Published hard drive.
We also did not ignore the HDD interface, where the main features and differences were discussed SATA interface and outdated IDE. And of course we haven’t forgotten, perhaps the most important characteristic - this hard drive capacity.
In this article we will talk about the remaining characteristics hard drives, which are no less important than the above.
Hard drive form factor
On this moment, two widespread rigid form factor disks are 2.5 and 3.5 inches. The form factor largely determines the dimensions of hard drives. By the way, in HDD 3.5” accommodates up to 5 drive platters, and 2.5” accommodates up to 3 platters. But in modern realities, this is not an advantage, since the developers have determined for themselves that installing more than 2 platters in ordinary high-performance hard drives is not advisable. Although, the 3.5” form factor does not intend to give up at all and, in terms of demand, confidently outweighs 2.5” in the desktop segment.
That is, for a desktop system, for now it makes sense to purchase only 3.5”, since among the advantages of this form factor, one can note a lower cost per gigabyte of space, with a larger volume. This is achieved due to a larger platter, which, with the same recording density, can accommodate a larger volume of data than 2.5”. Traditionally, 2.5” has always been positioned as a form factor for laptops, largely due to its dimensions.
There are other form factors. For example, in many portable devices ah, 1.8” form factor hard drives are used, but we will not dwell on them in detail.
Hard drive cache size
Cache memory- this is a specialized RAM that acts as an intermediate link (buffer) for storing data that has already been read from hard drive, but have not yet been submitted directly for processing. The very presence of the buffer was caused by a significant difference in operating speed between the rest of the system components and the hard drive.
As such, a characteristic of HDD cache memory is volume. At the moment, the most popular hard drives are those with 32 and 64 MB buffers. In fact, buying a hard drive with a large amount of cache memory will not double the performance as it might seem based on classical arithmetic. Moreover, testing has shown that the advantage of hard drives with a 64 MB cache manifests itself quite rarely and only when performing specific tasks. Therefore, if possible, it is worth purchasing a hard drive with a larger cache memory, but if this comes at a significant cost to the price tag, then this is not the parameter that you should focus on first.
Random access time
The hard drive random access time indicator characterizes the time during which the hard drive is guaranteed to perform a read operation anywhere on the hard drive. That is, in what period of time will the reading head be able to reach the most distant hard sector disk. This largely depends on the previously discussed characteristics of the spindle speed of the hard drive. After all, the higher the rotation speed, the faster the head can reach the desired track. In modern hard drives this figure ranges from 2 to 16 ms.
Other HDD characteristics
Now let’s briefly and briefly list the remaining characteristics of hard drives:
- Energy consumption – hard drives consume very little. Moreover, the maximum power consumption is often indicated, which occurs only at intermediate stages of operation during peak load. On average it is 1.5-4.5 W;
- Reliability (MTBF) – the so-called time between failures;
- Data transfer speed – from the external zone of the disk: from 60 to 114 Mb/s, and from the internal zone – from 44.2 to 75 Mb/s;
- Number of input/output operations per second (IOPS) – for modern hard drives this figure is about 50/100 op/s, with random and sequential access.
So we looked at all the characteristics of hard drives using a small series of articles. Naturally, many parameters intersect and, to some extent, influence each other. But, on the basis of information regarding all these parameters, you can model a future device for yourself, and when choosing, clearly understand which model should be given preference in your particular case.
But such toys can be made from old hard drives, or rather from the components of a hard drive. For example, the wheels are made from a spindle motor of a hard drive, which drives an axle with a readout head.
A hard drive (hard drive, Hard Disk Drive, HDD) is a device designed to store all information on a computer. All movies, music, photos, documents, all system files are stored on it. Therefore, to this device I have a special relationship, I always carefully monitor his condition and constantly make backup copies of important information so as not to lose it. I will definitely tell you how to make backup copies in one of my notes.
If your computer suddenly does not turn on, do not be alarmed, most likely all the information remains intact. If you wish and have certain skills, all information from one hard drive can be copied to another. You can read more about this in my article on how to copy data from a hard drive or how to “clone a disk.”
So, let's start looking at the characteristics of the hard drive.
Here are the main ones:
- hard drive type;
- storage volume;
- disk form factor;
- interface;
- buffer memory volume;
I have listed as many as 5 characteristics, but we will deal with them quickly, since there is nothing complicated about them, and some will already be familiar to you from previous lessons.
Drive type
There are two types of drives:
1) HDD– Hard disk drive is the most common type of drive, which consists of metal alloy plates coated with a layer of ferromagnetic material. All information is recorded on these plates, which rotate at a very high speed - 5400/7200 rpm. In this case, information is read by the reading head without touching the surface of the plates, thereby not damaging it and increasing the service life of the device.
These devices are used in the vast majority of computers because their cost is low.
