As part of every job YoYotta reads back every file that has been written and compares it with the source file checksum.
Sometimes you need to start copying another camera card using the same card reader, so the full verification can be delayed.
Turn on Quick Verify when you need to copy another source to LTO tape and then verify the entire tape later on.
Additionally YoYotta can read the source twice to be absolutely certain that the copy is valid.

v2 v3

md5 /Volumes/DATA/S999_S001_T001.MOV

MD5 (/Volumes/DATA/S999_S001_T001.MOV) = ca5f38b8ddd7ce0be3320104227fd212

Checksums are verified automatically by YoYotta. However if you are interested you can calculate the MD5 in the Terminal on the Mac. Type md5 followed by the file path and name.

YoYotta calculates the MD5 checksums in parallel at high speed so this will not slow down processing.

MD5 Checksums

An MD5 checksum is a 32 digit hexadecimal number that represents the hash of the contents of a file. Changes to the contents of the file give a different checksum, so checking the MD5 is a great way to verify that a file is unchanged. The calculation of the MD5 is an industry standard so the integrity can be checked on any system. Even if performing a Quick Verify, YoYotta always calculates the MD5 checksum and stores it as an extended attribute for every file. This means that the file can be easily checked at any time in the future.
YoYotta v3 generates both MD5 and xxHash. xxHash is a newer checksum that is faster to generate, however as it's less common so YoYotta always generates both.

Source Verify

After copying, whilst verifying, the source is read again to make sure that it is consistent. This extra verify only happens once as the source is then marked as double checked. The source verify happens in parallel with the destination verify so it will only add time if the source is slow. In this case you can turn it off.
Use Source verify only if you think there is a problem with a camera card or hard drive.

Quick Verify

Keep Quick Verify turned off when archiving to perform a full verification.

Turn Quick Verify on when restoring files to skip the full verify.

Even with Quick Verify turned on YoYotta always calculates and saves MD5 checksums for each file, allowing a full verification to be performed later.

Copy complete

YoYotta has checked the files sizes and names after copying. The source card or drive can now be ejected.

Full Verification of archived files

Add or drop in a folder, drive or tape as a source.
If adding a tape, click the Refresh button above the Job table to mount and index the tape.

Manually verifying

In Manual Index settings Turn off Extract Metadata and Create Thumbnails and Select Quick Verify and click the Process button. This will perform full verification of all unverified files against the original checksum.
Once complete the files will be marked as verified.
If the files on the source media have already been verified then YoYotta will just check to see if they have been modified since the last verification, so the process will be quite quick.

Selecting Full Verify will force a full verification, so this will take longer as it will read all the files on the media.
Source processing is always available, even with an unlicensed copy of YoYotta.

If reports are needed set them up in the Edit Paths panel.

Verification works when the files were originally copied with YoYotta.
The media does not need to be in the database or have any CSV or MD5 files, this is because the checksum information is stored by YoYotta as hidden Extended Attributes on the drive or tape.
If the files were written by another application then YoYotta will create a new checksum for each file.
If there is an md5sums.txt file in the same folder then YoYotta will compare this checksum as well and warn if there is any mismatch.

Verify in progress

Verify complete

All the reports enabled in the Preferences panel will be generated.

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