Windows Home server v1.

This has served me ( ha ha ) for nigh on 15 years doing exactly what was said on the box.
PC backups, which you could then backup to external USB drives. Able to recover from where your last backup was done, OS and all.
Media and document storage, across multiple disks (JBOD), with folder duplication across separate discs.
Again, able to backup to external USB drives. Did some neat trick with only backing up the file changes, but was able to copy files in their entirety from the last backed up directory.
Easily recovery from a failed disk. Just remove from the pool, put new disk in, add to pool.

Recently retired WHS, as it was overworked. Some processes were hogging HDD activities to do with balancing, but not too good on nearly full drives.
Wouldn't support any thing greater than 2TB hdd, and only supported 512 byte sector allocation.
Yeah, and insecure. No access to internet

Retained most of the hardware, except an ailing disk, added extra RAM.
Replaced with W10 and DrivePool, and some FreeFileSync macros.
So far looking like a good replacement