2) SSD– Solid state drive – a storage device based on memory chips. SSD drives appeared relatively recently and quickly took their place in the market. Currently, solid-state drives are used in compact devices: laptops, netbooks, communicators and smartphones.
I will give the disadvantages and advantages of SSD drives.
Flaws:
- limited number of rewrite cycles. Depending on the type of memory cells used, from 10,000 to 100,000 times;
- compatibility problem SSD drives with some versions of Windows operating systems that do not take into account the specifics of SSD drives, thereby reducing their service life;
- the price of a gigabyte of SSD drives is significantly higher than the price of a gigabyte of HDD;
- impossibility of recovering deleted information using recovery utilities;
Advantages:
- absence of moving parts, and, as a result, high mechanical resistance;
- high read/write speed;
- low power consumption;
- complete absence of noise due to the absence of moving parts and cooling fans;
- stability of file reading time, regardless of their location or fragmentation;
- small dimensions and weight;
- Great potential for the development of storage devices and production technologies.
Despite the many advantages of SSD drives, I personally still use traditional HDDs. Their productivity is enough for me to carry out any tasks, and time-tested technologies are reliable enough to trust them with important information. Well, of course, my choice is influenced by the cost of drives.
Storage capacity
Obviously, the larger the hard drive, the more important information we can place it on it. The capacity of hard drives is measured in billions of bytes (GB - gigabytes) or trillions of bytes (TB - terabytes). The capacity of modern drives reaches up to 4TB in one device, but we must remember that if desired, we can install several such hard drives in the system.
Of course, the higher the storage capacity, the more expensive its cost, and the cost of SSDs is directly proportional to their capacity, while the cost of traditional hard drives depends on the number of platters and grows more slowly as the storage capacity increases.
Form factor
The form factor determines the size of the drive. There are 3 sizes of modern hard drives: 1.8”, 2.5”, 3.5”.
HDD hard drives can have sizes of 2.5 and 3.5 inches. 3.5-inch drives are installed inside the system unit, and 2.5-inch drives are used in laptops and external hard drives.
SSD drives can have a form factor of 2.5 inches or 1.8 inches. As I wrote earlier, they are used in laptops, netbooks, communicators and smartphones.
Interface
For order, we list all the popular interfaces:
SATA, SATA2, SATA3;
Now a few words about each of the connectors.
IDE is an old connector that can be easily distinguished from the others by its wide cable from HDD to motherboard. Modern computers do not use such a connector, but I can’t help but mention it, since it is still found in older computers. The IDE connector is becoming less and less common on motherboards.
The IDE was replaced by the SATA connector, which also became outdated and was in turn replaced by SATA2 and now the SATA3 connector is increasingly used. I combined all the connectors into one item, since they are all identical in shape and differ only in the data transfer speed - 1.5 Gb/s, 3 Gb/s, 6 Gb/s, respectively. But it should be remembered that in order for a hard drive with a connector, for example, SATA3, to work at maximum efficiency, the motherboard must also have a SATA3 connector installed. If a SATA2 connector is installed on the motherboard, then a hard drive with a SATA3 interface will still work, but information will be transferred at a speed of 3 Gb/s.
Although, the situation with a transfer speed of 6 Gb/s is more like a marketing ploy. The fact is that the vast majority of modern drives still cannot completely fill a 3 GB/s channel, since the speed of reading and writing to the disk is significantly lower than this speed.
And the last interface is micro-SATA. This connector appeared quite recently; 1.8” SSD drives are connected through it. Micro-SATA connectors have already begun to appear on modern motherboards, but even if the motherboard you have chosen does not have such an interface, the drive can be connected via a micro-SATA to SATA adapter.
Buffer memory capacity (CACH)
Let's figure out what it is. A buffer is an intermediate memory designed to smooth out differences in read/write and transfer speeds across the interface. In modern disks it usually varies from 8 to 128 MB.
For you, my readers, I will clarify that the buffer volume does not provide a significant increase in system performance, so you should not pay attention to it as a key element. Any noticeable difference in time can be obtained by copying very large amounts of information.
By tradition, we will consider the railway markings from the supplier’s catalog.
The article turned out to be quite long, but I hope that someone will appreciate it, and my efforts will not be in vain.
Well, that's all for today. So, slowly, we learned another lesson that should help in achieving our common success. I hope this material will help you make the right choice.
Greetings, dear readers! In normal people, whose consciousness has not yet been clouded by acquaintance with computer technologies, when you hear the word “Winchester,” the first association that arises is the famous hunting rifle, extremely popular in the USA. Computer scientists have completely different associations - that’s what most of us call a hard drive.
In today's publication we will look at what a buffer is. hard memory disk, what it is needed for and how important this parameter is for performing various tasks.
How a hard drive works
HDD is essentially a drive on which everything is stored. user files, as well as the operating system itself. Theoretically, you can do without this detail, but then the OS will have to be loaded from removable media or over a network connection, and working documents will have to be stored on a remote server.
The base of the hard drive is a round aluminum or glass plate. It has a sufficient degree of rigidity, which is why the part is called a hard drive. The plate is coated with a layer of ferromagnetic material (usually chromium dioxide), the clusters of which remember one or zero through magnetization and demagnetization. There can be several such plates on one axis. A small high-speed electric motor is used for rotation.
Unlike a gramophone, in which the needle touches the record, the read heads are not adjacent to the disks, leaving a distance of several nanometers. Due to the absence of mechanical contact, the service life of such a device increases.
However, no part lasts forever: over time, the ferromagnet loses its properties, which means it leads to a loss of hard disk space, usually along with user files. 
That is why, for important or dear data (for example, a family photo archive or the fruits of the computer owner’s creativity), it is recommended to do backup copy, or better yet several at once.
What is cache
Buffer memory or cache is a special type of random access memory, a kind of “layer” between the magnetic disk and the PC components that process the data stored on the hard drive. It is designed for smoother reading of information and storage of data that is currently most often accessed by the user or the operating system.
What the size of the cache affects: the larger the amount of data that fits in it, the less often the computer has to access the hard drive. Accordingly, the performance of such a workstation increases (as you already know, in terms of performance, the magnetic disk of a hard drive is significantly inferior to a RAM chip), as well as, indirectly, the service life of the hard drive.
Indirectly because different users use the hard drive in different ways: for example, a movie lover who watches them in an online cinema via a browser will theoretically have a hard drive that will last longer than a movie fan who downloads movies by torrent and watches them using a video player.
Can you guess why? That's right, due to the limited number of cycles of rewriting information on the HDD. 
How to view the buffer size
Before you can see the cache size, you will have to download and install the HD Tune utility. After starting the program, the parameter of interest can be found in the “Information” tab at the bottom of the page.
Optimal sizes for various tasks
A logical question arises: which buffer memory is best for home computer and what does this give in practical terms? Naturally, preferably more. However, the hard drive manufacturers themselves impose restrictions on the user: for example, a hard drive with 128 MB of buffer memory will cost significantly above average.
This is the cache size that I recommend focusing on if you want to build a gaming computer that will not become outdated in a couple of years. For simpler tasks, you can get by with simpler characteristics: 64 MB is enough for a home media center. And for a computer that is used purely for surfing the Internet and running office applications and simple flash games, a 32 MB buffer memory is quite enough.
As a “golden mean,” I can recommend the Toshiba P300 1TB 7200rpm 64MB HDWD110UZSVA 3.5 SATA III hard drive - the cache size here is average, but the capacity of the hard drive itself is quite enough for a home PC. Also, to complete the picture, I recommend that you read the publications of disks and, as well as which ones are on hard disks.
It is known that hard drives are equipped with their own buffer memory of a relatively small size. The buffer is used as an on-chip cache for read and write operations, allowing for optimized performance and minimization of time-consuming platter accesses. For example, when there is free space in the buffer, the controller can temporarily place data that needs to be written there and wait for a convenient moment when there are no requests from the system (host). When executing read requests, the controller stores the last data read in case the host requests it again - then there is no need to access the disk again. The controller often performs read ahead to try to predict the host's next requests, and the data read in this way is also buffered. It turns out that the buffer is constantly used by the hard drive, and its role is very important.
Hard drive manufacturers have always strived to increase the amount of buffer memory. Today this is easier to do, since conventional microcircuits are synchronous dynamic memory(SDRAM), and it is they that are used in hard drives, they are quite inexpensive. In the late 90s, desktop hard drives were equipped with a 512 KB buffer, then most models received 2 MB of memory, and today the most common hard drives are with an 8 MB buffer. However, there is no limit to perfection: WD has updated its mass line of Caviar SE hard drives, adding Caviar SE16 models to it. Their main difference, as you may have guessed, is the doubled volume of buffer memory.
Why do we need 16 MB?
It would seem that the larger the amount of buffer memory, the higher the performance of the hard drive. The controller will be able to place more data in the buffer, which means it will access the magnetic plates less often. However, not everything is as simple as it seems at first glance.
Caching algorithms typically use an associative search method to determine whether the required data is present in the buffer. To increase the amount of data stored in the cache, you must either increase the size of one block (cache line) or increase the number of lines. And this is fraught with the appearance of additional problems with associative search and data exchange with the cache.
However, for a hard drive, caching speed is not so important, since in any case it is negligible compared to the delays when accessing magnetic media. Whether the controller really needs additional memory is another matter. It is possible that the hard drive is not so busy with work that it fully uses all the available buffer space. For example, when simply copying and loading programs, there is no need to cache anything, since the data is read only once. But when working in a server environment, when requests arrive chaotically and continuously, big buffer– a significant plus for the hard drive. Actually, that’s why server hard drives were always equipped with a buffer of at least 8 MB. But in a desktop computer, read and access speed is more important than buffering efficiency.
