In Google Cloud Memorystore Redis Standard, can a read replica be promoted to master?

Can a read replica become master/primary (with automatic or manual promotion) in Google Cloud Memorystore Redis Standard?

If so:

• How do I did this?
• Why do they present High Availability as a separate feature, when read-replicas could just serve this purpose?

Yes, The read replica can be promoted to master/primary in Google Cloud Memorystore Redis Standard. This process is known as the failover. It can be achieved either Automatically or manually. For more information about the failover you can refer to the documents Failovers for instances with read replicas and Manual Failover. You can follow the process of manual failover initiation which is documented here Initiate a manual failover.

High availability (HA) is the ability of a system to operate continuously for a designated period of time even if components within the system fail. Failover is a means of achieving high availability (HA). The difference between the HA and the Failover is explained in the StackOverflow case

As per the document Memorystore for Redis provides high availability by replicating a Redis primary to one or more replicas . The HA is not a separate feature in the memorystore. On selecting the read replica in the Memorystore for Redis instance, the HA is enabled. Additionally,if you don’t want a replica for your instance you can select the No read replicas (high availability only) configuration . For more details you can follow Redis tier capabilities which explains the details about the different tiers of the memorystore.