Comparison WD Blue WD5000AZLX 500 GB

32/7200

vs WD Caviar Green WD5000AADS 500 GB

— SATA. Nowadays, it is the most popular interface for connecting internal hard drives. The first version of SATA provides a data transfer rate of about 1.2 Gbps, SATA 2 has a practical data transfer rate of about 2.4 Gbps (300 MB/s), and the most advanced generation SATA 3 offers a speed of 4.8 Gbps (600 MB/s).

— eSATA. A modification of the SATA interface designed for connecting external hard drives; it is not compatible with internal SATA. The practical data transfer rate is similar to SATA 2 and amounts to about 2.4 Gbps (300 MB/s).

— SAS. A modification of the SCSI interface, provides data transfer speeds up to 6 Gbps (750 MB/s). It is predominantly used in servers, and is practically not used in desktop PCs and laptops.

— USB-A 2.0. The earliest of the USB standards found in modern hard drives, exclusively external ones (see "Design"). It involves connecting to a traditional full-sized USB-A port, allows data transfer speeds up to 480 Mbps, and has fairly low power supply, which often requires additional power for drives with this type of connection. In light of all this and the emergence of more advanced standards like USB 5Gbps / 10 Gbps, USB 2.0 is considered outdated today and is found very rarely, mainly in inexpensive and early models of drives. However, a drive with this interface can also be connected...to a newer USB-A port—provided the connectors match.

— USB-A 5Gbps (previously known as USB 3.2 gen1 and USB 3.0). The standard for connecting external HDDs, which replaced the aforementioned USB 2.0. It uses the traditional full-sized USB-A connector, provides data transfer speeds up to 4.8 Gbps (600 MB/s), and has higher power supply, which makes it easier for such drives to manage without external power. However, for the same reason, attention is needed when connecting USB 5Gbps drives to older USB 2.0 connectors—as such a connector may not have enough power to supply the newer drive.

— USB-A 10Gbps. A further development of the USB 5Gbps standard (formerly known as USB 3.2 gen2 and USB 3.1). In this version, the maximum data transfer speed has been increased to 10 Gbps, and the power supply can reach up to 100W (with USB Power Delivery support). Meanwhile, drives with this type of connection can work with older versions of full-sized USB-A connectors—provided there is enough power supply.

— USB-C 5Gbps (previously known as USB-C 3.2 gen1 and USB-C 3.0). Connection through a USB-C type connector, corresponding to the capabilities of USB 5Gbps. The possibilities are described above, and the difference from USB-A 5Gbps in this case lies only in the type of connector: it is a relatively small (slightly larger than microUSB) socket with a reversible design. Due to its compact size, USB-C is found in both full-sized PCs and laptops, as well as compact gadgets such as smartphones and tablets; some drives with this connection initially allow "mobile" use.

— USB-C 10Gbps (previously known as USB-C 3.2 gen2 and USB-C 3.1). An update and improvement of the above-mentioned USB-C 5Gbps—the same USB-C connector and an increased data transfer speed up to 10 Gbps (as in "regular" USB-A 10Gbps).

— Thunderbolt. A high-speed interface for connecting external peripherals. It is primarily used in Apple computers and laptops, although it is also found in technologies from other manufacturers. Note that in modern HDDs, two versions of Thunderbolt are mainly encountered, differing in not only speed but also connector: Thunderbolt v2 (up to 20 Gbps) uses a miniDisplayPort type plug, and Thunderbolt v3 (up to 40 Gbps) uses a USB-C type plug (see above). In light of this, in some hard drives, USB-C and Thunderbolt connections are implemented through a single hardware connector that automatically determines which computer input the device is connected to.

— CMR(Conventional Magnetic Recording) is a classic method of magnetic recording, characterized by high data access speed. CMR hard drives are used in systems where it is important to provide high (as far as possible) data read/write speed. These are user computers, security video surveillance systems, etc. The main disadvantage of CMR hard drives is the high complexity of creating volume drives, which is reflected in their price. Additionally, HDDs with CMR technology are quite “gluttonous” in terms of power supply.

— SMR(Shingled Magnetic Recording) — a promising technology for magnetic recording, which is called "tiled". SMR allows to achieve high data density, which in turn increases the capacity of memory drives and lowers their market value. SMR hard drives have slow rewriting speed, which makes such memory drives poorly suited for use in client computer systems. But they have proven themselves well when working as part of data processing centers, archives and similar systems for which low write / rewrite speed is not critical. However, some companies still produce SMR solutions for personal and even mobile systems. These HDDs use an optimized write/rewrite technology called Drive-Managed SMR (DM-SMR).

For drives used in a PC (see "Intended use"), 5400 rpm(normal) and 7200 rpm(high) are considered standard speeds. There are also more specific options, including models with the ability to adjust the speed depending on the load. In server HDDs, in turn, higher speeds can be used — 10,000 rpm and even 15,000 rpm.

The speed of data transfer between the disk and client devices is determined by the type of drive, spindle speed, memory buffer size and connection connectors. The last parameter is the most important, since it is impossible to exceed the bandwidth of a particular interface.

The number of platters provided in the design of the hard drive.

Physically, a hard disk consists of one or more platters, on which information is recorded. Several plates can be provided in order to achieve the desired volume without increasing the form factor. At the same time, it is also necessary to install an appropriate number of reading heads in such a drive, which complicates the design, reduces its reliability, and increases the cost. Therefore, manufacturers choose the number of plates based on a reasonable compromise between these points, and for selection, this parameter is more of a reference than practically significant.

The time it takes for the hard disk mechanics to find random requested data to read. For each specific case, the search time is different, as it depends on the location of the data on the surface of the disk and the position of the read head, therefore, the average value is indicated in the characteristics of hard drives. The lower the average seek time, the faster the disk works, all other things being equal.

The amount of power consumed by the disk when reading and writing information. In fact, this is the peak power consumption, it is in these modes that the drive consumes the most energy.

HDD power consumption data is needed primarily to calculate the overall system power consumption and power supply requirements for the system. In addition, for laptops that are planned to be used often "in isolation from outlets", it is advisable to choose more economical drives.

The amount of power consumed by the disk "idle". In the on state, the disk platters rotate regardless of whether information is being written or read or not — maintaining this rotation takes the energy consumed while waiting.

The lower the power consumption while waiting, the more economical the disk is, the less energy it consumes. At the same time, we note that in fact this parameter is relevant mainly when choosing a drive for a laptop, when energy efficiency is crucial. For stationary PCs, “idle” power consumption does not play a special role, and when calculating the requirements for a power supply, it is necessary to take into account not this indicator, but the power consumption during operation (see above).

A parameter that determines the resistance of the hard drive to drops and shocks during operation (that is, in the on state). Shock resistance is measured in G — units of overload, 1 G corresponds to the usual force of gravity. The higher the G number, the more resistant the disc is to various kinds of concussions and the less likely it is to be damaged, say, in the event of a fall. This setting is especially important for external drives and drives used in laptops.