(However, let's not forget about NCQ technology. With its help, the hard drive can manage the queue of requests, changing the order in which they are served. Since in this case the nature of access to the media also changes, additional buffering can help improve performance. But alas, most users still still doesn’t know how to use NCQ, since support from the hard drive alone is not enough).
It turns out that a large buffer size is unlikely to have a significant impact on the overall speed. Installing a higher capacity chip is not enough to improve performance. Developers should not only rework the microcode, but also improve the media read/write speed and interface throughput.
Caviar SE16. Design Features
We were able to compare the WD2500KS model, part of the Caviar SE16 line, with the WD2000JS model from the "standard" Caviar SE line. As it turned out, they have a minimum of differences: the markings of the HDA, connectors, and electronics board are the same. Even the microcode version is the same. Consequently, the developers from WD used the previous technology, simply replacing one memory chip with another.
For those who are not aware of the features of WD hard drives, we will inform you the following. This manufacturer uses only proven technologies and takes special care to protect disks from damage. The design of the HDA is standard: the massive body and the flat top cover are hermetically connected, and there is a ventilation hole on the top of the cover. But the electronics board is traditionally turned over with the microcircuits inward and pressed against the body; there is a thermally conductive gasket. This technique allows you to protect microcircuits from overheating and external influences. There are two power connectors - a standard 4-pin and a new flat one, in accordance with Serial ATA requirements. To protect the Serial ATA interface connector from accidental disconnection, WD suggests using a special SecureConnect cable with latches.
The Caviar SE16 series is available only with support for the Serial ATA interface. Moreover, the hard drive controller supports “second speed” 3 GB/s (300 MB/s). Other technologies, in particular NCQ, have not yet been implemented - here WD lags behind other manufacturers.
Declared parameters of WD Caviar SE/SE16 hard drives |
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Marking |
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Spindle rotation speed, rpm |
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Recording density, GB per platter |
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Cache buffer volume, MB |
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Bearings |
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Interface |
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NCQ support |
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Capacity range |
120, 160, 200, 250 |
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Int. data exchange speed, Mbit/s |
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Average access speed: average, ms |
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- by maximum radius, ms |
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- transition between tracks, ms |
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-write access speed, ms |
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Impact resistance (offline), G |
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Impact resistance (online), G |
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Noise level when idle, dB |
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Noise level during positioning, dB |
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Testing
Hard drives from three manufacturers took part in the testing: WD, Seagate and Samsung. At the time of writing, their products were presented in a wide range. A copy of the one in question review of hard The Caviar SE16 series disk had the following parameters:
- marking WD2500KS-00MJB0;
- volume 250 GB;
- microcode version 02.01C03;
- silent positioning mode (AAM) is disabled (0FEh).
We will compare the following hard drives with it:
- Caviar SE, from the line with an 8 MB buffer, 200 GB capacity:
- marking: WD2000JS-00MHB0;
- buffer volume – 8 MB;
- interface – Serial ATA 3 Gbit/s, NCQ not supported;
- microcode version – 02.01C03 (same);
- Quiet positioning mode (AAM) is disabled (0FEh).
- Samsung SpinPoint P120, 200 GB:
- marking SP2004C;
- buffer volume – 8 MB;
- interface – Serial ATA 3 Gbit/s, NCQ supported;
- microcode version – VM100-33;
- "quiet" positioning mode is enabled (code 00h).
- Seagate Barracuda 7200.8, 200 GB:
- marking ST3200826AS;
- buffer volume – 8 MB;
- interface – Serial ATA 1.5 Gbit/s, NCQ supported;
- microcode version – 3.03;
- "quiet" positioning mode is blocked (control is not available).
Seagate and Samsung hard drives have higher recording densities than WD Caviar. In addition, Seagate has a higher stated positioning speed (8 ms versus 8.9 ms for Samsung and WD), and Samsung work It's quieter. That is, WD formally have no advantages over drives from other manufacturers. But in practice the opposite may be true.
Hard drives were connected to the second port of the Serial ATA controller built into the ICH5 southern hub Intel chipset 865G. Unfortunately, the 865 series chipsets do not support 3 Gbit/s speeds and NCQ technology, so they cannot fully reveal the capabilities of modern hard drives. Other test configuration parameters:
- host hard drive from which the OS was loaded and tests were run – Seagate Barracuda 7200.7 PATA 80 GB;
- CPU Intel Pentium 4 2.80 (800 MHz bus);
- motherboard Intel D865GBF (Intel 865G);
- memory 2 x 256 DDR400, dual-channel mode enabled;
- GeForce FX 5600 video card;
- The hard drives were installed in a 2.5-inch cage of the Inwin J551 case; no special cooling was used.
