A method performed at a computing device, the computing device having one or more processors and storage media storing one or more programs, the one or more programs including instructions configured to perform the method, the computing device communicatively coupled to a peer computing device via at least a first data communications network, comprising: receiving (212, 708, 1408), from the peer computing device (110-1, 110-2), a peer download advertisement, the peer download advertisement comprising an identifier of a content item namespace (314, 414) and a client journal cursor value, wherein the client journal cursor value reflects a synchronization state of the content item namespace with regard to the peer computing device; wherein the client journal cursor value is specific to the content item namespace and is specific to the peer computing device; wherein the content item namespace comprises a collection of content items under management of an online content management service; receiving (218, 712, 1412), from a metadata server of the online content management service, an identification of content item blocks and an associated server journal cursor value, the content item blocks making up a content item, wherein the computing device and the metadata server are communicatively coupled via at least a second data communications network, wherein the second data communications network does not include the first data communications network; and based, at least in part, on the received client journal cursor value and the received server journal cursor value, identifying (218, 714, 1416) and downloading (220, 716, 1418), from the peer computing device, one or more content item blocks, of the content item blocks making up the content item, that are stored at the peer computing device. receiving (212, 708, 1408), from the peer computing device (110-1, 110-2), a peer download advertisement, the peer download advertisement comprising an identifier of a content item namespace (314, 414) and a client journal cursor value, wherein the client journal cursor value reflects a synchronization state of the content item namespace with regard to the peer computing device; wherein the client journal cursor value is specific to the content item namespace and is specific to the peer computing device; wherein the content item namespace comprises a collection of content items under management of an online content management service; receiving (218, 712, 1412), from a metadata server of the online content management service, an identification of content item blocks and an associated server journal cursor value, the content item blocks making up a content item, wherein the computing device and the metadata server are communicatively coupled via at least a second data communications network, wherein the second data communications network does not include the first data communications network; and based, at least in part, on the received client journal cursor value and the received server journal cursor value, identifying (218, 714, 1416) and downloading (220, 716, 1418), from the peer computing device, one or more content item blocks, of the content item blocks making up the content item, that are stored at the peer computing device.