Mac OS X supports a fairly rich set of metadata and permissions data, and in some cases you may not be able to preserve it on remote systems. This can happen because a system fundamentally doesn’t support a given technology, or for security reasons, like a remote system not giving you privileges to set particular attributes.
In most cases, that’s not a particularly big problem, as metadata is generally nonessential, and sending data to a server with intentionally varying permissions info is quite rare and only happens to fairly sophisticated users. As a result, Synk by default handles these types of attributes on a “best effort” basis, but Synk Pro allows you to alternatively choose to make them mandatory in a copy or ignored entirely.
Each attribute type (ACLs, xattrs, and ownership) can have one of three policies: