HDD or SSD? How to Buy Hard Disk Storage for 2019

Solid-state drives and hard disk drives come in all different shapes, colors, and sizes, so when it comes to selecting the right hard disk storage, business customers should understand the scope and purpose of the different types of hard drives that are available to them. Choosing whether to buy a HDD or SSD is the first and most important choice.

Both HDD and SSD fulfill the same function but differ in their mechanics and performance. We’ll cover the high-level pros and cons first.

SSDs have no moving parts, which makes them more reliable. They use semiconductor technology that writes and reads data by electrically charging a stationary strip of dense circuitry.  A solid-state drive is not an actual “disc” in the same sense as a HDD, which stores memory on spinning magnetic platters and read with an actuator arm.

SSDs have a performance advantage compared to spinning disks. End users do notice improved responsiveness on their PCs. Systems experience faster boot times and a have “snappier” feel when operating systems and production applications.

SSDs operate in silence. You can hear the motor inside a spinning disk drive as it reads and stores data. Light clicking sounds are normal. You cannot hear the electrical current performing the same task in a solid-state drive.

HDDs offer greater value per gigabyte of storage. Solid-state drives are generally five or six times more expensive per gigabyte of storage than their spinning counterparts. Seven or eight years ago, the high cost of SSD storage prohibited non-enterprise users from owning SSDs. SSD prices have decreased since then, but so have HDD storage.

HDD vs SSD: Comparing pricing for 1 TB disk storage

Samsung 860 EVO 1TB
MSRP $199.99

WD Blue HDD 1 TB
MSRP $69.99

WD 1TB External SSD
MSRP $499.99

HDD or SSD: What do industry trends say?

It’s not surprising that SSDs have started to replace HDD storage in many data storage roles. Better affordability amplifies the value proposition for SSD storage: better performance and reliability. Increasing popularity for desktop SSDs shows in market research from August 2018.

Businesses now gravitate more toward solid-state storage for use in end-user systems, like desktops and notebooks. With prices for 1TB – 4TB SSDs trending downward, it makes sense to upgrade data storage for PCs using flash memory. SSDs provide a way to extend the service life of a computer that might feel sluggish as it reaches end of life.

Hard drives aren’t going the way of the dinosaur. A strong business case remains for high-capacity, low cost per-GB hard disk drives. Manufacturers are selling fewer drives, but more storage capacity in recent years. Expansive hard drives—10TB HDDs and larger—are popular choices for data centers and backup copies of business data. These types of archival storage demands necessitate capacity over performance.

What is hybrid data storage?

Manufacturers make hybrid storage drives that house HDD and SSD storage in a single encasement. Why would you need this? A common storage configuration in workstation computers features both SSD and HDD storage. You would put the operating system and frequently used production applications on the SSD. A HDD stores files and lesser-used applications.

SKUs

Configuring a computer with a SSD + HDD tandem setup gives you the best of both worlds. Users benefit from snappy boot-up times and performance using the applications most frequently utilized. Companies might apply a similar setup at the server level. Hard drives are typically used in backup archives and shared storage servers. Performance-optimized application servers often use solid-state drives.

Seagate SSHD hybrid
1 TB HDD + 8 GB SSD

Is it better to expand system storage with external or internal hard drives?

Both HDDs and SSDs are designed to either fit inside a computer system, or as a portable standalone device. Portable drives have a hard plastic casing to protect against drops and debris. Inside their casings external and internal drives are the same.

The interface that internal and external hard drives use connect to a computer motherboard is a key differentiator.

All external hard drives (HDD or SSD) connect to a motherboard via USB. Almost all new external drives use a USB 3.0 interface. If you have an old computer with USB 2.0 inputs, USB 3.0 is backwards compatible and works—although data transfers at the slower USB 2.0 rate. Internal hard drives connect with one of several interfaces. Each of them is capable of a faster transference rate compared to USB 3.0. More details about bus and interface are below.

Desktop external hard drives contain one or two 3.5-inch HDDs in a hard plastic or metal enclosure. They have large capacities (4-8 TB) and are usually used for mobile backup and storage.

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Wireless attached storage drives can be accessed over a Wi-Fi by other computers on the network. The are interchangeably called ‘personal cloud’ storage because you can attach files from wireless devices on a WLAN. It is usually used for streaming media, and has capacity between 500 GB and 2 TB. It can be either a 3.5- or 2.5-inch encased drive. See all ‘personal cloud’ wireless attached storage drives.

Portable external hard drives have sleeker designs than their bulkier desktop counterparts, and are meant for easy transport. They can be either 2.5-inch HDD or SSD, and range in capacity from 32 GB to 6 TB. Portable hard drives with encryption and a ruggedized build, like this Data Locker Enterprise portable hard drive, are meant for use in the field.

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Internal hard drives: What is the difference between 3.5-inch and 2.5-inch?

3.5-inch drives are designed for desktop systems, servers, and rack enclosures. It is exclusive to HDD. These drives can have a higher capacity and are usually the most cost efficient storage options available.

2.5-inch drives (called “mobile” drives, though designed for internal use) are designed for laptop systems. They usually have smaller capacities and are slightly more expensive per-gigabyte, but offer better performance according to manufacturer specs.

How can you tell which are the fastest hard drives?

