YoYottaID can read the source twice to be absolutely certain that the copy is valid.
YoYottaID reads back every file that has been written and compares it with the MD5 checksum from the source.
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.

md5 /Volumes/DATA/S999_S001_T001.MOV 

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

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

YoYottaID calculates the MD5 checksums at very high speed so they will not slow down 

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 YoYottaID always calculates the MD5 checksum and stores it as an extended atrribute for every file. This means that the file can be easily checked at any time in the future.

Source Verify

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 if you think there is a problem with a camera card or hard drive.

Quick Verify

To disable the full MD5 verification turn on Quick Verify in the Preferences panel. Don't turn this off if you are making archive tapes, as you will probably be deleting the original files. So you will want to be certain that the archive has been verified. However if you are restoring files then you can turn this off to save time.
The MD5 will still be calculated and saved for each file, allowing the verification to be performed later.

Copy complete

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

Full Verification of the backup files

Drop the backup folder in as a source.
The original source files are not needed.

Quick or Full Verify?

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 MD5 checksum.
Once complete the files will be marked as verified.
If the files on the source media have already been verified then YoYottaID 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 YoYottaID.

Verification works when the files were originally copied with YoYottaID. If the backup was made with another system then YoYottaID will create a new checksum for each file.
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 YoYottaID as hidden Extended Attributes on the drive or tape.

Verify in progress

Verify complete

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

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