NFS Directories between 2 Servers
To prevent synchronization issues, you should mount the files directory as a shared folder over NFS between the drupal webservers, so that each Drupal instance has a symlink to the same file share

e.g:

/var/www/drupal-site-mysite/sites/default/files -&gt; /var/lib/sitedata/drupal-site-mysite/files

where /var/lib/sitedata/drupal-site-mysite/files is a NFS mount/share.