PostgreSQL-12.1 :: Streaming Replication Error - database-backups

Question

I have set up streaming replication on PostgreSQL 12.1
The master and slave are configured as below and WAL files are accumulating on the master.
However, something is wrong as I get complaints that the WAL files are missing after a pg_restore on MASTER
MASTER
postgres#srvm:~$ 2019-12-20 16:35:07.910 CET [1334] replicator#[unknown] ERROR: requested WAL segment 000000010000000100000076 has already been removed
2019-12-20 16:35:12.920 CET [1338] replicator#[unknown] ERROR: requested WAL segment 000000010000000100000076 has already been removed
2019-12-20 16:35:17.925 CET [1340] replicator#[unknown] ERROR: requested WAL segment 000000010000000100000076 has already been removed
2019-12-20 16:35:22.932 CET [1362] replicator#[unknown] ERROR: requested WAL segment 000000010000000100000076 has already been removed
2019-12-20 16:35:27.935 CET [1364] replicator#[unknown] ERROR: requested WAL segment 000000010000000100000076 has already been removed
2019-12-20 16:35:32.942 CET [1365] replicator#[unknown] ERROR: requested WAL segment 000000010000000100000076 has already been removed
2019-12-20 16:35:37.948 CET [1366] replicator#[unknown] ERROR: requested WAL segment 000000010000000100000076 has already been removed
2019-12-20 16:35:42.954 CET [1367] replicator#[unknown] ERROR: requested WAL segment 000000010000000100000076 has already been removed
SLAVE
postgres#srvs:~$ 2019-12-20 16:36:53.027 CET [21978] LOG: started streaming WAL from primary at 1/76000000 on timeline 1
2019-12-20 16:36:53.027 CET [21978] FATAL: could not receive data from WAL stream: ERROR: requested WAL segment 000000010000000100000076 has already been removed
2019-12-20 16:36:58.029 CET [21979] LOG: started streaming WAL from primary at 1/76000000 on timeline 1
2019-12-20 16:36:58.029 CET [21979] FATAL: could not receive data from WAL stream: ERROR: requested WAL segment 000000010000000100000076 has already been removed
2019-12-20 16:37:03.040 CET [21980] LOG: started streaming WAL from primary at 1/76000000 on timeline 1
2019-12-20 16:37:03.040 CET [21980] FATAL: could not receive data from WAL stream: ERROR: requested WAL segment 000000010000000100000076 has already been removed
2019-12-20 16:37:08.042 CET [21981] LOG: started streaming WAL from primary at 1/76000000 on timeline 1
2019-12-20 16:37:08.042 CET [21981] FATAL: could not receive data from WAL stream: ERROR: requested WAL segment 000000010000000100000076 has already been removed
Then the pg_basebackup is run and the slave started.
The slave has all the data as of the time of the backup, but no new data from the WAL files, and the error above.
max_wal_senders = 10
wal_keep_segments = 120
What have I mis-configured? Do we need to enabled archive_mode = on for streaming replication?

Answer 1

Here is my configuration for streaming replication:
Master config
listen_addresses = 'localhost,[IP_ADDRESS_OF_PRIMARY_ON_LAN]' # what IP address(es) to listen on;
wal_level = 'replica'
archive_mode = on
archive_command = 'cd .'
max_wal_senders = 5
primary_conninfo = 'host=[REPLICA_IP] port=5432 user=replication password=[REPLICATION PASSWORD]'
hot_standby = on
max_wal_senders = 10
wal_keep_segments = 48
Slave config:
listen_addresses = 'localhost,[IP_ADDRESS_OF_REPLIACA_ON_LAN]' # what IP address(es) to listen on;
max_connections = 100 # Ensure that this value is the same as the primary's
wal_level = 'replica'
archive_mode = on
archive_command = 'cd .'
max_wal_senders = 5
primary_conninfo = 'host=[PRIMARY_IP] port=5432 user=replication password=[REPLICATION PASSWORD]'
hot_standby = on
max_wal_senders = 10
wal_keep_segments = 48
I set up my server using the following resource: https://www.gab.lc/articles/postgresql-12-replication/