Removable Storage Drives
Removable storage can refer either to a storage device that can be moved from computer to computer without having to open the case or to storage media that is removable from its drive.
Drive Enclosures
HDDs and SSDs can be provisioned as removable storage in an enclosure.
- enclosure provides:
- a data interface (USB, Thunderbolt, or eSATA)
- power connector (if necessary)
- protection for the disk
- can be connected directly to a network rather than to a PC
- referred to as network attached storage (NAS)
- Advanced enclosures can host multiple disk units configured as a RAID array
Flash Drives and Memory Cards
The flash memory underpinning SSDs can also be provisioned in the flash drive and memory card form factors.
A flash drive —also called a USB drive, thumb drive, or pen drive—is simply a flash memory board with a USB connector and protective cover.
- plugs into any spare USB port
The memory card form factor is used in consumer digital imaging products, such as digital still and video cameras, and to expand smartphone and tablet storage.
- PC can be fitted with a memory card reader device
- usually designed to fit in a front-facing drive bay
- reader then needs to be connected to a USB controller
- Most motherboards have at least one spare USB header for making internal connections
- Alternatively, the reader may come with an expansion card
- several proprietary types of memory card
- each has different sizes and performance ratings
- Most memory card readers work with multiple card types
- Secure Digital (SD) cards are available in three capacity variants
- SD has a 2 GB maximum capacity
- Secure Digital High Capacity (SDHC) is up to 32 GB
- SDXC is up to 2 TB
- four speed variants
- original specification is up to 25 MBps
- UHS allows up to 108 MBps
- UHS-II is rated at up to 156 MBps full-duplex or 312 MBps half-duplex
- UHS-III specifies two full-duplex rates of 312 MBps (FD312) and 624 MBps (FD624)
- Smaller form factor microSD, microSDHC, and microSDXC cards are also available