Nicola Contu wrote: > we are running Postgres 10.5 with master slave replication. > > This server is on Centos 7 and the strange thing is that we see a lot of swap usage : > > [root@usnyh-cmd1 ~]# free -m > total used free shared buff/cache available > Mem: 257652 7555 5559 12804 244536 236036 > Swap: 16383 7326 9057 > > 7GB used. > > But can't see it from any of the commands like top etc. > I am sure it is postgres because it is the only service running on that machine. > > Is there anything we can do? > On the sync slave, the usage is just 400MB. I recommend that you set "vm.swappiness = 0" using "sysctl" to discourage the operating system from swapping as much as possible. Yours, Laurenz Albe -- Cybertec | https://www.cybertec-postgresql.com