Low Level Tests
Using programs that work directly with the disk allows you to measure the theoretical parameters of the hard drive - random access speed, average (sustained) read and write speed, lazy write efficiency. At the same time, the influence of caching algorithms is minimal, since access is carried out continuously and according to a simple scheme.
Low-level parameters were calculated using the following programs:
- IOMeter 2004.07.30;
- HDTach 2.68;
- HDTach 3.0.1.0;
- Winbench 2.0 (the disk was formatted for one large NTFS partition).
Access speed turned out to be higher for Caviar, since WD hard drives do not use positioning delay algorithms (AAM). Seagate, despite its excellent reported numbers, came in last. Oddly enough, the Caviar SE16 was slightly inferior to its brother (0.3 ms), which can be explained either by the natural difference in technological parameters (after all, the mechanics have some deviations in one direction or another), or by the influence of the third plate (the greater the number of heads, the more delay for their switching). Of course, the differences are actually very small, and we won’t talk about a serious lag in the Caviar SE16. In terms of write access speed, WD hard drives are equal, providing twice the speed of read access. This is explained by the influence of the delayed recording algorithm.
By sequential read/write speed The Caviar SE16, on the contrary, was slightly ahead of the Caviar SE. But they were overtaken by the Seagate hard drive (+10%), which is natural due to the use of a higher recording density, and Samsung, on the contrary, was just as far behind.
A more accurate analysis of read/write speed can be done by IOMeter. If other programs work with 64 KB blocks, IOMeter can vary the block size.
Seagate is the leader in reading: it copes significantly better (+20%) with small and large blocks. Samsung, as it turns out, works very poorly with small blocks. And WD performed excellently in write tests, beating Seagate when working with blocks less than 64 KB.
The Winbench’99 program, despite its venerable age, quite accurately plots sequential readings.
Both WD drives have the same graph shape, with no peaks or valleys, indicating high read stability. The Caviar SE16's graph is more elongated, which is due to its larger capacity. Increasing the scale of the graph allows us to consider short-term but strong speed dips in Seagate and Samsung (the operation of ECC error correction algorithms, delays in switching heads and changing tracks) and the absence of such in WD. And even though the recording density of WD is worse, the proven production technology has its advantages - higher stability.
Application simulation
The Workstation IOMeter test template allows you to generate a load on the disk subsystem that is close to real (statistics were collected using the Winstone 2002 Content Creation test). So, this test is more sensitive to access speed than to read/write speed, plus it takes into account the operation of caching algorithms, since requests arrive with increasing queue depth.
According to the data obtained, both WD drives slightly outperformed Samsung and literally crushed Seagate. Caviar SE is again slightly better than Caviar SE16, since they have a slight difference in access speed.
We had high hopes for the PCMark05 test, since it should show the advantage of a large cache buffer. This test uses patterns recorded using the Intel IPEAK SPT test suite to perform specific tasks. Consequently, PCMark05 can more or less plausibly simulate the operation of a hard drive in real conditions.
So, if in terms of speed Windows boot XP, copying files and scanning for viruses, WD hard drives are almost the same, but in terms of application loading speed and access to data while applications are running, the Caviar SE16 is 10-15% faster than the Caviar SE, not to mention Samsung and Seagate.
The advantage of a hard drive with a large buffer is also noticeable in the Winstone test, especially if it is used file system FAT32.
conclusions
The test results prove that there is a positive effect from increasing the buffer. It is small, within 10-15%, and only appears when the hard drive is operating under conditions close to real ones. In low-level tests there is practically no difference, which is consistent with theory. The same theory suggests that with an increase in interface bandwidth and recording density, as well as with the introduction of disk access optimization technologies, the buffer volume will have to be increased. Therefore, the developers from WD were a little hasty; however, it is better to work on developing the technology now than to catch up with competitors later.
Choosing a hard drive for a PC is a very important task. After all, it is the main repository of both official and your personal information. In this material we will talk about the key characteristics of HDD that you should pay attention to when purchasing a magnetic drive.
Introduction
When buying a computer, many users often focus their attention on the characteristics of its components such as a monitor, processor, and video card. And such an integral component of any PC as a hard drive (in computer slang - a hard drive), buyers often purchase, guided only by its volume, practically neglecting other important parameters. However, it should be remembered that a competent approach to choosing a hard drive is one of the guarantees of comfort during further work at the computer, as well as saving money, which we are so often constrained by.
