rsync is perfect for small, incremental syncs. But at petabyte scale and over distance it is single-stream — one TCP connection that leaves most of your bandwidth idle. Zettar moves the same data in parallel at line rate, turnkey.
rsync was built for incremental file sync on one machine, not petascale movement across sites and clouds. At scale it runs a single stream, so a 100 Gbps link delivers a fraction of its capacity — and a failed run often restarts from scratch. Teams paper over it with hand-sharded scripts and parallel-rsync wrappers that become a maintenance burden of their own.
| rsync / scp | Zettar zx | |
|---|---|---|
| Parallelism | Single stream, one connection | Massively parallel, scale-out |
| Realized bandwidth | A fraction of a fast link | ~90%+ — line rate |
| Petascale | Stalls; needs hand-sharded scripts | 1 PB in 29 hours, proven |
| Long distance (WAN) | Throughput collapses with latency | Distance-insensitive (12,375 mi tested) |
| Failure & resume | Often restarts the transfer | Self-healing, checkpointed |
| Integrity & encryption | Manual / add-on | End-to-end checksums + TLS, built in |
| Operating model | DIY scripts you build and maintain | Turnkey appliance, supported as one |
rsync is free and excellent for what it was built for. The cost shows up at scale — in the engineering time to shard and babysit it, and in the bandwidth you pay for but never fill.
The Zettar zx Appliance is co-designed across storage, host, network, and software to run in parallel at line rate — roughly 10× typical movers, with no software ceiling. It ships pretuned on the enterprise hardware you choose and is supported as one solution. With SLAC and the U.S. DOE it moved 1 PB in 29 hours at 96% link utilization — and won the Supercomputing Asia 2019 Data Mover Challenge.
Compare Zettar with: rsync · Globus · Aspera / Signiant
It replaces rsync where rsync stalls — large-scale, cross-site, and cloud movement, where a single stream cannot fill a fast link. For small local syncs rsync is fine; for petascale and long distance the zx Appliance runs massively parallel at line rate, supported as one turnkey solution.
Roughly 10x typical movers, because speed is utilization, not raw bandwidth: rsync's single stream fills a fraction of a fast link while zx runs in parallel at about 90%+ line rate. With SLAC and the U.S. DOE it moved 1 PB in 29 hours at 96% utilization.
You can shard and wrap rsync, but that becomes a brittle DIY project to build, tune, and maintain — and it still lacks self-healing, built-in end-to-end integrity, and one accountable support path. zx delivers parallel line rate turnkey.
Bring your hardest transfer — we’ll show you what line rate does for it, measured on your data.