Mirror Sync to preloaded mirror copy

Relayer

Setting up a new mirror sync from a NAS folder (with 31k files in 685 sub-folders) to a local folder which already has a copy of all the source folder's contents. The idea is to avoid the initial copying off all the source content to the target, which takes about 10 hours. Instead, it appears that the mirror sync is still taking 10 hours and perhaps overwriting all the destination files. Is this correct? if so, what needs to be done to use a preloaded destination copy and avoid the prolonged initial mirror copy?

Relayer

BTW, this is per AOMEI Backupper Pro v7.3.0

admin

@Relayer, When you sync the NAS folder to a local folder, it will create the NAS folder under the destination folder you selected. If there is a folder with the same name as NAS folder under the destination folder, it will sync data to the same name folder and re-sync all files and delete different files from the folder.

Relayer

Thanks for the response.! Some elaboration then:

1. Is there a way to avoid the re-sync of all files? For me, that initial mirror sync takes about 10 hours while making the host running the sync unusable due to high CPU, memory and disk utilization during the sync. I have four (4) such mirror sync's that I wanted to establish. I am looking at 40 hours then to get them all up and working. Not practical...!
2. Specifically, how does the mirror sync detect that the files I pre-copied to the destination were 'not' placed there by a prior execution of the mirror sync? I assume mirror sync does NOT re-sync all files every time it is executed but instead has a way to detect what changes need to be applied to the destination (i.e. what files are new or changed or removed from the source). 
3. Does mirror sync do some sort of comparison at start of process -- comparing source to destination?  Or, does it store some sort of catalog/registry for itself? 
4. Lastly, is there some documentation that I can access on how the mirror sync process works? I found nothing in the Help Documents beyond the basics.
   
   Thanks in advance for any insight anyone can provide.

admin

@Relayer, The Mirror Sync will sync all data for the first time. But, if the destination has same files (same name, size, and date), it will skip and don't sync the same files. So, for the files you pre-copied to the destination, please confirm if they have the same name, size and date as the source files.

If these files have the same name and size, but different dates, sync will sync source files to overwrite them.

When you run the mirror sync for the second time, it will only sync changed/added files of the source and delete different files from the destination.

In addition, please note that Mirror Sync will sync the whole source folder to the target path you selected. If you want to only sync files/folders under the source folder to the destination that you pre-copied files to, you need to select the parent directory of the destination as target path of the task and confirm that the destination folder name is the same as the source folder.

Relayer

Thanks again.! I thought that my destination folder's files and folders matched the whole source folder but I wanted (per your specifics) to make sure since I had copied using Windows Explorer (copy and paste). So I deleted it and then recreated it using robocopy which by default will make sure that all files are copied with (data, attributes, and time stamps) the same AND all folders are created the same (data and attributes).

Then I compared the destination folder contents to the source folder contents using WinMerge which compares not only dates and size but also the file's contents. Everything is identical. 

I then started my mirror sync. I can't tell exactly what it is doing but its been running for four hours and shows only about 1/3 complete. Now its run for almost 6 hours and is 38% through the files (31780 files, 12071 complete).

Based on the last response above, I would have expected all files to have been skipped. I don't think that is what is happening. I can compare the two folder tree's (using WinMerge) based on dates & size in about 20 minutes. Obviously, the mirror sync is doing much more and NOT skipping the matching files... 

Is there some increased logging for mirror sync that I can enable? It might help to see exactly what mirror sync is doing in my scenario. I have reviewed all current logs in "C:\Program Files (x86)\AOMEI\AOMEI Backupper\7.3.0\log" but none provide any details for the mirror sync in progress. 

I have decided to let the sync run to it's conclusion but I have four (4) more folders with a similar number of files where I want to start a mirror sync for each. I don't want to wait 10 hours for each on first sync of each one. I need to understand what might have undermined my preload.

I am also concerned that my second sync of the current one may not sync only the changes but repeat all files. I will know tomorrow when I start it again a second time...

Thanks in advance.!