# Monitored backup with checksum



## kqr (Sep 8, 2017)

I recently discovered SnapRaid, which is essentially a backup tool that mirrors your drives onto another drive, it checksums local files and restores them if they get corrupted inadvertently. Except instead of storing full backups, it stores parity stripes.

Of course, basing it on parity instead of full copies trades some resilience for extra storage space. However, I think I prefer full copies.

Is there anything like this for FreeBSD?

Edit: so somewhat like zfs, sure, except more flexible in terms of upgrades and such.

Second edit: in other words, I value integrity over space and availability. A key feature would be automatic corruption detection, which is why just plain old rsync isn't enough.


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## chip64c (Sep 8, 2017)

I tried something like the following:


```
mount -vvvv -o ro -t msdosfs /dev/ada1s1 /media ; \
cp -rf /media/._dc7600.particle_ /usr/home/dc7600 ; \
umount -vvvv /media ; \
chown -v -h -R dc7600:dc7600 /usr/home/dc7600/._dc7600.particle_
```

Turns out, it works; I have 2 hard drives (one 80GB, the other 500GB); when I needed to transfer stuff for backup, I back it up to the 80GB FreeBSD drive.   Transferred it back to the msdosfs partition so I could put Linux on the 500GB hard drive; worked for me today!   I mean, you could always build in a command such as `openssl hash -md5` and run that over your files just to check, then run something like `diff` or `pdiff` to check for differences so you can verify file integrity?


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