worker and Workflow code during setup or failover.
• 99.99% Contractual SLA.

Failovers

What happens during the failover process?

Temporal Cloud will initiate a Namespace failover when it detects an incident or outage that elevates error rates or latency in the active region of a multi-region Namespace. A failover operation shifts Workflow processing to a standby region, unaffected by the incident. This ensures that existing Workflows can progress and new Workflows can be created as the incident is addressed. After Temporal-initiated failovers, Temporal Cloud shifts Workflow Execution processing back to the original region that was active before the incident (a "failback") once the incident is resolved.

info

You can test your multi-region Namespace by manually triggering failovers using the UI page or the 'tcld' CLI utility. In most scenarios, we recommend you let Temporal handle failovers for you.

Replication lag

Multi-region Namespaces use asynchronous replication between regions. Workflow updates in the active region, along with associated history events, are transmitted to the standby region with a short delay. This delay is called the replication lag. Temporal Cloud strives to maintain a P95 replication delay of less than 1 minute. In this context, P95 means 95% of requests are processed faster than this specified limit.

Replication lags mean a forced failover may cause Workflows to rollback in progress. Lags may also cause recently started Workflows to be temporarily unavailable until the active region recovers. Temporal event versioning and conflict resolution mechanisms help guarantee that the Workflow Event History can be replayed. Critical operations like Signals won't get lost.

Failover scenarios

The Temporal Cloud failover mechanism supports several modes to execute Namespace failovers. These modes include graceful failover ("handover"), forced failover, and a hybrid mode. The hybrid mode is Temporal Cloud’s default Namespace behavior.

Graceful failover (handover)

In this mode, replication tasks are fully processed and drained. Temporal Cloud pauses traffic to the Namespace before the failover. This prevents the loss of progress and avoids data conflicts. The Namespace experiences a short period of unavailability, defaulting to 10 seconds.

During this period, existing Workflows stop progress. Temporal Cloud returns a "Service unavailable error", which is retried by SDKs. State transitions will not happen and tasks are not dispatched. User requests like start/signal workflow will be rejected while operations are paused during handover.

This mode favors consistency over availability.

Forced failover

In this mode, a Namespace immediately activates in the standby region. Events not replicated due to replication lag will undergo conflict resolution upon reaching the new active region.

This mode prioritizes availability over consistency.

Hybrid failover mode

While graceful failovers are preferred for consistency, they aren’t always practical. Temporal Cloud’s hybrid failover mode (the default mode) limits an initial graceful failover attempt to 10 seconds or less. During this period, existing Workflows stop progress. Temporal Cloud returns a "Service unavailable error", which is retried by SDKs. If the graceful approach doesn’t resolve the issue, Temporal Cloud automatically switches to a forced failover. This strategy balances consistency and availability requirements.

See the sections on triggering a failover, Worker deployment, and routing for more information.

Multi-region Namespace SLA

What guarantees does Temporal offer for multi-region Namespaces?

Multi-region Namespaces offer 99.99% availability, enforced by Temporal Cloud's service error rates SLA. Our system is designed to limit data loss after recovery when the incident triggering the failover is resolved.

Our recovery point objective (RPO) is near-zero. There may be a short period of time during an incident or forced failover when some data is unavailable in the standby region. Some Workflow History data won't arrive until networks issue are fixed, enabling the History to finish replicating and the divergent History branches to reconcile.

Temporal Cloud proactively responds to incidents by triggering failovers. Our recovery time objective (RTO) is 20 minutes or less per incident.

info

During a disaster scenario in which the data on the hard drives in the active region cannot be recovered, the duration of data loss may be as high as the replication lag at the time of disaster.

Regional availability

Multi-region Namespaces are available in all existing Temporal Cloud regions.

tip

Namespace pairing is currently limited to regions within the same continent. South America is excluded as only one region is available.

Architecture

How do multi-region Namespaces work?

Multi-region Namespaces replicate Namespace metadata and Workflow Executions across connected regions. This redundancy, plus the added failover capability, provides measurable stability when dealing with outages.

A multi-region Namespace is normally active in a single region at any moment. The passive region assumes a standby role. An exception to this only occurs in the event of a network partition. In this case, you may elect to promote a standby region to active status. Caution: this action will temporarily result in both regions being active. Once the network partition resolves and communication between the regions is restored, a conflict resolution algorithm determines which region continues as the active one. This ensures only one region remains active.

Metadata replication

Updates to multi-region Namespace records automatically replicate across regions. This metadata includes configurations such as retention periods, Search Attributes, and other settings. Temporal Cloud ensures that all regions will eventually share a consistent and unified view of the Namespace metadata.

info

A Namespace failover, which changes the "active region" field of a Namespace record, is an update. This update is replicated via the Namespace metadata mechanism.

