Disk drives, also known as "hard drives" or "hard disks," have been the foundation of computers, but advances in technology mean that there are now several alternatives to hard disks for every computing need; flash memory offers a range of sizes and capacities that cover most people's needs. Hard disks still have some advantages over the alternatives, but the fast development of flash storage and other storage media is likely to make hard drives obsolete in the coming years.
For high-capacity storage, hard disk drives are the cheapest option per megabyte of storage space. The only alternative storage option if you need high-capacity internal or external storage is a solid-state drive, a form of flash memory. However, as of the date of publication, solid-state drives cost five to 10 times as much as a hard disk drive of the same capacity.
No other storage solutions offer commercially available capacities as high as hard disk drives. As of the date of publication, you can buy an internal hard drive up to 3TB in capacity for less than $200. External hard drives are commercially available up to a capacity of 6TB, although these can cost up to $500. Solid-state drives are rarely available at capacities over 512GB, and even at this capacity they cost between $750 and $1,000 at the time of publication. As of the date of publication, thumb drives and flash drives are generally no more expensive than $40 and can be as little as $10,
Hard drives typically come in two sizes -- a 3.5-inch drive often used in desktop computers and a 2.5-inch disk often used in laptops and portable external hard drives. While size is not an issue for internal hard drives, it reduces the portability and convenience of external hard drives. Small USB thumb drives, memory cards and optical discs are much more portable and occupy less space around a computer than hard drives, although they have lower maximum capacities.
Hard drives contain several moving parts inside an enclosure. These include spinning plates and a delicate arm. Having moving parts means the hard drive is prone to damage and read or write errors if it is moved too vigorously or too often without sufficient protection. Flash memory, including solid-state drives, does not have this problem as these drives do not contain moving parts. They are a more reliable choice, especially for laptops and mobile devices.
Hard drives have a slower average speed than any form of flash memory. A hard drive takes a short time to access the correct location of data on its plates, whereas a solid-state drive accesses data instantly. As of the date of publication, flash storage has read and write speeds approximately double those of hard disk drives, and a computer that uses a solid-state drive can boot up and access applications in half the time of a hard drive-based PC.