How can I do this?

[asce]

Once you save files in the first hard drive it will automatically backups in the second hard drive and when the first hard drive will damage the server is still working and my files is still i access using my second hard drive.

 

[Evertb1]

Once you save files in the primary storage it will automatically have backups in the secondary storage..

There must be a question in there somewhere I think. Do your self a favor and read the rules for the forum. And then reformulate your question ins such a way that people understand what you want to achieve. Primary and secondary storage are meaningless without context.

 

[Alecmascot]

Once you save files in the first hard drive it will automatically backups in the second hard drive and when the first hard drive will damage the server is still working and my files is still i access using my second hard drive.

If you set up a mirror with the two drives then each has same data and the mirrored volume will survive the failure of one drive and you can replace the failed drive and the mirror will be rebuilt automatically,

 

[Evertb1]

Once you save files in the first hard drive it will automatically backups in the second hard drive and when the first hard drive will damage the server is still working and my files is still i access using my second hard drive.

I see you edited and expanded your question a bit. Still, read the Forum rules. And if you are halfway serious about using FreeNAS, start reading up on some things. It will be of great benefit to you.
The ZFS primer: https://doc.freenas.org/11/zfsprimer.html
The Slideshow explaining vdev etc.: https://forums.freenas.org/index.ph...ning-vdev-zpool-zil-and-l2arc-for-noobs.7775/
The primer on terminology and abbreviations won't harm you: https://forums.freenas.org/index.php?threads/terminology-and-abbreviations-primer.28174/
And of course the complete FreeNAS Manual.

 

[danb35]

Easy way, but not exactly what you asked for: Set up a mirror with the two disks, as @Alecmascot said. All your data will be on both drives; if/when one fails it will be on the other (and you can replace the failed disk to restore redundancy).

Harder way, but closer to what you asked for: Set up two single-disk volumes, schedule periodic snapshots on the first, then use a replication task to copy the data to the second.

Your question, as best I can understand it, suggests you don't understand RAID very well--the resources @Evertb1 cited should help with that.

 

[wblock]

This can be done in different ways with ZFS mirrors, RAIDZ1/Z2/Z3, or replication from one FreeNAS system to another. Each has various advantages and disadvantages.

 

[asce]

Thank You..