There are many places on the high street to buy hard drives for data storage like PC World. You can also find hard drives for sale on both Amazon and eBay.
I believe that you mean to ask if hard disk drives are considered volatile storage media or not. Volatile memory is memory that is lost when the storage medium is not being supplied with electricity. Hard drives do not need power for storage, only for reading and writing data from and to the platters; this means that hard drives are not volatile storage media.
Primary storage, called RAM memory, is temporaty one that holds data and instructions while it is processing both. And slower but more permanent is secondary storage. And those are hard drives, CD drives, DVD drives, flash drives, Zip drives and floppy drives.
Hard drives are non-volatile, as you don't lose the data stored within if you turn off the power to them.
Hard disk drive inside the PC, CD or DVD drives/disks, USB (thumb drive, jump drive), and floppy disk drive/disk storage. Other storage can be external Hard disk drives, tape drives, RAID drives and the newer Blu-Ray.
There are many different options for data storage. You can use zip drive, external hard drives, or even online storage for your data needs.
Primary storage, called RAM memory, is temporaty one that holds data and instructions while it is processing both. And slower but more permanent is secondary storage. And those are hard drives, CD drives, DVD drives, flash drives, Zip drives and floppy drives.
CPU's or central processing units do not actually store data. There is a minimal amount of data on board but the storage takes place on the hard and solid state drives.
The purpose of secondary memory is storage of data that is not immediately needed for processing by the CPU. Examples of secondary devices are hard drives and optical drives.
Hold drives can hold the most data of any storage device. They can contain up to a few terabytes now and they are becoming bigger and bigger everyday.
SCSI is most commonly used for hard disks and tape drives, but it can also be used to connect a wide range of other devices, including scanners and DC drives.
The data stored on them is persistent (usually), that is they don't lose the data when powered off (unlike RAM).
Question is a bit vague, but you may be referring to hard disks. These are also known as secondary storage - permanent storage.