Sync again and Run again

Sync again and Run again repeat a transfer you've already set up, with the same source, destination and settings. The transfer compares both sides and sends only what is new or has changed, so topping up a large folder is quick when little has changed.

Where to find it

Select a transfer in the Data Transfers list. Once it has Completed, Failed or been Canceled, the button row at the top of its details shows:

• Sync again for a Sync (one-way) or a Bidirectional sync;
• Run again for a Copy or a Move.

The new run appears in the same row of the list as the earlier ones, with the run count going up by one.

What it sends

Each run looks at both sides and transfers only the differences: new files, and files whose size, date or content has changed. Files that already match are left alone. That makes Sync again the easy way to bring a big folder up to date, or to finish a transfer that failed or was cancelled part-way — files that had finished aren't sent a second time.

The operation still behaves as it always does. A Sync (one-way) run still deletes files at the destination that aren't in the source, and a Bidirectional sync run still carries deletions both ways. See Copy, Move, Sync or Two-way sync.

%% caption: What a repeat run does with each file
flowchart TD
  A[You click Sync again or Run again] --> B[Both sides are compared]
  B --> C{Is the file the same on both sides?}
  C -->|Yes| S[Skipped]
  C -->|No, new or changed| T[Transferred]
  B --> D{Sync one-way only: extra files at the destination?}
  D -->|Yes| X[Deleted from the destination]

Settings a repeat run doesn't carry over

• Dry run is switched off. Running a dry run again performs the transfer for real — handy once you've checked the preview, but worth knowing. See Trying a transfer first with Dry run.
• First run for this pair is never carried over for a Bidirectional sync. That box is for the very first run only; see Two-way sync and the First run box.

When it isn't offered

• While the transfer is still running, queued or paused. Use Pause, Resume or Cancel instead.
• For a Download. A large download already picks up where it left off when it's resumed.
• For a Move (Overwrite) started from Data Parking, because the source is gone once that kind of move finishes.

If the same transfer is already running, clicking the button again doesn't start a second copy of it.

Run again on a repeating transfer

A repeat of a scheduled transfer runs in the background at low priority, like its scheduled runs. It doesn't change the schedule — the next scheduled run still happens at its usual time. See Scheduling a transfer.

See also: Data Transfers · What happens to transfers when you restart · A transfer failed