Understanding the data differences between Sync and Copy

[costwisewpg]

Hello All,

I'd like to better understand the data consumption differences between Sync and Copy.

Assuming I have 100 Gb of data that has already been copied to another server, be it Amazon, OneDrive, or another Freenas box. Where the second location is just the backup. It seems that Sync would be the best option as I would like the offsite backup to essentially be a mirror of the onsite server.

First question. Does that make sense? I'm a home user, I could probably take advantage of snapshots or something more but, I'm currently content with my onsite server and my offsite backup. Much better than most non-IT folks like me I'm sure.

When the sync task runs, it takes for-absolutely-ever. Keeping in mind, I guessed the first sync would take for ever, and it did. However, the subsequent sync's seem to be taking just as long. This gets to the heart of my question. When syncing, is the system just checking the file name and a Last Modified date or is it re-uploading the files?

If it's uploading the files, is there a better way to sync two systems? Something that just checks the file names and last modified dates and only uploads the data if there is a difference?

Thanks in advance!

 

[JohnDigital]

When syncing it should only be copying over new or changed files. Are you using rsync or how exactly are you doing this sync? I think what you are doing makes sense. How fast is your upstream internet connection? This will be your speed limiting factor. If you are trying to mirror any sort of media files, it could take forever.

Id run something along the lines of rsync -avvhz --progress /path/to/local/directory/files USER@123.123.123.123:/path/to/remote/directory/files from the FreeNAS host terminal. This will basically mirror in every way the two directories, looking in the local directory comparing it to the remote directory and copying new or changed files over. Unchanged files wont be copied. Im also assuming you have SSH/shell access to this remote server.

You might try to do a --dry-run first and see what it is going to do. You can also do a dry run with the -n flag. Make sure your paths are correct, and if you dont have alot of changing data it shouldnt take very long (the exception could be media files).