Almost Always Add Swap Space
I was hoping this post was going to say something like turning on some small amount of swap will allow the OS to cache some things that normally it wouldn&#x27;t cache at all, and so you get some improvement there.  What&#x27;s actually in this post doesn&#x27;t make any sense to me.  If I have enough RAM why do I want things to swap to begin with?  The author never explained why putting rarely used pages in swap will improve performance if I have adequate RAM.<p>And using swap as some kind of &quot;RAM emergency cover&quot; does not make any sense to me.  Personally, I have never had a case where I could gracefully recover a host that had started swapping.<p>First, my production servers are not doing many other things besides being production servers.  It&#x27;s not like they are running a bunch of unnecessary services, and if I kill some then my application can recover.  If a process is out of control then it&#x27;s almost assuredly something important that I&#x27;m going to have to kill anyway.<p>Second, I find it&#x27;s much harder to detect degraded performance than it is to detect a dead process.  It&#x27;s very, very easy to have a health check that will detect a host who has stopped listening and drop that host from the LB.  And alerting on that scenario is very easy as well.  The alternative is a host that&#x27;s operating in a degraded state, which I need to detect with more sophisticated health check + alerting, and in the end my resolution is just going to be to kill everything anyway.<p>In a properly designed HA environment the loss of a host should be no big deal.  Architecture should be focused on making sure a host goes down ASAP if it&#x27;s having problems, not letting it survive in some kind of zombie state.