PC configurator - Internal HDDs

Internal hard drives are installed in desktops, laptops, tablets, and mini PCs. However, they are also increasingly used in smart data storage (NAS) solutions and, of course, in servers.

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Internal Drive Types

If you have enough space for two separate disks, the ideal choice would be to combine an SSD and HDD. You install the operating system, programs and games on the SSD, and the HDD serves as the storage space for movies, music, and photos. If you have space for only one disk, you can leave the storage function to an external disk or NAS, or get one larger SSHD that you can split into 2 partitions (two logical drives).

SSDs - have very high data transfer rates. You can use them to build a powerful desktop computer or upgrade an older PC (replacing the HDD with an SSD will significantly speed up the system). Even as an external drive, these disks can make copying data from/to a PC up to 10 times faster. In addition, they have excellent shock resistance.
HDDs - have the best price/storage ratio. However, they are relatively slow (though the 7200 rpm drives are faster) and noisy. This type is more suitable as a storage solution for movies, music, and photos.
SSHDs - they work like classic HDDs, but they also have a small SSD part that helps to quickly access data and the operating system. They represent a solid compromise between SSD and HDD.

How big should my internal drive be?

What capacity should my system drive have?

The absolute minimum for a system drive is 120GB. This capacity is enough if you want to install and run the operating system and most programs (applications) without trouble.

240GB and more - operating system, all programs, and a couple of games.
480GB and more - operating system, all programs, and about 10 games.
960GB and more - operating system, all programs, a large number of games, plus some videos and photos.

Indicative Comparison of Disk Capacity and Usage

Capacity	Video (DVD)	Music (MP3)	Photos (JPG)
120GB	25 movies	24,000 tracks	30,000 shots
500GB	106 movies	100,000 tracks	128,000 shots
2000GB	425 movies	400,000 tracks	512,000 shots

Internal Drive Types

PC drives (3.5"/2.5"/special) - compatible with any desktop, you can use them wherever reliability is not a critical factor.
Laptop drives (2.5"/special) - drives for laptops and mini PCs, you can also use them wherever reliability is not a critical factor.
Storage drives (3.5"/2.5") - for NAS, set-top boxes, multimedia centers, camera systems, and other 24x7 uses (non-stop operation).
Server drives (3.5"/2.5"/special) - dedicated server disks, usually allow hot-plug/hot-swap connection.

Internal Drive Speed

Sequential read/write speed (MB/s) - continuous transfer of large files, typically movies and other videos.
Random read/write speed (IOPS) - transfer of randomly placed files; these values determine how fast the operating system and installed applications will boot and run.

Classic HDDs (hard drives) generally deliver 120-150 IOPS, SSDs reach up to 100,000 IOPS. Needless to say, the SSD format is a better solution for running the operating system and program applications.

Most Popular Internal Drive Interface Types

The drive interface determines the maximum theoretical bandwidth throughput. The most commonly used internal drive interface is SATA; with SATA II you get up 300 MB/s, while SATA III offers up to 600 MB/s. Both versions are usually compatible with each other. The most common compatibility problem arises when someone wants to install a modern SSD on an old computer with SATA I interface (150 MB/s). In this case, installing a SSD doesn’t even make much sense and it’s better to just buy a new PC. Generally speaking, make sure to choose the interface your motherboard supports (that’s where you are going to mount the drive).

SATA - SATA III offers twice the speed of the previous SATA II.
M.2 - determines the interface as well as the disk format. M.2 interface with NVM Express (NVMe) controller provides a throughput of nearly 4GB/s.
SAS - used with server disks.

Interface	SATA II	SATA III	SAS	M.2, U.2 (PCIe, NVMe)
Max. throughput*	300MB/s	600MB/s	1200MB/s	3938MB/s

*This maximum throughput is only theoretical. Real speed may be slower depending on the disc type, controller, driver, or the type of data being moved. One file, for example, gets transferred faster than a folder full of small files.

Additional Drive Selection Parameters

Height - 7 and 9.5mm drive heights are used in laptops. You can fit in a smaller drive with the right adapter (racks and trays). However, if you only have a 7mm slot, make sure to buy a drive with the right height.
RAID - disk mirroring ensures greater reliability. RAID drives are ready for use in data storage (NAS), servers, and other installations where heavy duty, non-stop operation is expected.