Workflow Execution replication

Temporal Cloud restricts certain Workflow operations to the active region:

• You may only update Workflows in the active region.
• You may only dispatch Workflow Tasks and Activity Tasks from the active region. Forward progress in a Workflow Execution can therefore only be made in the active region.

These limits mean that certain requests, such as Start Workflow and Signal Workflow, are processed by and limited to the active region. Standby regions may receive API requests from Clients and Workers. They automatically forward these requests to the active Namespace for execution.

Multi-region Namespaces provide an “all-active” experience for Temporal users. This helps limit or eliminate downtime during Namespace failover. There's a short time window from when a standby region becomes the active region to when Clients and Workers receive a DNS update. During this time requests forward from the now passive (formerly active) region to the newly active (formerly standby) region.

As Workflow Executions progress and are operated on, replication tasks created in the active region are dispatched to the standby region. Processing these replication tasks ensures that the standby region undergoes the same state transitions as the active region. This enables replicated tasks to synchronize and achieve the same state as the original tasks.

Standby regions do not distribute Workflow or Activity Tasks. Instead, they perform verification tasks to confirm that intended operations are executed so Workflows reach the desired state. This mechanism ensures consistency and reliability in the replication process across Temporal regions.

Conflict Resolution

Multi-region Namespaces rely on asynchronous event replication across Temporal regions. In the event of a non-graceful failover, replication lag may result in a temporary setback in workflow progress.

Single-region Namespaces can be configured to provide at-most-once semantics for Activities execution (when Maximum Attempts is set to 0). Multi-region Namespaces provide at-least-once semantics for execution of Activities. Completed Activities may be re-dispatched in a newly active region, leading to repeated executions.

When a Workflow Execution is updated in a new region following a failover, events from the previously active region that arrive after the failover can't be directly applied. At this point, Temporal Cloud has forked the Workflow History.

After failover, Temporal Cloud creates a new branch history for execution, and begins its conflict resolution process. The Temporal Service ensures that Workflow Histories remain valid and are replayable by SDKs post-failover or after conflict resolution. This capability is crucial for Workflow Executions to continue their forward progress.

danger

Design your activities to succeed once and only once. This "idempotent" approach avoids process duplication that could withdraw money twice or ship extra orders by mistake. Run-once actions maintain data integrity and prevent costly errors. Idempotency keeps operations from producing additional effects. Protect your processes from accidental or repeated actions for more reliable execution.

Pricing

How does adding a multi-region Namespace affect my costs?

For pricing details, visit Temporal Cloud's Pricing page.

Manage your multi-region Namespace

How do you create, enable, and manage your multi-region Namespace?

Temporal enables you to create and manage your multi-region Namespace using the Temporal Cloud Web UI, the command line 'tcld' CLI utility, and the Cloud Ops API. Use these tools to create, upgrade, and discontinue your multi-region Namespace.

• Create a multi-region Namespace
• Upgrade a single-region Namespace to multi-region
• Discontinuing multi-region service

danger

Only Global Admins and Namespace Admins may create an multi-region Namespace (MRN), upgrade an existing Namespace to MRN, or trigger an MRN failover.

Support, stability, and dependency info

Temporal Cloud’s Terraform provider does not support multi-region Namespaces.

Create a multi-region Namespace

The following sections explain how to create a new multi-region Namespace (MRN). MRNs provide multi-region deployment backed by Temporal's data replication and active-standby features.

tip

While reading through this coverage, remember that pairing is currently limited to regions within the same continent.

Temporal Cloud Web UI

During Namespace creation, specify the first region for the Namespace. Then, select the “Add a region” option. Adding a second region enables multi-region Namespace capabilities.

Temporal 'tcld' CLI

Start with the following command to create the new multi-region Namespace:

tcld namespace create --namespace <namespace_id> region <region> --region <region>

Include both regions by specifying the region codes as arguments to the --region flags. Before pressing return, add your authentication credentials. For example, --ca-certificate-file <path-to-pem-file>.

Upgrade an existing single-region Namespace to multi-region functionality

You can upgrade existing single-region Namespaces to a multi-region by adding a standby region. The following sections show you how.

Temporal Cloud Web UI

To upgrade an existing Namespace to a multi-region Namespace:

1. Visit Temporal Cloud Namespaces in your Web browser
2. Navigate to the Namespace details page
3. Select the “Add a region” button.
4. Select the standby region you want to add to this Namespace

You will see an estimated time for replication. This time is based on your selection and the size and scale of Workflows in your Namespace, An email alert is sent once your multi-region Namespace is ready for use.

