[CentOS] Effectiveness of CentOS vm.swappiness

Fri Jun 5 19:21:43 UTC 2015
Markus "Shorty" Uckelmann <shorty at koeln.de>

Am 05.06.2015 um 17:40 schrieb Greg Lindahl:
> On Fri, Jun 05, 2015 at 12:29:04PM +0200, Markus "Shorty" Uckelmann wrote:
>
>> How can I further debug this
>> problem and find out what's the culprit?
>
> It's working as designed.

Sadly. It is just my first time I see this behaviour to this extent/on 
so many servers. So you can say that I'm kind of a newbie in swapping ;)

> If you don't explicitly lock things into memory, file I/O can and will
> cause idle pages to get pushed out. It happens less often if you
> manipulate swappines.

So, is a swappiness value of 60 not recommended for servers? I worked 
with hundreds of servers (swappiness 60) on a social platform and 
swapping very rarely happened and then only on databases (which had 
swappiness set to 0). The only two differences (that I can see) to my 
current servers are that I used Debian and there was no "extra" I/O from 
backups.

I might be overstating the swapping thing. That's what I'm trying to 
find out.

Cheers, Shorty