An improved scalable object storage system includes methods and systems allowing multiple clusters to work together. In one embodiment, there is a multi-cluster synchronization system between two or more clusters. The multi-cluster synchronization system uses variable compression to optimize the transfer of information between the clusters. Compression is used not only to minimize the total number of bytes sent between the two clusters, but to dynamically vary the size of the objects sent across the wire to optimize for higher throughput after considering packet loss, TCP windows, and block sizes. This includes both the packaging of multiple small files together into one larger compressed file, saving on TCP and header overhead, but also the chunking of large files into multiple smaller files that are less likely to have difficulties due to intermittent network congestion or errors.