Last Updated 4 days ago
Filmmaking Dictionary: Number 1 / 1:1 Backup / Mirror
Definition
A 1:1 backup or mirror copy is intended to reproduce a source set of files without changing their contents. In a camera-media workflow, that usually means copying the original recording files and their folder structure to another storage destination.
The phrase describes the intended relationship between source and copy. It does not prove that the transfer succeeded, that the files are playable or that the production has enough independent copies to erase a camera card.
What Should Match?
A proper camera-original copy preserves the files the recording system created, including supporting metadata and folder structures needed by the camera software or editing application. Renaming individual files or copying only the visible movie clips can break a spanned recording or separate useful metadata from its picture.
- File contents: The copied data should match the source.
- Required folder structure: Preserve the camera’s original arrangement.
- Completeness: Account for every expected recording and supporting file.
- Traceability: Identify the card, destinations and verification result in the offload record.
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Copying Is Not the Same as Verification
A successful-looking progress bar is not a full data-integrity check. File names and sizes can match even when contents differ. Checksum verification compares calculated values for the source and destination data to detect transfer differences.
Verification also has limits. A matching copy can faithfully reproduce a source file that was already corrupt. Spot-checking playback, checking expected clip counts and reviewing recording reports address different questions from a byte-level comparison.
Mirror Versus Independent Backup
A live mirror may automatically reproduce changes from its source, including an accidental deletion. That can be useful for maintaining matching working storage, but it is different from retaining an independent recovery copy or earlier version.
For example, an assistant copies a camera card to two separately identified drives and verifies both copies. Later, an editor reorganises working media on one drive. An untouched second copy offers a recovery route that an automatically synchronised deletion might remove.
Common Mistakes
- Calling two folders on the same physical drive two independent backups.
- Reformatting a card before the production’s required copies and checks are complete.
- Treating RAID or a live mirror as protection against every form of data loss.
- Using ‘1:1’ to imply a forensic disk image when only a file-level copy was made.
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Frequently Asked Questions
Does 1:1 mean an image of the entire disk?
Not necessarily. A file-for-file copy and a block-level disk image are different operations. Specify which one the workflow requires.
Can I erase the card after one verified copy?
Follow the production’s media-release procedure. One correct copy does not protect against failure or loss of that single destination.
Related Terms
Browse all terms starting with 1 or return to the filmmaking dictionary.