Backup and restore in Azure Database for PostgreSQL - Flexible Server
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Azure Database for PostgreSQL - Flexible Server
Backups form an essential part of any business continuity strategy. They help protect data from accidental corruption or deletion.
Azure Database for PostgreSQL flexible server automatically performs regular backups of your server. You can then do a point-in-time recovery (PITR) within a retention period that you specify. The overall time to restore and recovery typically depends on the size of data and the amount of recovery to be performed.
Backup overview
Azure Database for PostgreSQL flexible server takes snapshot backups of data files and stores them securely in zone-redundant storage or locally redundant storage, depending on the region. The server also backs up transaction logs when the write-ahead log (WAL) file is ready to be archived. You can use these backups to restore a server to any point in time within your configured backup retention period.
The default backup retention period is 7 days, but you can extend the period to a maximum of 35 days. All backups are encrypted through AES 256-bit encryption for data stored at rest.
These backup files can't be exported or used to create servers outside Azure Database for PostgreSQL flexible server. For that purpose, you can use the PostgreSQL tools pg_dump and pg_restore/psql.
Backup frequency
Backups on Azure Database for PostgreSQL flexible server instances are snapshot based. The first snapshot backup is scheduled immediately after a server is created. Snapshot backups are currently taken once daily. If no further modifications are made to any databases on the server after the last snapshot backup, snapshot backups are temporarily suspended. As soon as any database on the server is modified, a new snapshot is immediately taken to capture the latest changes. The first snapshot is a full backup and consecutive snapshots are differential backups.
Transaction log backups happen at varied frequencies, depending on the workload and when the WAL file is filled and ready to be archived. In general, the delay RPO (recovery point objective) can be up to 5 minutes.
Backup redundancy options
Azure Database for PostgreSQL flexible server stores multiple copies of your backups to help protect your data from planned and unplanned events. These events can include transient hardware failures, network or power outages, and natural disasters. Backup redundancy helps ensure that your database meets its availability and durability targets, even if failures happen.
Azure Database for PostgreSQL flexible server offers three options:
Zone-redundant backup storage: This option is automatically chosen for regions that support availability zones. When backups are stored in zone-redundant backup storage, three copies of the data are kept within the availability zone where your server is hosted. Additionally, the data is replicated to another availability zone for added protection.
This option provides backup data availability across availability zones and restricts replication of data to within a country/region to meet data residency requirements. This option provides at least 99.9999999999 percent (12 nines) durability of backup objects over a year.
Locally redundant backup storage: This option is automatically chosen for regions that don't support availability zones yet. When the backups are stored in locally redundant backup storage, multiple copies of backups are stored in the same datacenter.
This option helps protect your data against server rack and drive failures. It provides at least 99.999999999 percent (11 nines) durability of backup objects over a year.
By default, backup storage for servers with same-zone high availability (HA) or no high-availability configuration is set to locally redundant.
Geo-redundant backup storage: You can choose this option at the time of server creation. When the backups are stored in geo-redundant backup storage, in addition to three copies of data stored within the region where your server is hosted, the data is replicated to a geo-paired region.
This option allows you to restore your server in a different region in the event of a disaster. It also provides at least 99.99999999999999 percent (16 nines) durability of backup objects over a year.
Geo-redundancy is supported for servers hosted in any of the Azure paired regions.
Moving from other backup storage options to geo-redundant backup storage
You can configure geo-redundant storage for backup only during server creation. After a server is provisioned, you can't change the backup storage redundancy option.
Backup retention
Backups are retained based on the retention period that you set for the server. You can select a retention period between 7 (default) and 35 days. You can set the retention period during server creation or change it at a later time. Backups are retained even for stopped servers.
The backup retention period governs the timeframe from which a PITR can be retrieved using the available backups. You can also treat the backup retention period as a recovery window from a restore perspective.
All backups required to perform a PITR within the backup retention period are retained in the backup storage. For example, if the backup retention period is set to 7 days, the recovery window is the last 7 days. In this scenario, all the data and logs that are required to restore and recover the server in the last 7 days are retained.
