Pi2 freeze randomly, how to find the cause?

[allan163]

My Pi2 connects to a rounter by LAN, and powered by a SAMSUNG 2A charger. I access my Pi2 by ssh usually. It works perfectly until recently. My pi freezes(or down, or crash, I don't know) randomly. When this happens, ssh to pi failed, ping failed, only the red LED was on(no flash, green LED is off). I have to plugin off and on the power to restart my pi to make it work. This happened several times, during the day, during night, even during I'm using it by ssh(only less than two hours after I restart my pi).

I tried to locate the cause by my self, I read nearly all log files under /var/log, but have found no clue.
please someone tell me how to debug this problem? I can't connect my pi to a monitor because it is too far away from my desk.

[allan163]

Can any one help?

[Canedje]

Nothing to do with a corrupted sd-card?

(I had sometimes reboot problems because bad contacts of de sd card)

[allan163]

I used "dd" to test my SD-Card, it seems normal, read speed is about 13MB/s, write speed is about 3MB/s .

I run a wordpress blog on my Pi2, it is very strange that when I access my blog, CPU load of Pi2 can raise to 70 to 80%(is it normal?). It seems the freeze has something to do high CPU load. my last two freeze happened just when I was access my blog doing some modification