Adie asked:
I have a problem with new server.. I use VPS Centos with 1GB of ram and I use wordpress CMS.
The traffic <100 visitor/hour, but the apache have high load and make the server hang with zero free of ram and can’t connect through ssh. I should reboot the vps to make it works
here is the load on Apache looks like
Tasks: 66 total, 1 running, 65 sleeping, 0 stopped, 0 zombie
Cpu(s): 1.6%us, 12.3%sy, 0.0%ni, 48.1%id, 23.0%wa, 4.8%hi, 10.2%si, 0.0%
Mem: 1018776k total, 116620k used, 902156k free, 1236k buffers
Swap: 1048568k total, 1013052k used, 35516k free, 26628k cached
2949 apache 20 0 459m 42m 3732 D 3.0 4.2 0:09.23 httpd
2959 apache 20 0 460m 29m 3744 D 2.0 3.0 0:02.72 httpd
2968 apache 20 0 460m 26m 3808 D 2.0 2.6 0:02.27 httpd
2972 apache 20 0 460m 24m 3784 D 2.0 2.5 0:02.44 httpd
2986 apache 20 0 460m 29m 3784 R 2.0 2.9 0:02.40 httpd
2969 apache 20 0 458m 29m 3864 D 1.6 3.0 0:02.63 httpd
2974 apache 20 0 460m 25m 3820 D 1.6 2.6 0:02.43 httpd
2990 apache 20 0 460m 23m 3920 D 1.6 2.4 0:02.36 httpd
2994 apache 20 0 460m 31m 3756 D 1.6 3.2 0:02.62 httpd
2956 apache 20 0 460m 26m 3740 D 1.3 2.7 0:02.73 httpd
2957 apache 20 0 465m 22m 3644 D 1.3 2.3 0:02.80 httpd
2967 apache 20 0 458m 24m 3764 D 1.3 2.5 0:02.60 httpd
2970 apache 20 0 463m 25m 3764 D 1.3 2.6 0:03.07 httpd
2971 apache 20 0 451m 22m 3792 D 1.3 2.3 0:02.47 httpd
2973 apache 20 0 458m 25m 3768 D 1.3 2.6 0:02.52 httpd
2987 apache 20 0 465m 20m 3772 D 1.3 2.1 0:03.02 httpd
But sometimes the server have uptime more than 5-10hrs but after that the problems start
My answer:
Congratulations, you’ve managed to use nearly all of your swap space.
The first obvious problem here is that you went very deep into swap. This is probably what’s causing the system to thrash so hard (lots of time spent in system, I/O wait and software interrupts). It looks like you killed some processes before this top output, though, so some memory was freed up.
First thing to do is to reduce the number of Apache processes that are running. You don’t need that many for a small site, and it’s just going to throw you deep into swap and kill your performance…which is what already happened. I would recommend you start very small and increase when it becomes necessary. An example:
StartServers 4
MinSpareServers 4
MaxSpareServers 10
MaxClients 25
This limits you to only serving 25 simultaneous requests (everyone else has to wait in line). But you are very unlikely to hit that unless your blog suddenly winds up on the front page of reddit or something. And if you expect that to happen on a regular basis, you need a bigger server and a professional sysadmin on call.
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