Data storage performance is measured differently in HDDs and SSDs. Several factors determine hard drive performance.

RPM ratings and HDD disk storage

For hard disk drives look at RPM ratings: the faster the platters spin, the faster the drive feels to the end user.

5,400 RPM is the standard drive speed for large-capacity archive hard drives designed for backup purposes and cold storage. Many are rated for 24/7 operation and designated for use in network attached storage: NAS hard drives

7,200 RPM is the standard drive speed for the main HDD on a modern PC designed for day-to-day production use, and in network attached storage (NAS) devices.

10K -15K RPM is the standard drive speed for enterprise storage arrays. These hard drives usually have SAS interfaces which are specialized for server motherboards. Hot swappable, meaning IT doesn’t have to power down a server to change out hard drives.  SAS enterprise drives typically are incompatible with PC motherboard interfaces.

Cache is a special section of memory aboard a hard drive that helps move blocks of data around the disk. The larger the capacity of cache, the better the HDD responds. Modern drives have 8-128 MB of cache memory.

Fast SSDs: Look at ratings for read/write speeds

SSDs are benchmarked for data transference by the number of megabytes per second it reads and writes data. Manufacturers quantify this metric—called sequential read and write speeds—and many post on the drive’s packaging or manual.

When people talk about a fast hard drive they are discussing transfer speeds, or bandwidth throughput. Transference is measured by the amount of data (gigabits, usually) moved per second (Gb/s). Internal hard drives will use one of several interfaces. Independent benchmarks seek to confirm these speeds. Understand that, as with any benchmarking, system variables come into play, as does the nature of the data being transferred.

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What are the different internal hard drive interfaces?

The mechanism that components use to communicate within a computer system is called a bus. An interface is a catch-all term for a connection point between hardware—or software—in a system. Hard drives interface with computer motherboards using one of several different bus types. Each bus type is standardized, and rated for theoretical transfer speeds.

SATA III is the current interface found on internal HDD and SSDs. SATA III controllers are designed for inexpensive performance and remain the standard interface for data storage in desktop and laptop computers.  If you have an older system with SATA II or SATA ports, SATA III is backwards compatible. Both HDD and SSD use SATA III.

SAS is an interface designated for large enterprise storage arrays and roughly twice as fast as SATA III. SAS drives are designed for multiple users accessing data simultaneously. The SAS interface allows drives to have built-in error protection features for added accuracy and reliability when reading and writing data. Both HDD and SSD use SAS.

What are M.2 and NVMe SSDs?

Non-volatile memory express, ‘NVMe’ for short, standardizes data storage hardware that slots into a motherboard’s PCI-Express interface. SSD technology is capable of reading and writing data faster than the SATA III interface can transfer it. NVMe drives slot directly into PCI-Express x2 or x4 slots in a computer motherboard and increases drive performance about seven times that of SATA III.

M.2 form factor SSD

NMVe PCI-e SSD

M.2 (pronounced M dot 2) denotes a form factor for a component that is meant to fit in a specific slot on a computer motherboard. If your computer was assembled within the last four or five years, it likely has a M.2 in the motherboard. M.2 parts are designed specifically for notebooks and laptops but desktop motherboards have M.2 slots also.

The M.2 motherboard slot is designed to accommodate several different types of high throughput/low power components like Wi-Fi adapters and Bluetooth connectors. When it comes to SSDs, depending on what type of pins you have, fits in PCI-e x2 or x4 slot, or work as alternatively-slotted SATA III drive.

What is more durable: HDD or SSD?

Both HDDs and SSDs wear out over time and eventually fail. Whether that happens in six months or six years, you never really know until the signs of hard drive failure are upon you. A company should always have critical data backed up and replacement drives in stock. Think of data storage hardware as a commodity.

With HDDs and SSDs, drive wear happens differently. HDDs and their spinning platters and mechanical arms can succumb to physical shock, or simply wear out over time. In recent years, cloud storage provider BackBlaze released data about which hard drive brands are the most reliable in their datacenter, but these methods were met with controversy in the storage community.

Even though SSDs have no movable (breakable) parts, they have a finite a lifetime because the NAND degrades after a certain number of program/erase (P/E) cycles. SSDs are typically rated for 4,000-5,000 P/E cycles, but this is just an average estimate.  In general, SSD technology is very reliable and drives will most likely reach obsolescence before failure.

Special types of Hard Drives

Enterprise Drives – Enterprise HDDs and enterprise SSDs are built for datacenter use. Manufacturers design these types of drives for 24/7/365 use in servers or workstations.

Helium HDDs – Helium hard drives have the spinning data platters housed in a helium-filled chamber. The idea is that since helium is lighter than air, the mechanical parts experience less friction, thus reducing wear and tear on the drive.

NAS HDDs – Even though virtually all HDDs work with network attached storage, some drives like the WD Red series are optimized for NAS systems. Like enterprise drives, they are tested for 24/7 operability, have vibration-resistant features, and have firmware that helps with compatibility and integration.

Surveillance HDDs  – Seagate SkyHawk and WD Purple HDDs firmware to support multiple video surveillance cameras as part of a multi-bay surveillance solution. They are tested for 24/7 operation and are a standard 3.5-inch / SATA III form factor and interface.