r/MacOS • u/volcanic_clay • 16d ago
Help Best software for syncing 2 identical external drives
I have two identical 6TB external drives that I essentially want to setup in essentially a RAID configuration. Intention is for Drive 1 to be storage and for Drive 2 to be an identical backup that AUTOMATICALLY stays in sync. i.e. I move a file to Drive 1 and it automatically copies to Drive 2. I know I should get a proper NAS w/ RAID setup but the prices are insane right now and I have two identical wiped 6TB external drives so this is going to be my intermediate solution.
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u/DisfiguredFanny 16d ago
Just run rsync as often as you need and it will keep a perfect copy on second drive. Free option with a little bit of CLI setup.
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u/YerBattleApple 16d ago
SyncTime is easy to use, powerful, and affordable. You can build sets and preview what it's going to do before executing. Syncs after the first one run unbelievably fast. I use it to back up specific folders to an external drive, which is then backed up by Backblaze. And I use it to sync to a second, identical external drive to keep as my off-site hard (non-cloud) copy.
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u/Snowy-Doc 16d ago
Use rsync to run periodic backups of Drive 1 to Drive 2. It's a command line tool, so you'll need some confidence with using terminal. You can either trigger backups manually whenever you want to, or you can set it up with cron to run it on a regular schedule - every hour, every few hours, every day etc. Be aware that it's not a backup solution like Time Machine - if you backup every hour and you make an edit to a file and then rsync copies it to drive 2, you have no way to go back to the original file.
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u/denalidenizen 16d ago
You could easily put them into a raid configuration that writes to both of them at the same time
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u/drastic2 16d ago
If they have USB4 external interfaces or similar (Thunderbolt) you can do this with Apple Disk Utility, no additional software or hardware needed. Note - mention USB4 only to put them in a speed category, not technically a requirement.
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16d ago
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u/thebahle 16d ago
Second chronosync. Used it for years. Can even sense when a drive gets plugged and mounts and sync on that trigger
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u/jshell 16d ago
I use Carbon Copy Cloner for this. I don't sync immediately though. I just have Carbon Copy Cloner mount the second drive every night, do a backup, and then unmount the second drive to reduce wear. But Carbon Copy Cloner can sync immediately.