Backup storage cost
Azure Database for PostgreSQL flexible server provides up to 100 percent of your provisioned server storage as backup storage at no extra cost. Any extra backup storage that you use is charged in gigabytes per month.
For example, if you have provisioned a server with 250 gibibytes (GiB) of storage, then you have 250 GiB of backup storage capacity at no more charge. If the daily backup usage is 25 GiB, then you can have up to 10 days of free backup storage. Backup storage consumption that exceeds 250 GiB is charged as defined in the pricing model.
If you configured your server with geo-redundant backup, the backup data is also copied to the Azure paired region. So, your backup size will be twice the size of the local backup copy. Billing is calculated as ( (2 x local backup size) - provisioned storage size ) x price @ gigabytes per month.
You can use the Backup Storage Used metric in the Azure portal to monitor the backup storage that a server consumes. The Backup Storage Used metric represents the sum of storage consumed by all the retained database backups and log backups, based on the backup retention period set for the server.
Note
Irrespective of the database size, heavy transactional activity on the server generates more WAL files. The increase in files in turn increases the backup storage.
Point-in-time recovery
In Azure Database for PostgreSQL flexible server, performing a PITR creates a new server in the same region as your source server, but you can choose the availability zone. It's created with the source server's configuration for the pricing tier, compute generation, number of virtual cores, storage size, backup retention period, and backup redundancy option.
The physical database files are first restored from the snapshot backups to the server's data location. The appropriate backup that was taken earlier than the desired point in time is automatically chosen and restored. A recovery process then starts by using WAL files to bring the database to a consistent state.
For example, assume that the backups are performed at 11:00 PM every night. If the restore point is for August 15 at 10:00 AM, the daily backup of August 14 is restored. The database will be recovered until 10:00 AM of August 15 by using the transaction log backup from August 14, 11:00 PM, to August 15, 10:00 AM.
To restore your database server, see these steps.
Important
A restore operation in Azure Database for PostgreSQL flexible server always creates a new database server with the name that you provide. It doesn't overwrite the existing database server.
PITR is useful in scenarios like these:
- A user accidentally deletes data, a table, or a database.
- An application accidentally overwrites good data with bad data because of an application defect.
- You want to clone your server for test, development, or for data verification.
With continuous backup of transaction logs, you can restore to the last transaction. You can choose between the following restore options:
Latest restore point (now): This is the default option, which allows you to restore the server to the latest point in time.
Custom restore point: This option allows you to choose any point in time within the retention period defined for this Azure Database for PostgreSQL flexible server instance. By default, the latest time in UTC is automatically selected. Automatic selection is useful if you want to restore to the last committed transaction for test purposes. You can optionally choose other days and times.
Fast restore point: This option allows users to restore the server in the fastest time possible within the retention period defined for their Azure Database for PostgreSQL flexible server instance. Fastest restore is possible by directly choosing the timestamp from the list of backups. This restore operation provisions a server and simply restores the full snapshot backup and doesn't require any recovery of logs, which makes it fast. We recommend you select a backup timestamp, which is greater than the earliest restore point in time for a successful restore operation.
The time required to recover using the latest and custom restore point options varies based on factors such as the volume of transaction logs to process since the last backup and the total number of databases being recovered simultaneously in the same region The overall recovery time usually takes from few minutes up to a few hours.
If you configure your server within a virtual network, you can restore to the same virtual network or to a different virtual network. However, you can't restore to public access. Similarly, if you configured your server with public access, you can't restore to private virtual network access.
Important
Deleted servers can be restored. If you delete the server, you can follow our guidance Restore a dropped Azure Database for Azure Database for PostgreSQL - Flexible Server to recover. Use Azure resource lock to help prevent accidental deletion of your server.
Geo-redundant backup and restore
To enable geo-redundant backup from the Compute + storage pane in the Azure portal, see the quickstart guide.
Important
Geo-redundant backup can be configured only at the time of server creation.
After you configure your server with geo-redundant backup, you can restore it to a geo-paired region. For more information, see the supported regions for geo-redundant backup.
