Why Linux swappines is so high while HDD is slower than RAM?

[postcd]

Why linux default (i have Redhat CenOS) swappiness (http://en.wikipedia.org/wiki/Swappiness) value is 60 (to rather use disc than RAM?) while HDD is slower than RAM?
Why it is not like lets say 30 ? or closest to zero as possible?

(i have linux webserver)

 

[Yesyesloud]

CentOS is a server-oriented distribution, virtual memory is very important for those machines (specially when server activity is intense). Regardless, you can set swappiness according to your needs.

Also, despite page files exist in order to allow a machine to behave as if it had extra memory, swappiness is a bit more complex than the fact that storage is slower than RAM. Some people report to have better performance when swappiness is, say, high.

Anyway, I set my laptop swappiness to 10 and I'm glad with it.