Removable hard disk drives (RHDD) are a form of removable media which includes magnetic tape that address many common use cases. Usage scenarios include enabling bulk data portability for larger environments or for D2D backup where the media needs to be physically moved offsite for small and mid sized environments. RHDDs include among others those from Imation such as the Odyssey (which is what I use) and the Prostor RDX (OEMed by Imation and others). RHDD, tape along with other forms of portable media including those that use flash by being removable and portable presumable should have some extra packaging protection to safeguard against static shock in addition to supporting encryption capabilities.

Compared to disks including RHDD, tape for most and particularly larger environments should have an overall lower media cost for parking, preserving and when needed serving inactive or archived data (e.g. the changing roll of tape from day to back up to archive). Of course your real costs will vary by use in addition to how combined with data footprint reduction and other technologies.

A big benefit of RHDDs is that they are random meaning data can be searched and found quickly vs. tape media which has great sequential or streaming capabilities if you have a system that can support that ability. The other benefit of RHDD is that depending on their implementation, they should plug and play with your systems appearing as disk without any extra drivers or configuration or software tools making for ease of use. Being removable they can be used for portability such as sending data to a cloud or MSP as part of an initial bulk copy, or sending data offset or taking home as part of an offsite backup, data protection or BC/DR strategy as well as being used for archiving. The warning with RHDD is their cost per TByte will generally be higher than compared to tape as well as having to have a docking station or specific drive interface depending on specific product and configuration.

RHDD are a great compliment to traditional fixed or non removable disk, Hybrid Hard Disk Drive (HHDD) and Solid State Device (SSD) based storage as well as coexist with cloud or MSP backup and archive solutions. The smaller the environment the more affordable using RHDD become vs. tape for backup and archive operations or when portability is required. Even if using a cloud or managed service provider (MSP) backup provider, network bandwidth costs, availability or performance may limit the amount of data that can be moved in a cost effective way. For example placing an archive and gold or master copy of your static data on a RHDD that may be kept on site in a safe off-site place and then sending data that is routinely changed to the cloud or MSP provider (think full local and offsite plus partial full and incremental in the cloud).

By leveraging archiving and data footprint reduction (DFR) techniques including dedupe and compression, you can stretch your budget by sending less data to cloud or MSP services while using removable media for data protection. You would be surprised how many TBytes of data can be kept in a safe deposit box. For my own business, I have used RHDDs for several years to keep gold master copies as well as archives offsite as part of a disk to disk (D2D) or D2D2RHDD strategy. The data protection strategy is also complimented by sending active data to a cloud backup MSP (encrypted of course). It might be belt and suspenders, however it is also eating my own dog food practicing what I talk about and the approach has proven itself a few times.

Here are some related links to more material:
Removable disk drives vs. tape storage for small businesses
The pros and cons of removable disk storage for small businesses
Removable storage media appealing to SMBs, but with caveats
StorageIO Momentus Hybrid Hard Disk Drive (HHDD) Moments