The single bay/single drive My Cloud models DO have a backup option. For the first gen v4.x its called Safepoint, for the newer gen v2.x its called Backup. This backup option will allow one to backup to a USB external hard drive that one attaches to the back of the My Cloud. It may also allow for backup to other local network locations. See the My Cloud User Manual (http://support.wdc.com/product.aspx?ID=904) or the My Cloud Dashboard Help for more information on how to use the backup feature of the My Cloud.
Further there are a number of unofficial hacks/scripts/modules one can use on their single bay/single drive My Cloud to backup the My Cloud unit. One can use the forum search feature, magnifying glass icon upper right to find the various other discussion topics on backup. Here are just three.
https://community.wd.com/t/app-goodsync-for-wd-my-cloud-backup-and-file-synchronization/173984
https://community.wd.com/t/happy-accident-includes-an-alternative-to-safepoint/96152
https://community.wd.com/t/guide-installing-crashplan-for-wd-my-cloud-cloud-backup/92425
