Feature request: The ability to verify files AFTER a sync, not just before

[hsehestedt]

Let me explain two real-world scenarios where this would be helpful to me:

1) I ran into a situation recently where I had an SSD drive that was failing on me. This SSD was the target of data that I was syncing from another system using FreeFileSync. I had no idea that I was having any corruption until I one day decided to modify my FreeFileSync job to compare files not simply by checking the time and size, but by comparing file content. That turned out to be a really good move because I discovered a number of bad files on the target. I know that I could just manually run a compare using the option to compare file contents after the sync has been performed, but it would be nice if I could automate this. It turned out that every week or so I would get new files that could not be read on that SSD - and in every case these were files that were unchanged recently. It was the SSD going bad but a simple compare using the time and size would never pick that up.

2) Okay, this second scenario may sound a little crazy, I'm likely about the only person who does this, but stick with me on this...

I use Blu-Ray media to make archive copies of some important data. Because I on occasion need to update files written to a Blu-Ray disc before the data is fully finalized, I use the Packet Writing capability built right into Windows to write to my rewritable Blu-Ray media. This way a file(s) can be overwritten with a new version just as you would do on a hard disk. However, I'm not always too trusting of optical media, so after FreeFileSync does a sync to the disc, I always follow it up with another comparison check, this time comparing the actual file content. The problem is that it might take two hours for the first sync to take place, then I have to physically be there to kick of a comparison afterward. It would be nice if I could perform a sync, automatically followed by another comparison checking the file content. This way I could start a job before I go to bed, and when I get up in the morning it would be done - with a comparison already finished.

[Plerry]

In both above cases, there are the same two options.

• The potential file corruption took place during the sync (=while transferring or writing a file).
For this, FreeFileSync (FFS) has the option to Verify Copied Files. This would give you an instantaneous detection that something went wrong. Make sure to read the description and to follow the external link there.

• The potential file corruption took place after the sync.
No sync action or setting can protect you from this.
At best, you can use the the Compare by Content method when running the next sync and thus have a detection afterwards.

[hsehestedt]

Thanks for the response.

I had completely missed the Verify Copied Files option. That resolves my second scenario.

In my first case what I was hoping for was basically the ability to perform a Compare by Content (just as you noted) after the copy, but to do so automatically after the copy. That could save me hours of time, but I guess that it's not a highly sought idea.

Thanks for taking the time to respond.

[Plerry]

> I was hoping ... to perform a Compare by Content ... automatically after the copy.

But that is (within its mentioned limitations) exactly what Verify Copied Files (automatically) does: a binary comparison.
So, no need to hope; it is already there ...
Very likely (?) even using exactly the same algorithm as Compare by Content does. Why have two different algorithms for the same function?
An instant automatic renewed run of FFS, just comparing by Content, would suffer from the same limitations as mentioned for Verify Copied Files; data being read from some cache memory somewhere in the chain, instead of from disk.

But in any case, this is/would be only a detection of potential file corruption that took place during the sync, not if that took place after the sync.