Temporal 'tcld' CLI

At the command line, enter:

tcld namespace add-region --namespace <namespace_id> --region <region>

Specify the region code for the new region to add. Before pressing return, add your authentication credentials. For example, --ca-certificate-file <path-to-pem-file>. An email alert is sent once your multi-region Namespace is ready for use.

Discontinuing multi-region availability

Disabling multi-region removes the high availability and automatic failover features that provide Temporal's highest service level agreement. To disable the feature and end charges, users must contact Temporal Support directly. MRN-specific charges for replication will stop once this decommissioning procedure completes.

• When making your request you must let us know which region you want the Namespace to land in after removing the standby region.
• If you cease services in the middle of the month, your Namespace will be converted to a single region Namespace within 1 business day.
• Temporal won't retain replicated data in the standby region once multi-region has been disabled.
• After disabling multi-region, Temporal Cloud cannot re-enable the feature for a given Namespace for seven days.

Operations

How do you trigger failovers and observe Workflow Executions?

This section provides how-to instructions for the following operations tasks:

• Triggering failovers
• Metrics
• Monitoring and observability

Triggering failovers

Users also can trigger a failover during the outage of a non-Temporal controlled regional downstream dependency, or for testing purposes.

Temporal is responsible for detecting and triggering a failover for a multi-region Namespace in the event of a regional outage or a disaster. Users also can trigger a failover during the outage of a non-Temporal controlled regional downstream dependency, or for testing purposes.

The following sections show you how to perform this action, moving your active Namespace to the standby region. You'll also read about what to expect after a failover.

Check Your Replication Lag

Always check the metric replication lag before initiating a failover. A forced failover when there is a large replication lag has a higher likelihood of rolling back Workflow progress.

Temporal Cloud Web UI

Visit the Namespace Web UI page. Navigate to the Namespace details page and select the menu option to “Trigger a failover”. After confirming the operation, the failover is initiated.

Temporal 'tcld' CLI

To manually trigger a failover, issue the following from your command line:

tcld namespace failover --namespace <namespace_id> --region <target_region>

After failover

After any failover, whether triggered by you or by Temporal, event information appears in both the Temporal Cloud Web UI (on the Namespace detail page) and in your audit logs. The audit log entry for Failover uses the "operation": FailoverNamespace" event. After failover, the Namespace is active in the new region.

You needn't monitor Temporal Cloud's failover response in real-time. Whenever there is a failover event, you'll receive an alert email.

After Temporal-initiated failovers, Temporal Cloud shifts Workflow Execution processing back to the original region that was active before the incident (a "failback") once the incident is resolved. More information is available in Monitoring and Observability.

Metrics

Replication lag refers to the transmission delay of Workflow updates and history events from the active region to the standby region. A forced failover when there is a large replication lag has a higher likelihood of rolling back Workflow progress, so always check the metric replication lag before initiating a failover. Temporal Cloud emits three replication lag-specific metrics. The following samples demonstrate how you can use these metrics to explore replication lag.

P99 replication lag histogram

histogram_quantile(0.99, sum(rate(temporal_cloud_v0_replication_lag_bucket[$__rate_interval])) by (temporal_namespace, le))

Average replication lag

sum(rate(temporal_cloud_v0_replication_lag_sum[$__rate_interval])) by (temporal_namespace)
/
sum(rate(temporal_cloud_v0_replication_lag_count[$__rate_interval])) by (temporal_namespace)

Monitoring and observability

You can view and alert on key cloud metrics using the Web UI, the 'tcld' CLI utility, and Temporal Cloud APIs. For example, during the process of adding a region to a Namespace, you can see the progress of Workflow replication. Errors--if any--will also surface in the Namespace Web UI.

info

You may notice that multi-region Namespace shows twice (2x) the Action count in temporal_cloud_v0_total_action_count. This doubling happens due to regional replication.

Auditing operational events

Temporal Cloud provides several ways to audit events:

• When Temporal triggers failovers, the audit log updates with details. Look specifically for "operation": "FailoverNamespace" in the logs.
• You can set alerts for Temporal-initiated failover events.
• After a failover, you can check that the Namespace is active in the new region using the Temporal Cloud Web UI.

Worker Deployment

Enabling the multi-region Namespace does not require specific Worker configuration. The process is invisible to the Workers. When a Namespace fails over to the standby region, the DNS redirection orchestrated by Temporal ensures that your existing Workers continue to poll the Namespace without interruption. More details are available in the Routing section below.

info

• When a Namespace fails over to a standby region, Workers will be communicating cross-region.

• In case of a complete regional outage, Workers in the original region may fail alongside the original Namespace. To keep Workflows moving during this level of outage, deploy a second set of Workers to your standby region.