When the server is configured with geo-redundant backup, the backup data and transaction logs are copied to the paired region asynchronously through storage replication. After you create a server, wait at least one hour before initiating a geo-restore. That allows the first set of backup data to be replicated to the paired region.
Later, the transaction logs and the daily backups are asynchronously copied to the paired region. There might be up to one hour of delay in data transmission. So, you can expect up to one hour of RPO when you restore. You can restore only to the last available backup data that's available at the paired region. Currently, PITR of geo-redundant backups is not available.
The estimated time to recover the server RTO (recovery time objective) depends on factors like the size of the database, the last database backup time, and the amount of WAL to process until the last received backup data. The overall recovery time usually takes from a few minutes up to a few hours.
During the geo-restore, the server configurations that can be changed include virtual network settings and the ability to remove geo-redundant backup from the restored server. Changing other server configurations -such as compute, storage, or pricing tier (Burstable, General Purpose, or Memory Optimized)- during geo-restore is not supported.
For more information about performing a geo-restore, see the how-to guide.
Important
When the primary region is down, you can't create geo-redundant servers in the respective geo-paired region, because storage can't be provisioned in the primary region. Before you can provision geo-redundant servers in the geo-paired region, you must wait for the primary region to be up.
With the primary region down, you can still geo-restore the source server to the geo-paired region. For more information about performing a geo-restore, see the how-to guide. You should use Geo-replicas as your disaster recovery (DR) strategy if you need to configure DR to any region, or if the primary region doesn't support Geo-redundant backups
Restore and networking
Point-in-time recovery
If your source server is configured with a public access network, you can only restore to public access.
If your source server is configured with a private access virtual network, you can restore either to the same virtual network or to a different virtual network. You can't perform PITR across public and private access.
Geo-restore
If your source server is configured with a public access network, you can only restore to public access. Existing firewall rules in the source server are copied over to the restored server. Private endpoints are not taken over. After the restore operation is complete, review if you need to adjust any of the firewall rules carried over, and create any private endpoints you may need.
If your source server is configured with a private access virtual network, you can only restore to a different virtual network, because virtual networks can't span regions. You can't perform geo-restore across public and private access.
Post-restore tasks
After you restore the server, you can perform the following tasks to get your users and applications back up and running:
If the new server is meant to replace the original server, redirect clients and client applications to the new server. Change the server name of your connection string to point to the new server.
The values of all server parameters on the original server are not automatically applied to the new server. Ensure that all server parameters on the new server are re-configured as per the requirements of that new server.
Ensure that appropriate server-level firewall, private endpoints and virtual network rules are in place for user connections. In public access network, rules are copied over from the original server, but those might not be the ones required in the restored environment. So, adjust them as per your requirements. Private endpoints are not carried over. Create any private endpoints you may need in the restored server. In private access virtual network, the restore doesn't copy over any network infrastructure artifacts from source to restored server networks. Anything related to configuration of VNET(Virtual Network), subnets, or Network Security Groups, must be taken care of as a post-restore task.
Scale up or scale down the restored server's compute as needed.
Ensure that appropriate logins and database-level permissions are in place.
Configure alerts as appropriate.
If the source server from which you restored was configured with high availability, and you want to configure the restored server with high availability, you can then follow these steps.
If the source server from which you restored was configured with read replicas, and you want to configure read replicas on the restored server, you can then follow these steps.
On-demand Backups (preview)
Azure Database for PostgreSQL Flexible Server automatically generates storage volume snapshots of your entire database instance, covering all databases, as part of its scheduled backups. Additionally, you can create an on-demand backup whenever needed which is ideal for scenarios such as preparing for a potentially risky operation or performing periodic refreshes outside the usual backup schedule.
On-demand backups can be taken in addition to scheduled automatic backups. These backups are retained according to your backup retention window. You can delete these on-demand backups at any time if they are no longer needed. To initiate an on-demand backup, simply select the database instance you wish to back up and specify a backup name. These backups are stored alongside automated backups, but only on-demand backups can be deleted by users, as automated backups are managed and retained by the Flexible Server service to meet backup retention requirements.
For more information about performing an on-demand backup, visit the how-to guide.
