I'm wondering how large sites like StackOverflow handle their access logs. A write to the disk on every request seems a little bit uneconomical, but is Google Analytics that reliable to use it as your only information resource?
There is much information that web server logs contain which will never be available to Google Analytics, two things I can think of:
- Errors like 404, etc.
- Access on media files, like pictures, etc. (including external websites linking to your images)
- IP addresses, although an answer to another question pointed out that it can be set as a user variable
- Full length referral URLs, for example Google sends links from product search, web search, etc. each search has keywords but Google Analytics does not display the other variables like
Must be more stuff I just can't think of right now.
And there are also the error logs; must be important for a website to run smoothly, in my opinion. Not something you would ignore.
I don't really look at these logs and end up deleting them on a monthly basis. I only look at them for trouble shooting. As for as monitoring application use Google Analytics, CrazyEgg and others do a great job.
Before such services existed these logs were very valuable. Now, they are good developer tools, but I don't know of any of my colleagues or friends that actively archive these logs or parse them for data.