How can I use grav CMS on a shared server which log directory is not writeable?

Hi, after I tested my website locally, I have an issue to run grav cms on a shared server because the htdocs/logs is not writeable.
The eeror message:
/homepages/6/d505144961/htdocs/logs exists but is not writeable.
How can I solve this?

It's a permission issue. Check the webserver can write to the logs folder, see the learn site for more info on permissions.

the system admin cannot change the permission access in logs directory :(. But he said that I shall write the CMS log into another directory such as logsgrav/. How can I change this setting?

This is actually something that we are going to add shortly (hopefully for Grav 1.1 release). We already have an issue for it - https://github.com/getgrav/grav/issues/715