Limitations
On-demand backup feature is currently not supported with the Burstable server compute tier.
Known Issues
We are aware of an existing bug that allows taking on-demand backups on Replicas, even though Point-in-Time Restore (PITR) is not supported in this context. This issue will be addressed to ensure that on-demand backups can only be performed on the Primary server.
Long-term retention (preview)
Azure Backup and Azure Database for PostgreSQL flexible server services have built an enterprise-class long-term backup solution for Azure Database for PostgreSQL flexible server instances that retains backups for up to 10 years. You can use long-term retention (LTR) independently or in addition to the automated backup solution offered by Azure Database for PostgreSQL flexible server, which offers retention of up to 35 days. Automated backups are physical backups suited for operational recoveries, especially when you want to restore from the latest backups. Long-term backups help you with your compliance needs, are more granular, and are taken as logical backups using native pg_dump. In addition to long-term retention, the solution offers the following capabilities:
- Customer-controlled scheduled and on-demand backups at the individual database level.
- Central monitoring of all operations and jobs.
- Backups are stored in separate security and fault domains. If the source server or subscription is compromised, the backups remain safe in the Backup vault (in Azure Backup managed storage accounts).
- Using pg_dump allows greater flexibility in restoring data across different database versions.
- Azure backup vaults support immutability and soft delete (preview) features, protecting your data.
- LTR backup support for CMK-enabled servers
Limitations and considerations
- LTR restores are currently available only as 'Restore as Files' to storage accounts, with 'Restore as Server' capability planned for the future.
- LTR backs up all databases in flexible server instances, and individual databases cannot be selected for LTR configuration.
- LTR backup is not supported on geo-replicas, but it can be performed from primary servers.
- The maximum supported database size for Long-Term Retention (LTR) backups is 4 TiB. While backups can be attempted on servers exceeding 4 TiB, these are not officially supported, and the success of LTR backups for such servers cannot be guaranteed.
- LTR backups can be scheduled weekly, monthly, or yearly. The daily backup schedule is currently unsupported.
For more information about performing a long term backup, visit the how-to guide.
Frequently asked questions
Backup-related questions
How does Azure handle backup of my server?
By default, Azure Database for PostgreSQL flexible server enables automated backups of your entire server (encompassing all databases created) with a default retention period of 7 days. The automated backups include a daily incremental snapshot of the database. The log (WAL) files are archived to Azure Blob Storage continuously.
Can I configure automated backups to retain data for the long term?
No. Currently, Azure Database for PostgreSQL flexible server supports a maximum of 35 days of retention. You can use manual backups for a long-term retention requirement using Azure Backup.
How do I manually back up my Azure Database for PostgreSQL flexible server instances?
You can manually take a physical snapshot using on-demand backup feature, you can also take logical backups using the PostgreSQL tool pg_dump. For examples, see Migrate your Azure Database for PostgreSQL flexible server database by using dump and restore.
What are the backup windows for my server? Can I customize them?
Azure manages backup windows, and you can't customize them. The first full snapshot backup is scheduled immediately after a server is created. Subsequent snapshot backups are incremental and occur once a day.
Are my backups encrypted?
Yes. All Azure Database for PostgreSQL flexible server data, backups, and temporary files that are created during query execution are encrypted through AES (Advanced Encryption Standard) 256-bit encryption. Storage encryption is always on and can't be disabled.
Can I restore a single database or a few databases in a server?
Restoring a single database or a few databases or tables is not directly supported. However, you can restore the entire server to a new server, and then drop tables or databases that you don't need on the new server.
Is my server available while a backup is in progress?
Yes. Backups are online operations that use snapshots. The snapshot operation takes only a few seconds and doesn't interfere with production workloads, to help ensure high availability of the server.
When I'm setting up the maintenance window for the server, do I need to account for the backup window?
No. Backups are triggered internally as part of the managed service and have no bearing on the maintenance window.
Where are my automated backups stored, and how do I manage their retention?
Azure Database for PostgreSQL flexible server automatically creates server backups and stores them in:
- Zone-redundant storage, in regions where multiple zones are supported.
