Back up update taking ages

[mark_ferrari]

HI, I just started using FreeFileSync yesterday but I have the impression I might be doing something wrong. I basically want to use it to back up a few big folders on my desktop mac to different external hardrives and update the backups regularly. I've been using Synkron for this in the past but it eventually stopped working.

So yesterday I created a session to back up one of this folders in Mirror mode and proceeded. Everything went smoothly and the folder was basically copied onto the external hardrive.

Today I tried to run an updated of that back up, which I thought it would simply mean to run the sync again but to my surprise, even though only a few files have been added /changed in the source folder since yesterday, the "comparing content" phase is taking forever. The folder is pretty huge but if each time the two have to be compared entirely at this rate it doesn't seem as a viable option for maintaining back ups.

Am I doing something wrong here?

Thanks

[therube]

each time the two have to be compared entirely

That is going to be the case regardless.
With a Time/Size compare, that's relatively quick.
With a Content compare, it will be relatively (to Time/Size), long.

If comparing Content, it cannot know if the Content changed without checking.
If comparing Time/Size, it cannot know if Time/Size changed without "looking".

While you may have just backed up, you can assume your backup is correct, but you cannot know.
If you check content of your source & compare that against your backup & if they compare, then you know the two are the same.
But that does not mean that an hour from know, for whatever reason (like disk problem) your prior successful - compared backup had not corrupted itself.
So when FFS goes to compare, again, it has to actually go out & compare to verify that the file is unchanged.

The same holds true regardless of how you go about it, only depending on method used, the time taken can be significantly different. (There will always be a trade-off between time & "validity".)

There are other ways to go about things.
You could use FFS to effect the copy & then use another means to check validity.
So copies could continue as you need them.
And validity, from time to time, as you feel is needed, in that trade-off between time & validity.

[mark_ferrari]

Hi, thanks for the explanation. I get the difference, I honestly never thought of it that way. Probably any other software I used before (Syncron, Sync Folders Pro) only compared Time/Size then?

Anyways, if it takes this long each time is not viable as a backup option. I just need it to keep that copy updated constantly. Any advice on how to get Sync Folder Pro to do that? Maybe I should use RealTime Sync?

[mark_ferrari]

ok I've found that you can just set it to compare Time/Size instead, I guess that's what I needed.