Is it possible to put the server with an incorrect request?

Question

Nginx

Today our server was a little feverish, even fell down for a while and did not respond to requests
. There is such a thing in the logs

2016/08/09 14:25:12 [error] 17959#17959: *1644668 open() "/var/mysite/wp-content/uploads/2014/08/1-дтп-знак-среднее-увага-дтп-342x225.jpg" failed (2: No such file or directory), client: 127.0.0.1, server: www.mysite.ua, request: "GET /wp-content/uploads/2014/08/1-%D0%A0%D2%91%D0%A1%E2%80%9A%D0%A0%D1%97-%D0%A0%C2%B7%D0%A0%D0%85%D0%A0%C2%B0%D0%A0%D1%94-%D0%A1%D0%83%D0%A1%D0%82%D0%A0%C2%B5%D0%A0%D2%91%D0%A0%D0%85%D0%A0%C2%B5%D0%A0%C2%B5-%D0%A1%D1%93%D0%A0%D0%86%D0%A0%C2%B0%D0%A0%D1%96%D0%A0%C2%B0-%D0%A0%D2%91%D0%A1%E2%80%9A%D0%A0%D1%97-342x225.jpg HTTP/1.1", host: "www.mysite.ua"
2016/08/09 14:25:12 [error] 17959#17959: *1644668 open() "/var/mysite/wp-content/uploads/2014/08/1-дтп-знак-среднее-увага-дтп.jpg" failed (2: No such file or directory), client: 127.0.0.1, server: www.mysite.ua, request: "GET /wp-content/uploads/2014/08/1-дтп-знак-среднее-увага-дтп.jpg HTTP/1.1", host: "www.mysite.ua"
2016/08/09 14:25:12 [error] 17959#17959: *1644668 open() "/var/musite/wp-content/uploads/2014/08/1-дтп-знак-среднее-увага-дтп-342x225.jpg" failed (2: No such file or directory), client: 127.0.0.1, server: www.mysite.ua, request: "GET /wp-content/uploads/2014/08/1-дтп-знак-среднее-увага-дтп-342x225.jpg HTTP/1.1", host: "www.mysite.ua"

after which there are no logs at all for about 40 minutes
Server on Ubuntu 12.04.5
Where to dig? How to protect yourself from this in the future?

Answer 1

Only errors go to the error log - so there are breaks in the logs for a couple of days

fell off briefly

loose concept

Answer 2

It’s better to look in access.log, the fact that you have 404 errors in the log every few days doesn’t mean anything, it’s much more difficult for the server when php scripts get to the existing paths.
See access.log for very frequent requests from one ip, sites are often attacked by inadequate robots that pull 20 pages per second... Fell down for a
while and did not respond, probably ran into the processor or IO (disk), ran out of RAM or mysql pondered from heavy requests.
How to protect yourself? Cache responses, load test the site and the server, optimize the scripts themselves