Huge problem loading pages
Got 4 linodes in the London data center, 2 app boxes (apache/php etc.), 1 database server and 1 email server. Started yesterday, one of the app servers running CentOS 7 started to run really slow. Linode manager shows everything okay when it comes to CPU, IO etc. Nagios is used to monitor and nothing looks odd. TOP shows close to no activity for CPU/load but a web page hosted on it takes about 60 seconds to load. This just "happend", haven't don't anything to the box nor the website.
The website have a database on the DB server, communicating over LAN, ping is normal etc.
Have no idea where to start to look. At first I thought it was something temporary, but now after 15 hours still the same issue. Can someone please point me in the right direction?
Output from "top" on the said server:````
top - 23:36:16 up 108 days, 2:44, 1 user, load average: 0.01, 0.01, 0.00
Tasks: 208 total, 1 running, 207 sleeping, 0 stopped, 0 zombie
%Cpu(s): 1.2 us, 0.3 sy, 0.0 ni, 98.5 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 8.7/12300388 [ ]
KiB Swap: 0.0/524284 [ ]
Ping from the web server to database server:````
[foo@bar-new ~]$ ping xxx.yyy
PING mysql1.domain.tld (xxx.yyy.zzz) 56(84) bytes of data.
64 bytes from mysql1.domain.tld (xxx.yyy.zzz): icmp_seq=1 ttl=64 time=0.553 ms
64 bytes from mysql1.domain.tld (xxx.yyy.zzz): icmp_seq=2 ttl=64 time=0.643 ms
64 bytes from mysql1.domain.tld (xxx.yyy.zzz): icmp_seq=3 ttl=64 time=0.605 ms
64 bytes from mysql1.domain.tld (xxx.yyy.zzz): icmp_seq=4 ttl=64 time=0.553 ms
64 bytes from mysql1.domain.tld (xxx.yyy.zzz): icmp_seq=5 ttl=64 time=0.608 ms
64 bytes from mysql1.domain.tld (xxx.yyy.zzz): icmp_seq=6 ttl=64 time=0.643 ms
Thanks!