- Locally redundant storage, in regions that don't support multiple zones yet.
- The paired region, if you configure geo-redundant backup.
These backup files can't be exported as they are stored in Microsoft-managed storage accounts. Customers have read-only access to restore these files but cannot modify or delete them. The backup files are automatically deleted after the retention period
You can use backups to restore your server to a point in time only. The default backup retention period is 7 days. You can optionally configure the backup retention up to 35 days.
With geo-redundant backup, how often is the backup copied to the paired region?
When the server is configured with geo-redundant backup, the backup data is stored in a geo-redundant storage account. The storage account copies data files to the paired region when the daily backup occurs at the primary server. WAL files are backed up when they're ready to be archived.
Backup data is asynchronously copied in a continuous manner to the paired region. You can expect up to one hour of delay in receiving backup data.
Can I do PITR at the remote region?
No. The data is recovered to the last available backup data at the remote region.
How are backups performed in a HA-enabled servers?
Data volumes in Azure Database for PostgreSQL flexible server are backed up through managed disk incremental snapshots from the primary server. The WAL backup is performed from either the primary server or the standby server.
How can I validate that backups are performed on my server?
The best way to check backups is to perform periodic PITR and ensure that backups are valid and restorable. Backup operations or files are not exposed to end users.
Where can I see the backup usage?
In the Azure portal, under Monitoring, select Metrics. In Backup Storage Used, you can monitor the total backup usage.
What happens to my backups if I delete my server?
If you delete a server, all backups that belong to the server are also deleted and can't be recovered. To help protect server resources from accidental deletion or unexpected changes after deployment, administrators can use management locks.
How are backups retained for stopped servers?
No new backups are performed for stopped servers. All older backups (within the retention window) at the time of stopping the server are retained until the server is restarted. After that, backup retention for the active server is governed by its retention window.
How will I be charged and billed for my backups?
Azure Database for PostgreSQL flexible server provides up to 100 percent of your provisioned server storage as backup storage at no extra cost. Any more backup storage that you use is charged in gigabytes per month, as defined in the pricing model.
The backup retention period and backup redundancy option that you select, along with transactional activity on the server, directly affect the total backup storage and billing.
How will I be billed for a stopped server?
While your server instance is stopped, no new backups are performed. You're charged for provisioned storage and backup storage (backups stored within your specified retention window).
Free backup storage is limited to the size of your provisioned database. Any excess backup data will be charged according to the backup price.
I configured my server with zone-redundant high availability. Do you take two backups, and will I be charged twice?
No. Irrespective of HA or non-HA servers, only one set of backup copies is maintained. You're charged only once.
Restore-related questions
How do I restore my server?
Azure supports PITR for all servers. Users can restore to the latest restore point or a custom restore point by using the Azure portal, the Azure CLI, and the API.
To restore your server from manual backups by using tools like pg_dump, you can first create an Azure Database for PostgreSQL flexible server instance and then restore your databases to the server by using pg_restore.
Can I restore to another availability zone within the same region?
Yes. If the region supports multiple availability zones, the backup is stored on a zone-redundant storage account so that you can restore to another zone.
How long does a PITR take? Why is my restore taking so much time?
The data restore operation from a snapshot doesn't depend on the size of data. But the recovery process timing that applies the logs (transaction activities to replay) might vary, depending on the previous backup of the requested date/time and the number of logs to process. This applies to both restoring within the same zone or and restoring data to a different zone.
If I restore my HA-enabled server, is the restore server automatically configured with high availability?
No. The server is restored as a single-instance Azure Database for PostgreSQL flexible server instance. After the restore is complete, you can optionally configure the server with high availability.
I configured my server within a virtual network. Can I restore to another virtual network?
Yes. At the time of restore, choose a different virtual network to restore to.
Can I restore my public access server to a virtual network or vice versa?
No. Azure Database for PostgreSQL flexible server currently doesn't support restoring servers across public and private access.
How do I track my restore operation?
Currently, there's no way to track the restore operation. You can monitor the activity log to see if the operation is in progress or complete.
Share your suggestions and bugs with the Azure Database for PostgreSQL product team.