Log Shipping Servers
For every PostgreSQL VM whose WAL files you want to back up, Veeam Backup & Replication defines how to ship logs to the backup repository. WAL files can be transported in the following ways:
- Directly from the VM guest OS to the backup repository. This method is recommended — it does not involve additional resources and puts less load on the VM guest OS.
- Via log shipping servers. If it is not possible to establish a direct connection between the VM guest OS and backup repository, you can configure Veeam Backup & Replication to use a log shipping server.
A log shipping server is a Linux server added to the backup infrastructure. You can explicitly define what servers you want to use for log shipping or instruct Veeam Backup & Replication to automatically choose an optimal log shipping server. Depending on the possible data transfer methods and location of the PostgreSQL VM and the log shipping server, Veeam Backup & Replication chooses the log shipping server.
Data Transfer Methods
Log shipping servers can transport data in two ways:
- Over the network. In this scenario, Veeam Backup & Replication obtains files from the VM guest OS and transfers them over the network. This is a default method that uses log shipping servers.
- Over PowerShell Direct. In this scenario, Veeam Backup & Replication obtains WAL files from the VM guest OS over PowerShell Direct, bypassing the network. PowerShell Direct is used for VMs that reside on Microsoft Hyper-V Server 2016 (or later) and run Microsoft Windows 10 (or later) or Microsoft Windows Server 2016 (or later). Veeam Backup & Replication requires Microsoft PowerShell 2.0 (or later) to work over PowerShell Direct.
Location of Log Shipping Server and VMs
When choosing a log shipping server for the job, Veeam Backup & Replication considers the location of the PostgreSQL VM and log shipping server. Veeam Backup & Replication uses the following priority rules to select the log shipping server:
- The log shipping server is located on the source Microsoft Hyper-V host performing the role of the on-host backup proxy.
- The log shipping server and PostgreSQL VM are located in the same network.
- The log shipping server and PostgreSQL VM are located in different networks (the production infrastructure is isolated from the backup infrastructure).
That is, when choosing a log shipping server, Veeam Backup & Replication will give the top priority to a VM that is located on the source Microsoft Hyper-V host.
Veeam Backup & Replication assigns log shipping servers per job session. When a new job session starts, Veeam Backup & Replication detects a new log shipping servers. Veeam Backup & Replication can also re-detect available servers during the job session. If the log shipping server becomes unavailable for some reason, Veeam Backup & Replication will fail over to another log shipping server.
If you do not want to use some servers for WAL files transport, you can manually define what server Veeam Backup & Replication must use as a log shipping server in the job settings. It is recommended that you assign the log shipping server role to a number of servers for availability purposes.