How MCMS file upload works:
When a file is uploaded, MCMS adds and saves them to the database. Once in the DB, it gets cached on the file system when there is a request for it.
What happens when we rename / delete the file in file cache :
When we remove/delete the cached file (the one in RdOnlyRes), we are manually breaking the coordination between the CMS memory node cache and the file cache. When it is cached on the file system, CMS also maintains a memory node cache saying that "this" file is cached on the file system. So that any subsequent request on that resource, cms won't go to the database to grab but serve it from the file system (disk cache). When we modify the file or delete the file ( as we tried in the disk cache), CMS memory node cache is not aware of this. So it will try to find the file in file cache which is not there. So, in that case it will throw 404 error.
File deletion Problem:
So what happens if the files in file cache are deleted ? In this case, to cache the files again in file cache, we need to restart the services. Once services are restarted, CMS will once again cache the files. Please note , first time in this case will be slow as it needs to get the files from database.
What needs to be done:
Stop IISAdmin service. Then stop and start aesecurityservice( CMS service ). Then start iisadmin and w3svc services. After doing this, the files will be once again cached and the documents will be shown as expected.
PingBack from http://microsoft-sharepoint.simplynetdev.com/understanding-mcms-file-cache/