Routing

When using multi-region for a Namespace, the Namespace's DNS record <ns>.<acct>.<tmprl_domain> targets a regional DNS record in the format <region>.region.<tmprl_domain>. In this format, <region> is the currently active region for your Namespace. Clients resolving the Namespace’s DNS record are directed to connect to the active region for that Namespace, thanks to the regional DNS record.

During failover, Temporal Cloud changes the target of the Namespace DNS record from one region to another. Namespace DNS records are configured with a 15 seconds TTL. Any DNS cache should re-resolve the record within this delay. As a rule of thumb, DNS reconciliation takes no longer than twice (2x) the TTL. Clients should converge to the newly targeted region within, at, most a 30-second delay.

PrivateLink routing

info

Some networking configuration is required for failover to be transparent to clients and workers when using PrivateLink. This section describes how to configure routing for multi-region Namespaces for PrivateLink customers only.

PrivateLink customers may need to change certain configurations for multi-region Namespace use. Routing configuration depends on networking setup and use of PrivateLink. You may need to:

• override a DNS zone; and
• ensure the network connectivity between the two regions.

When using PrivateLink, you connect to Temporal Cloud using IP addresses local to your network. The region.<tmprl_domain> zone is configured in the Temporal systems as an independent zone. This allows you to override it to make sure traffic is routed internally for the regions in use. You can check the Namespace's active region using the Namespace record CNAME, which is public.

To set up the DNS override, you override specific regions to target the relevant IP addresses (e.g. aws-us-west-1.region.tmprl.cloud to target 192.168.1.2). Using AWS, this can be done using a private hosted zone in Route53 for region.<tmprl_domain>. Link that private zone to the VPCs you use for Workers.

When your Workers connect to the Namespace, they first resolve the <ns>.<acct>.<tmprl_domain> record. This targets <active>.region.<tmprl_domain> using a CNAME. Your private zone overrides that second DNS resolution, leading traffic to reach the internal IP you're using.

Consider how you'll configure Workers to run in this scenario. You might set Workers to run in both regions at all times. Alternately, you could establish connectivity between the regions to redirect Workers once failover occurs.

The following table lists Temporal's available regions, PrivateLink endpoints, and DNS record overrides. The sa-east-1 region listed here is not yet available for use with multi-region Namespaces.

Region	PrivateLink Service Name	DNS Record Override
ap-northeast-1	com.amazonaws.vpce.ap-northeast-1.vpce-svc-08f34c33f9fb8a48a	aws-ap-northeast-1.region.tmprl.cloud
ap-northeast-2	com.amazonaws.vpce.ap-northeast-2.vpce-svc-08c4d5445a5aad308	aws-ap-northeast-2.region.tmprl.cloud
ap-south-1	com.amazonaws.vpce.ap-south-1.vpce-svc-0ad4f8ed56db15662	aws-ap-south-1.region.tmprl.cloud
ap-south-2	com.amazonaws.vpce.ap-south-2.vpce-svc-08bcf602b646c69c1	aws-ap-south-2.region.tmprl.cloud
ap-southeast-1	com.amazonaws.vpce.ap-southeast-1.vpce-svc-05c24096fa89b0ccd	aws-ap-southeast-1.region.tmprl.cloud
ap-southeast-2	com.amazonaws.vpce.ap-southeast-2.vpce-svc-0634f9628e3c15b08	aws-ap-southeast-2.region.tmprl.cloud
ca-central-1	com.amazonaws.vpce.ca-central-1.vpce-svc-080a781925d0b1d9d	aws-ca-central-1.region.tmprl.cloud
eu-central-1	com.amazonaws.vpce.eu-central-1.vpce-svc-073a419b36663a0f3	aws-eu-central-1.region.tmprl.cloud
eu-west-1	com.amazonaws.vpce.eu-west-1.vpce-svc-04388e89f3479b739	aws-eu-west-1.region.tmprl.cloud
eu-west-2	com.amazonaws.vpce.eu-west-2.vpce-svc-0ac7f9f07e7fb5695	aws-eu-west-2.region.tmprl.cloud
sa-east-1	com.amazonaws.vpce.sa-east-1.vpce-svc-0ca67a102f3ce525a	aws-sa-east-1.region.tmprl.cloud
us-east-1	com.amazonaws.vpce.us-east-1.vpce-svc-0822256b6575ea37f	aws-us-east-1.region.tmprl.cloud
us-east-2	com.amazonaws.vpce.us-east-2.vpce-svc-01b8dccfc6660d9d4	aws-us-east-2.region.tmprl.cloud
us-west-2	com.amazonaws.vpce.us-west-2.vpce-svc-0f44b3d7302816b94	aws-us-west-2.region.tmprl.cloud

Learn more about multi-region Namespaces

If you have more questions or feedback about this feature, reach out to the product team.