The support forum

Different Hard Drive size after backup

Yobobvckup :

Jun 19, 2018

I have two 2tb external drives. One is the main drive and the second is the same sized drive and it is used only as a backup for the main drive.
I have just noticed that when i do a backup the source drive to the backup drive, the file size of the drives are different. I have noticed this one other time (different drive) since the last update but the drives were smaller so I just formatted and ran backup 2 again.
I use the default settings for the most part; delta copying, destination snapshot, delete backup copies of deleted items.
Has something changed in the last update?
Before the last update my backups were an exact mirror of the source drive. Now I'm worried that I'm missing or deleting files on my destination drive. I have tried to contact Bvckup support but no response in a week so I thought I'd ask here in the forums. Thanks for any advice.

Alex Pankratov :

Jun 19, 2018

Has something changed in the last update?

No, nothing of relevance.

What do you mean by "file size of the drive" exactly? Are you looking at the total byte count of all files as shown in "Size" line in Windows Explorer's Properties window or is it something else?

I have tried to contact Bvckup support but no response in a week

I see no traces of your email on our end. Can you resend it (to

Yobobvckup :

Jun 20, 2018

Mr. Pankratov;
Yes. I shall resend the email. I included pictures of the file size but I don't know how to do so on this forum.

And by file size, I mean total remaining space on the drive. For example, in my source drive I will have 200 gb of data on it, but on the destination drive I will only have 150 gb. I would think that since they are both the same size drives and I am "mirroring" the source drive, that everything should be identical.
When this happened before, I just formatted the destination drive and backed up my source drive and it came out the same.

I just thought I'd ask why this is happening before I am forced to do that again.

I thought of looking through the drive to see if any particular files are missing but it's almost 1.6 tb of data which I don't want to sort through.

Thanks for any advice.

Yobobvckup :

Jun 20, 2018

Mr. Pankratov;
I apologize. It seems I did get a response from you, but my email client marked it as spam. I just located it when I re-sent the email.

And thank you for the info. It's a bit technical for me but I'll look into it.  But just for the sake of  simplicity, you're saying that different file sizes are ok even if both drives are formatted the same and are supposed to be exact copies of each other; correct?


Alex Pankratov :

Jun 20, 2018

I will have 200 gb of data on it, but on the destination drive I will only have 150 gb.

The difference is then due to the presence of default rules that exclude various temporary files from backup. Since you are mirroring one drive onto another you can remove these rules - bring up Backup Settings window for the job, click on Details in Backup What section, click on any line in the bottom panel, press Ctrl-A and then use Delete to remove all rules. OK all the changes and re-run the job.

Another thing to keep in mind is the Backup Settings > Deleting option. It controls what happens to a backup copy of a file when the original gets deleted at source. By default the program will not delete the former right away, but stash it into a special folder called $Archive, keep it there for 2 weeks and delete only then.

Again, since you are mirroring one disk to another, you may want to change this setting to delete backup copies right away.

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