A hard drive or hard disk drive (HDD) is the main data storage device in most modern computers, which stores not only the information the user needs, including movies, games, photos, music, but also the operating system, as well as everything installed programs. Therefore, strictly speaking, the choice of a hard drive for a computer should be treated with due attention. Remember that if any PC element fails, it can be replaced. The only negative point in this situation is the additional financial costs of repairs or purchasing a new part. But a hard drive failure, in addition to unforeseen costs, can lead to the loss of all your information, as well as the need for re-installation operating system and all required programs. The main purpose of this article is to help novice PC users choose a hard drive model that would best meet the requirements that specific “users” have for their computer.
First of all, you should clearly decide in which computer device the hard drive will be installed and for what purposes you plan to use this device. Based on the most common tasks, we can conditionally divide them into several groups:
- A mobile computer for general tasks (working with documents, surfing the World Wide Web, processing data and working with programs).
- A productive mobile computer for games and resource-intensive tasks.
- Desktop computer for office tasks;
- Productive desktop computer(working with multimedia, games, audio, video and image processing);
- Multimedia player and data storage.
- For assembling an external (portable) drive.
In accordance with one of the listed options for using your computer, you can begin to select a suitable hard drive model based on its characteristics.
Form factor
Form factor is the physical size of the hard drive. Today, most drives for home computers are 2.5 or 3.5 inches wide. The first, which are smaller, are intended for installation in laptops, the second - in stationary system units. Of course, if desired, a 2.5-inch drive can be installed in a desktop PC.
There are also smaller magnetic drives with sizes of 1.8”, 1” and even 0.85”. But these hard drives are much less common and are aimed at specific devices, such as ultra-compact computers (UMPCs), digital cameras, PDAs and other equipment where small dimensions and weight of components are very important. We will not talk about them in this material.
The smaller the drive, the lighter it is and the less power it requires to operate. Therefore, hard drives of the 2.5" form factor have almost completely replaced 3.5-inch models in external drives. After all, large external drives require additional power from an electrical outlet to operate, while the younger brother is content only with power from the USB ports. So if you decide to assemble a portable drive yourself, it is better to use a 2.5-inch HDD for these purposes. This will be a lighter and more compact solution, and you won’t have to carry the power supply with you.
As for installing 2.5-inch drives in a desktop system unit, then this solution looks ambiguous. Why? Read on.
Capacity
One of the main characteristics of any drive (in this regard, a hard drive is no exception) is its capacity (or volume), which today in some models already reaches four terabytes (one terabyte has 1024 GB). Just 5 years ago, such a volume might have seemed fantastic, but current OS builds, modern software, videos and photos high resolution, as well as three-dimensional computer video games, having a fairly significant “weight”, require a large hard drive capacity. Thus, some modern games require 12 or even more gigabytes of free space on your hard drive to function properly, and an hour and a half HD movie may require more than 20 GB of storage.
Today, the capacity of 2.5-inch magnetic media ranges from 160 GB to 1.5 TB (the most common sizes are 250 GB, 320 GB, 500 GB, 750 GB and 1 TB). 3.5" disks for desktops are more capacious and can store from 160 GB to 4 TB of data (the most common sizes are 320 GB, 500 GB, 1 TB, 2 TB and 3 TB).
When choosing HDD capacity, consider one important detail - the larger the hard drive capacity, the lower the price of 1 GB of information storage. For example, a 320 GB desktop hard drive costs 1,600 rubles, 500 GB - 1,650 rubles, and 1 TB - 1,950 rubles. We calculate: in the first case, the cost of a gigabyte of data storage is 5 rubles (1600 / 320 = 5), in the second - 3.3 rubles, and in the third - 1.95 rubles. Of course, such statistics do not mean that it is necessary to buy a very large capacity disk, but in in this example It is very clear that buying a 320 GB disk is not practical.
If you plan to use the computer mainly for solving office tasks, then a hard drive with a capacity of 250 - 320 GB, or even less, will be more than enough for you, unless, of course, there is a need to store huge documentation archives on the computer. At the same time, as we noted above, buying a hard drive with a capacity below 500 GB is unprofitable. Saving from 50 to 200 rubles, you end up with a very high cost of one gigabyte of data storage. Moreover, this fact applies to drives of both form factors.
Do you want to build a gaming or multimedia PC for working with graphics and video, do you plan to download new films and music albums to your hard drive in large quantities? Then it is better to choose a hard drive with a capacity of at least 1 TB for a desktop PC and at least 750 GB for a mobile one. But, of course, the final calculation of the hard drive capacity must meet the specific needs of the user, and in this case we provide only recommendations.
Separately, it is worth noting data storage systems (NAS) and multimedia players that have become popular. As a rule, large 3.5” drives are installed in such equipment, preferably with a capacity of at least 2 TB. After all, these devices are focused on storing large amounts of data, which means that the hard drives installed in them must be capacious with the lowest price for storing 1 GB of information.
Disk geometry, platter and recording density
When choosing a hard drive, you should not blindly focus only on its total capacity, according to the principle “the more, the better.” There are other important characteristics, including: recording density and the number of platters used. After all, not only the volume of the hard drive, but also the speed of writing/reading data directly depends on these factors.
