We use piwik since 2009 and we are very happy with it, it is an awsome platform, congratulations an thank you for it.
Today we have detected a problem with our installation, since 18 February we have files at our root folder with more or less 250MB.
All files name start with core.* (a number), example: core.2780.
The system is working with no problems or errors reported but we know have 143 files with the core.* and 34GB of disk space occupied for it.
Can you guys help us? What are those files? Can we delete it or are they normal?
Is it related with the auto archive option? (we have about 50 sites, 3 of them no more than 10k visits/day)
Thank you in advance.