Is it possible to verify a backup?
I am using Windows 7 "Backup and Restore" to backup data to a Blu-ray disc. Is it possible to verify the backup integrity after the job is complete? My concerns include scenarios where the media becomes corrupted or the backup does not complete without confirmation. Ideally the data written to the media would include an index file with checksums for all of the file content and there would be an operation to read back all of the content and compare the checksums. I can't find such an operation in the user interface.
February 18th, 2011 10:20pm

There is no verify option in Windows 7 Backup and Restore, but you can use a second hard drive to test the image by restoring it (if you have one). Some third party imaging software has a validation check. Have Questions About Installing Windows 7? FAQ - Common Windows 7 Installation Questions & Answers
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February 20th, 2011 3:16am

Here is what I would do. Download a copy of ExactFile . This will allow you to create a digest of all files within a single root partition or directory. After the checksums have been computed, backup your data to the Blu-ray (possibly with the outputed checksum file). Use ExactFile to verify the data AFTER you restore the backup. Alternatively, you can create a digest of the backup itself if you feel confident of the integrity.
February 20th, 2011 11:10am

Thanks for the replies TrekDozer and Chris-Jones. I suspected that Windows 7 Backup and Restore did not have a verify option but it is nice to have confirmation of that. I have not used ExactFile before however the technique you describe is generally a rigorous way to verify file integrity. I have traditionally used SHA256sum to create hash files and ExactFile looks it has a nice Windows user interface for hashes. Since Windows 7 Backup and Restore uses its own internal file format for storage on the backup media it does appear to be necessary to perform a full restore in order to get at copies of the files that can be used for the external hash comparisons. Unfortunately, the technique of separately creating my own hash file, performing a full restore, and then comparing against the original hash is a worst-case scenario. The addition of a backup verification operation in Windows 7 Backup and Restore would be a useful enhancement. I will have to find a place to submit an enhancement request. It would also be helpful to have some technical documentation from Microsoft to clarify if Windows 7 Backup and Restore at least has the capability to detect corruption when it is performing the restore. If it has internal hashes that it checks during the restore process I could trust in those and the execution of a full restore without error would be sufficient to confirm verification without the need for externally created hashes.
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February 20th, 2011 12:50pm

· Hi User1, You can use W7 Disk Management to Attach the backup as a virtual harddisk, please try the following. In search bar type Disk management hit enter - click on the Action tab at top of window - Attach VHD - use browse to go to the disc where your backup is, keep opening each folder until you get to .vhd file There should be 2 files, choose the larges. Click on it and choose the open tab. Then click ok. W7 should now mount the virtual harddisk it will be highlighted in a blue colour. If it has you will now be able to right click the partition and explore it like a normal harddisk to check your data files.Please bear in mind, that my answer is based on the details given in your post. The more I get the better the answer, Slan go foill, Paul
February 20th, 2011 1:15pm

Thanks for the reply artiste1. Mounting the backup files directly would certainly make an external hash file more useful since a full restore process and all of the storage space that entails could be skipped.
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February 20th, 2011 4:53pm

A post by "Sneha [MSFT]" in the thread [http://social.technet.microsoft.com/Forums/en-US/w7itprogeneral/thread/bbd398bd-aab4-4719-bc2a-9aa05c0057f3] reports that "Windows backup creates .zip files to store file backups and a VHD format to store image backups." The technique of mounting the .vhd files would therefore only be relevant to image backups.
February 21st, 2011 9:30am

Hi User 01, The Backup zip files are user Appdata files. The .vhd files are a complete image of the harddisk and are in my opinion more useful.Please bear in mind, that my answer is based on the details given in your post. The more I get the better the answer, Slan go foill, Paul
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February 21st, 2011 10:36am

I will have to look into the system image backups and consider purchasing an external hard drive to write them. When I select a Blu-ray burner as the backup location the "Set up backup" dialog reports, "The selected backup location does not support the creation of system images."
February 21st, 2011 11:38am

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