How long will that backup take?
The first cloud backup is the one that hurts: upload speeds are usually a fraction of download speeds.
50% of 1 TB by posting a disk
24 h is longer than 2 of the 5 references on this page.
Reference figures are measurements and are rounded; the unit conversion behind them is exact.
| Reference | Size | Yours ÷ theirs | Note |
|---|---|---|---|
| 1 TB to an external USB drive | 0.833 h | 28.8× | Under an hour |
| 1 TB over gigabit | 2.22 h | 10.8× | Just over two hours |
| 1 TB by posting a disk | 48 h | 0.5× | Two days, and utterly reliable |
| 1 TB over 40 Mbit/s upload | 55.6 h | 0.432× | |
| 1 TB over 10 Mbit/s upload | 222 h | 0.108× | About nine days |
Worth knowing
- Never underestimate the bandwidth of a parcel. A 20 TB drive posted overnight beats a gigabit line for anything over about 20 TB.
- Home connections are usually asymmetric: a 500/50 line uploads at a tenth of its download speed, which is what a backup actually uses.
Frequently asked
Why is my cloud backup so slow?
Because it uses your upload speed, which on most consumer connections is five to ten times slower than download. The first full backup is the painful one; incremental ones are small.
What is the 3-2-1 backup rule?
Three copies of the data, on two different media, with one off-site. Cloud backup satisfies the off-site part; it does not replace the local copy.