But, that is a question of 2008 and still remains unanswered on the httpd mailing list.
I am trying to share a NFS mount between two physical machines running mod_cache_disk module, so that both machines should be able to share the cached data. These two cache servers are behind a load balancer which routes incoming requests in round-robin fashion.
The mounts were owned by "cacheUser" and this user has read/write permissions to mounted directory. Also, the running process of httpd was owned by the same user "cacheUser".
After a lot of investigation, I found out, that the code in file "mod_cache_disk.c" has logic as below:
This snippet belongs to function open_entity().
/* Atomic check - does the body file belong to the header file? */
if (dobj->disk_info.inode == finfo.inode &&
dobj->disk_info.device == finfo.device) {
/* Initialize the cache_handle callback functions */
ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(00709)
"Recalled cached URL info header %s", dobj->name);
/* make the configuration stick */
h->cache_obj = obj;
obj->vobj = dobj;
return OK;
}
I believe, checking the inode prevents different machines to share the same data over NFS. Also, the device ID for mounted folder changes.
Hence, this check fails.
And I get error in log which is part of this code section :-
/* Oh dear, no luck matching header to the body */
ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(00710)
"Cached URL info header '%s' didn't match body, ignoring this entry",
dobj->name);
I would like to know what is the reason behind using this logic of checking the inode instead of the actual contents?
Regards,
Akshay Patil
