Before you start.
Verification is what turns a copy into a backup. A cryptographic hash — a deterministic fingerprint of the file's contents — gets computed from the source bytes and again from every destination's bytes. If the fingerprints match, the file matches. BLAKE3 is the modern choice because it's as strong as SHA-2 and several times faster, so verification doesn't become the bottleneck.
- SyncShot installed
- Latest build on the Mac doing the copy. BLAKE3 verification is built in — nothing extra to install.
- A job worth verifying
- Any job where the source is finite — a card, a phone, a folder. SyncShot can verify ongoing syncs too, but the canonical case is a single offload.
- Destinations that respond honestly
- Most do. A few network destinations cache aggressively; SyncShot reads the bytes back to compute the hash, not the cache. Make sure write-through is honoured where it matters.
- Patience to wait for green
- Verification is the part of the job that says the copy actually worked. Don't eject, don't unmount, don't move on until the report is green.
Step by step.
- 01
Make sure verification is on for the job
In SyncShot, verification is the default — but worth a glance before a job that matters. Confirm hash verification is enabled for the destinations you care about. If it's on, every byte written is checked against the byte that came off the source.
- 02
Start the copy
Run the job as normal. SyncShot computes a BLAKE3 hash of each file as it's read from the source. The same hash function runs over what every destination wrote, and the two are compared.
- 03
Watch the verification column
Each file gets a verification result per destination — a green mark when the hashes match. If a destination wrote something different from what was read, the row goes red and SyncShot retries the write before moving on.
- 04
Wait for the job to finish
Verification finishes when the slowest destination finishes. Don't eject early — a copy that hasn't been verified is just a copy.
- 05
Open the job report
Every file, every destination, every BLAKE3 result, all on one page. The report is the document of record — save it with the shoot if you keep paper trails.
- 06
Check the failure list
If anything didn't verify after retry, it lands in the failure list at the top of the report. That list is short by design; the common case is empty.
- 07
Re-run if anything failed
If a destination has a genuine write failure — a cable dropped, a drive dismounted — run the job again to that destination only. SyncShot picks up where it left off and reverifies the new writes.
After it's done.
A verified job is a document. The report can be saved alongside the shoot — a record that on this date, these files, these hashes, landed in these places. That record is what archivists and insurers ask for; it's what makes the difference between "we backed it up" and "we can prove it."
- Save the report with the shoot
- Export the report and keep it in the shoot folder. Three years from now, a question about what landed where is answered in seconds.
- Re-verify older copies on a schedule
- Bit rot is real, especially on spinning disks and aging SSDs. SyncShot can re-hash an existing copy and check it against the original — schedule it for the archive once a year.
- Trust the green, investigate the red
- Green means matched. Red means investigate — usually a cable, a drive, or a network share, never the bytes. SyncShot tells you which file, which destination, which result.
Verifying a fresh card? Camera to Mac. Verifying a phone? iPhone to a drive. Or browse every destination SyncShot can verify against — the full list. More step-by-step at the user guide hub.