Synchronised disc operations

Are there any utilities that would group multiple discs, creating a group as a virtual block device whose interactions would apply to all members of the group? Sort of like a RAID mirror, not for redundancy, but for simultaneous writing to discs and then using each written disc in the group as an independent disc with written data. lvm and mdadm don’t allow to use their members after unmounting, they have some special partitioning on them.

All disc operations such as formatting and writing files would be applied to all discs at the same time, i.e. when the group was completed, each disc would have all that written data as it was written through the group to work with. For example, there are 5 discs in a group /dev/sdb-f. The group has some sort of custom identifier like /dev/mirror. Something like this.

Thank you for any information you can provide.