I've read through the backup thread, but didn't exactly see what I'm looking for.

 

Is there a free solution to easily backup my user shares? Now that all my data is spread out over drives, I can't  use SyncBack anymore to keep backups in sync unless I have 6 additional drives. I have 6 drives in my unRAID now, and I have 10TB of other drives around, but I'm not sure how to best keep them synced since those 10TB are on 4 drives vs the 15TB on 6 drives. I'm only using 7TB of data out of the 15TB available, but data is spread across all the disks.

 

Any recommendations for the best solution?

There are several ways to do it.  One is to always write to your "current backup" anything you're writing to the array.    Then your set of backup disks will always contain a complete set of your data.  But this, of course, doesn't provide the simple synchronization you can do with SyncBack, SyncToy, etc.

 

A better approach is to put all your backup drives in a spare system, and map them as a single drive -- mirroring the shares you have on UnRAID.    This system can be another UnRAID server; or a Windows box with the drives configured as dynamic, so the complete set of drives can be one logical drive.    Then you can simply use SyncBack to do your backups just as you're done in the past.    If you use a Windows system for this, you can even run Syncback on the backup system, so you don't need an intermediate system to do the actual backups.

 

Use rsyncd running on a second server. I mirror entire disks. If I do loose a drive, I can drop in the backup and recalculate parity.

Mirroring the individual disks does allow a simple disk swap and New Config ... but also requires that the backup disks are all the same size (or larger) than the disk(s) they're backing up.

 

I prefer techniques that don't have that requirement -- that lets you repurpose old (smaller) drives for backup use as you upgrade the drives in the primary array.