A while ago I needed to share the same copy of some large files between several server instances. It needed to be the same actual file, and synced instantly - ruling out the use of hacky solutions like rsync'ing files via a cron job etc.
It turns out this isn't too difficult to do with NFS, which lets you nominate a folder on a master server which can be accessed by one (or more) client servers.
Here's how to do this, using CentOS servers:
# Set NFS file sharing between servers (Run on master server) yum install nfs-utils nfs-utils-lib chkconfig nfs on # Edit /etc/exports to enable the /var/www/mydomain/shared folder to be shared with client servers at these IP addresses /var/www/mydomain/shared 18.104.22.168(rw,sync,no_root_squash,no_subtree_check) /var/www/mydomain/shared 22.214.171.124(rw,sync,no_root_squash,no_subtree_check) # edit /etc/sysconfig/nfs and uncomment the following lines RQUOTAD_PORT=875 LOCKD_TCPPORT=32803 LOCKD_UDPPORT=32769 MOUNTD_PORT=892 STATD_PORT=662 STATD_OUTGOING_PORT=2020 # Setup NFS on client server yum install nfs-utils nfs-utils-lib /etc/init.d/nfs start chkconfig nfs on mkdir -p /path/to/where/to/mount mount -t nfs 126.96.36.1996:/var/www/mydomain/shared/ /path/to/where/to/mount/ # add the following lines to /etc/fstab (client server only) to automount every reboot 188.8.131.526:/var/www/mydomain/shared nfsrw,sync,hard,intr 0 0