Krutik Jayswal Thanks, but my permissions are fine (permissions are set to the tomcat7 user, as they should be).
I belive the issue is related to the following discussions:
Quote from REPO-4512:
The current alfresco.log configuration is stored inside the war file, see.
The configuration creates the alfresco.log in the base directory, which is often Tomcat root. This contradicts with security best practices around file permissions which require Tomcat root to be read only. Note that overrides in the custom-log4j.properties does not solve this issue.
One has to modify the internals of the war file (log4j.properties) and specify the correct path to the logs folder to mitigate this issue.It is bad practice to modify the internals of the war file.
but I am unable to understand the conclusion or to find a fix.