Checks After Failover Setup
Check Email is Flowing
On (all) the scanner(s) run the following:
tail -f /var/log/mail-daily/current.log
It should be obvious if mail is flowing.
Checking WAL File Streaming
You can check if WAL data is streaming by running on the primary this command:
watch -d 'ps auxww|grep [s]treaming'
You will see something like this:
postgres 25972 0.2 0.1 103012 4912 ? Ss 15:24 0:09 postgres: wal sender process postgres 192.168.190.120(54248) streaming 26E/6A01AEF0
Where the last few hex digits will be changing if things are okay. (They will change fast on a busy system and possibly very slowly on a lightly-loaded one.)
On the backup database run:
watch -d 'ps auxww| grep "[p]ostgres: startup"
You should see something like:
postgres 39942 0.0 0.6 101408 27488 ? Ss 15:23 0:02 postgres: startup process recovering 000000070000026E0000006A
Where the last few digits change over very slowly over several minutes. This shows WAL files being consumed.