Let's make a small digression and say a few words about design features modern hard drives magnetic disks. Data is recorded in them on aluminum or glass disks, called platters, which are coated with a ferromagnetic film. Reading heads located on special rotating positioner brackets, sometimes called “rocker arms,” are responsible for writing and reading data from one of thousands of concentric tracks located on the surface of the plates. This procedure occurs without direct (mechanical) contact between the disk and the head (they are located at a distance of about 7-10 nm from each other), which ensures protection from possible damage and long service life of the device. Each plate has two working surfaces and is served by two heads (one on each side).
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To create address space, the surface of magnetic disks is divided into many circular areas called tracks. In turn, the tracks are divided into equal segments - sectors. Due to this ring structure, the geometry of the plates, or rather their diameter, affects the speed of reading and writing information.
Closer to the outer edge of the disk, the tracks have a larger radius (longer) and accommodate a larger number of sectors, which means more information that can be read by the device in one revolution. Therefore, on the outer tracks of the disk, the data transfer speed is higher, since the reading head in this area covers a greater distance in a certain time period than on the inner tracks, which are located closer to the center. Thus, disks with a diameter of 3.5 inches have higher performance than disks with a diameter of 2.5 inches.
A hard drive can contain several platters at once, each of which can store a certain maximum amount of data. In fact, this determines the recording density, measured in gigabits per square inch (Gbit/in2) or gigabytes per platter (GB). The larger this value, the more information is placed on one track of the platter, and the faster the recording is carried out, as well as the subsequent reading of information arrays (regardless of the speed of rotation of the disks).
The total volume of the hard drive is the sum of the capacities of each of the plates placed in it. For example, the first commercial drive with a capacity of 1000 GB (1TB), which appeared in 2007, had as many as 5 plates with a density of 200 GB each. But technological progress does not stand still, and in 2011, thanks to the improvement of perpendicular recording technology, Hitachi introduced the first 1 TB platter, which is widely used in modern large-capacity hard drives.
Reducing the number of platters in hard drives has a number of important advantages:
- Reduced data reading time;
- Reduced energy consumption and heat generation;
- Increased reliability and fault tolerance;
- Reducing weight and thickness;
- Cost reduction.
Today on the computer market there are simultaneously models of hard drives that use platters with different recording densities. This means that hard drives of the same volume can have completely different numbers of platters. If you are looking for the most efficient solution, then it is better to choose a HDD with the least number of magnetic platters and a high recording density. But the problem is that in almost no computer store you will not find the values of the above-described parameters in the descriptions of disk characteristics. Moreover, this information is often not available even on the official websites of manufacturers. As a result, for ordinary ordinary users, these characteristics are not always decisive when choosing a hard drive, due to their inaccessibility. However, before purchasing, we recommend that you definitely find out the values of these parameters, which will allow you to select a hard drive with the most advanced and modern characteristics.
Spindle speed
The performance of a hard drive directly depends not only on the recording density, but also on the rotation speed of the magnetic disks located in it. All plates located inside the hard drive are rigidly attached to its internal axis, called the spindle, and rotate with it as a single unit. The faster the plate rotates, the sooner a sector will be found that should be read.
In stationary home computers, hard drive models are used that have an operating speed of 5400, 5900, 7200, or 10000 rpm. Units with a spindle speed of 5,400 rpm are typically quieter and generate less heat than their high-speed competitors. Winchesters with higher speeds, in turn, differ better performance, but at the same time more energy-consuming.
For a typical office PC, a drive with a spindle speed of 5400 rpm will be sufficient. Also, such disks are well suited for installation in multimedia players or data warehouses, where the important role is played not so much by the speed of information transfer, but reduced energy consumption and heat dissipation.
In other cases, in the vast majority, disks with a platter rotation speed of 7200 rpm are used. This applies to both mid- and high-end computers. The use of HDDs with a rotation speed of 10,000 rpm is relatively rare, since such models of hard drives are very noisy and have a fairly high cost of storing one gigabyte of information. Moreover, recently, users increasingly prefer to use solid-state drives instead of high-performance magnetic disks.
In the mobile sector, where 2.5-inch drives reign, the most common spindle speed is 5400 rpm. This is not surprising, since low power consumption and low level heating parts. But we haven’t forgotten about the owners of productive laptops - there is a big choice models with a rotation speed of 7200 rpm and even several representatives of the VelociRaptor family with a rotation speed of 10000 rpm. Although the feasibility of using the latter even in the most powerful mobile PCs is highly questionable. In our opinion, if you need to install a very fast disk subsystem, it is better to pay attention to solid-state drives.
