Backup Window Calculator

Work out whether a backup job finishes before the window closes.

What you provide

Use 100 for a full backup. Nightly incrementals are usually 1% to 10%.

Share of the rated speed a backup job actually gets. 70% is a fair working figure.

Result

PASS

Finishes in 1.8 h, inside the 8 h window

The job fits inside the window and leaves 6.2 h of headroom. Re-check the figure when the dataset grows by a quarter, since the run time grows with it in a straight line.

Backup window
012
1.8 hpass
  • Comfortable
  • Tight
  • Overruns

Window: 8 h

Diagnostic telemetry
Data movedFull copy of the dataset
500.0 GB
Effective throughput70% of the 1000 Mbps link
700 Mbps
Transfer time
1.6 h
Snapshot and verify
10 min
Total run time
1.8 h
Window used6.2 h spare
22%

What this cannot tell you

  • This is arithmetic on the figures you type in. It does not watch your backup job, read your storage or measure your link.
  • Real runs vary with file count as much as with size. A million small files can take several times longer than one large file of the same total size, because each one costs a separate metadata operation.

Take this with you

Backup Window Calculator on RunTheTests — free browser-based sysadmin tools, no sign-up.