Used with cache yes pool in Unraid and all worked well.
That mean first backups goes to cache disk and when mover run it move from cache to Array Disks of Unraid.
For snapshot and files backup from Windows machines.
But some time ago founded that the last files backups not fully moved from cache some dirs anf files not moved. maybe becose symbolic links.
Snapshot are OK.
Is There is Good idea to Use Cache for Files Backups?