How canI create a "Checksum" for an online folder?

I have a rather large folder in my cloud storage (OneDrive, Google Drive and Dropbox) It is 8GB large with 3-4 files. It is a backup of important folders from a computer that was long ago replaced and destroyed. I want to download this large folder and put it on a Thumb Drive then delete it from the cloud. Obviously clearing up some storage space.

So my concern is possible corruption in the process between cloud and Thumb Drive. Is there a way that I can create a Checksum for the cloud folder (or separate files in the folder) that can be used to check the integrity of the folder/files in the Thumb Drive before deleting them in the cloud?

I have searched but all I can find are ways to use an existing checksum to check the integrity of a downloaded file. Nothing on how to actually create that checksum on the file before downloading.

Why not copy down to a hard drive. The few extra dollars would be worth it and the hard drive is harder to destroy via stepping on it...etc.

Ideally the checksum should have been done before the upload.

Are you saying it's being stored on more than one cloud site? If so you can download it from two or even three of them and if the checksum is the same on each one then you know it hasn't been corrupted on this download and the odds of it being corrupted on three original separate uploads is pretty low.

I did find this for dropbox and google drive... may be helpful..

https://www.dropbox.com/developers/reference/content-hash



https://stackoverflow.com/questions/23462168/google-drive-md5-checksum-for-files


https://workspace.google.com/marketp...m/197544146915

This is a folder that I created 5+ years ago with Music,Photos,Documents from my sister's computer. I saved the "stuff" on my PC so that I could get it to her. In the years it has been uploaded to various cloud storage places. Several years ago I shared the folder and gave her a link to that folder for her to download whatever she wanted to save. She has long since moved out of state and as far as I know never downloaded the files. It is time for me to clear this up. At this point I could simply delete the folder and move on. But I have saved it for her this long I want to at least make a last attempt for her to get the data.

And in the process I'm trying to learn something. Might be useful to know how to create a checksum in the future for something truly important.

I'm not sure how you would create the checksums on the cloud side. Like fink said, the checksums would have had to be created before the upload.
Basically, you have to create a checksum for each file at the source, transfer the files, create checksums on the target drive, and then compare the checksums. Very tedious.
https://www.nextofwindows.com/5-ways...-in-windows-10

Do you have the same files saved at multiple cloud sites? It would probably be easier to just download the files from 2 different sites, and then do a binary compare with something like WinMerge.
https://winmerge.org/

I wouldn't save the files to a flash drive, because comparing the files would be much slower. I'd at least use an external USB hard drive, or better yet an SSD.

Also, I would not download the files to just ONE external storage device. You want at TWO copies of those files, preferably stored at different locations, in case one storage device is lost or destroyed.

How to verify copied files:

https://superuser.com/questions/7730...fy-copied-data

https://answers.microsoft.com/en-us/...7-93852d8e1bcb

SyncBack might also do what you want:

https://www.2brightsparks.com/resour...integrity.html

Thanks guys.

Looks like I was wrong about how to check the downloaded files with a checksum. That was the only way that I could think of. But jdc2000 has a much better way to do what I was wanting to do. I will certainly investigate the "verify copied files" links provided.

As of this particular instance I ended up simply downloading to my PC hardrive. Then moving to a thumb drive to send off to my sister. After the thumb drive was populated with the files I opened several of the photos and opened the music folder to see if they appeared to be ok. Crude way to confirm a download, but oh well. The photos opened and looked fine, with the exception being that a number of the photos were "blurry" as in not a sharp picture. Not sure if this is from the camera or the original upload. If I open the photos from the cloud site they have the same "blurry" image. So don't think that it has anything to do with this move of the files.

When all is said and done over this instance, I have learned something that will be helpful in the future.


Thanks again for the help. I love the VirtualDr you guys never let me down.

Cheers,
Ron