Hello all,
I am new to this forum and the software. Before I download the program and start learning how to use it, I have one concern:
I would be mirroring two large external drives to one another (two 5-bay level-5 RAID arrays). We are talking about 20TB of data. One of the two drives will be completely empty when I start the mirroring. I am not worried about the time the initial backup will take -- likely days, not hours. I am worried about how long it will take to perform subsequent backups. I would like to update the mirror every month or so so all new files and all old files that have changed need to be copied. The software would have to determine which files are new and which files have changed before copying. I am afraid this, again, might take days.
Does anyone here have experience with the backup of large amounts of data?
Thanks in advance!
Cheers,
Peter
Large amount of data
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- Joined: 24 Nov 2025
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I have not yet hit 20TB, but I have 9TB on my NAS. It is a ZFS1 with five HDDs, and it is backing up to a single 16TB BitLockered HDD using a USB 3.0 dock and over my 10gb network. This 9TB is a mix of large files, like videos and PC images, and tons of tiny files, like Android Studio projects and pictures. 21k directories, 96k files.
It took ~40 seconds to complete the comparison between the two locations. Assuming linear scaling, you're looking at 90 seconds to compare. Slower connections will lengthen this, of course. If they are directly connected to the computer using USB 3.0, you should see around that amount of time to compare. Hopefully they offer something faster, like USB 10gb or higher, and it might be faster. I would expect it to be well within reason to back up even more than monthly without much hindrance.
The only concern I will mention is the RAM limitation. About 1 million file pairs per 1GB of RAM. Likely never to be an issue, but I don't know your data scope lol
https://freefilesync.org/faq.php#limitations
It took ~40 seconds to complete the comparison between the two locations. Assuming linear scaling, you're looking at 90 seconds to compare. Slower connections will lengthen this, of course. If they are directly connected to the computer using USB 3.0, you should see around that amount of time to compare. Hopefully they offer something faster, like USB 10gb or higher, and it might be faster. I would expect it to be well within reason to back up even more than monthly without much hindrance.
The only concern I will mention is the RAM limitation. About 1 million file pairs per 1GB of RAM. Likely never to be an issue, but I don't know your data scope lol
https://freefilesync.org/faq.php#limitations
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- Joined: 24 Nov 2025
Thanks, Xenon! That is encouraging. Anything under 10 minutes is golden. I will give this a shot! Thanks again!
We are talking several million files, though. Like 20 or 30 million.
We are talking several million files, though. Like 20 or 30 million.