Connection interface
Almost all modern models of both small and large hard drives are connected to motherboards personal computers by using serial interface SATA (Serial ATA). If you have very old computer, then a connection option using the parallel PATA (IDE) interface is possible. But keep in mind that the range of such hard drives in stores today is very scarce, since their production has almost completely ceased.
As for the SATA interface, there are 2 drive options on the market: connection via the SATA II or SATA III bus. In the first option, the maximum data transfer rate between the disk and RAM can be 300 MB/s (bus bandwidth up to 3 Gbit/s), and in the second - 600 MB/s (bus bandwidth up to 6 Gbit/s). It is also worth noting that the SATA III interface has slightly improved power management.
In practice, the bandwidth of the SATA II interface is enough for any classic hard drive. After all, even the most productive HDD models have a speed of reading data from the plates that barely exceeds 200 MB/s. Another thing is solid-state drives, where data is stored not on magnetic plates, but in flash memory, the reading speed from which is many times higher and can reach values of over 500 MB/s.
It should be noted that all versions of the SATA interface maintain compatibility with each other at the level of exchange protocols, connectors and cables. That is, a hard drive with a SATA III interface can be easily connected to the motherboard via a SATA I connector, although the maximum disk throughput will be limited to the capabilities of the older revision and will be 150 MB/s.
Buffer memory (Cache)
Buffer memory is fast intermediate memory (usually standard type RAM), which serves to level (smooth) the difference between the speeds of reading, writing and transferring via the data interface during disk operation. The hard drive cache can be used to store the last data read, but not yet transferred for processing, or data that may be requested again.
In the previous section, we already noted the difference between hard drive performance and throughput interface. It is this fact that determines the need for transit storage in modern hard drives. Thus, while data is being written or read from magnetic plates, the system can use the information stored in the cache for its needs without having to wait.
The size of the clipboard on modern hard drives made in the 2.5” form factor can be 8, 16, 32 or 64 MB. The older 3.5-inch brothers have a maximum buffer memory of 128 MB. In the mobile sector, the most common disks are 8 and 16 MB cache. Among desktop hard drives, the most common buffer sizes are 32 and 64 MB.
Purely theoretically, a larger cache should provide disks with greater performance. But in practice this is not always the case. There are various disk operations in which the clipboard has virtually no effect on the performance of the hard drive. For example, this can happen when reading data sequentially from the surface of the plates or when working with large files. In addition, the efficiency of the cache is affected by algorithms that can prevent errors when working with the buffer. And here a disk with a smaller cache, but advanced algorithms for its operation, may turn out to be more productive than a competitor that has larger buffer exchange.
Thus, there is no point in chasing the maximum amount of buffer memory. Moreover, if you need to significantly overpay for a large cache capacity. In addition, manufacturers themselves try to equip their products with the most effective cache size, based on the class and characteristics of certain disk models.
Other characteristics
Finally, let's take a quick look at some of the remaining characteristics you might see in hard drive descriptions.
Reliability or mean time between failures ( MTBF) - the average duration of operation of a hard drive before its first failure or the need for repair. Usually measured in hours. This parameter is very important for disks used in server stations or file storages, as well as as part of RAID arrays. As a rule, specialized magnetic drives have an average operating time of 800,000 to 1,000,000 hours (for example, RED series drives from WD or Constellation series from Seagate).
Noise level - noise created by the elements of the hard drive during its operation. Measured in decibels (dB). It mainly consists of noise that occurs when positioning the heads (crackling) and noise from spindle rotation (rustling). As a rule, the lower the spindle speed, the quieter the hard drive operates. A hard drive can be called quiet if its noise level is below 26 dB.
Power consumption - an important parameter for disks installed in mobile devices, where time is valued battery life. The heat dissipation of a hard drive also directly depends on energy consumption, which is also important for portable PCs. As a rule, the level of energy consumption is indicated by the manufacturer on the disk cover, but you should not blindly trust these figures. Very often they are far from reality, so if you really want to find out the power consumption of a particular drive model, it is better to search the Internet for the results of independent tests.
Random access time - the average time it takes to position the disk read head over an arbitrary area of the magnetic plate, measured in milliseconds. A very important parameter that affects the performance of the hard drive as a whole. The shorter the positioning time, the faster data will be written to or read from the disk. Can range from 2.5 ms (for some server drive models) to 14 ms. On average modern drives for personal computers this parameter ranges from 7 to 11 ms. Although there are also very fast models, for example, WD Velociraptor with an average random access time of 3.6 ms.
Conclusion
In conclusion, I would like to say a few words about the increasingly popular hybrid magnetic drives (SSHD). Devices of this type combine a regular hard drive (HDD) and solid state drive(SSD) small size, acting as additional cache memory. Thus, developers are trying to use together the main advantages of the two technologies - the large capacity of magnetic plates and the speed of flash memory. At the same time, the cost of hybrid drives is much lower than that of newfangled SSDs, and slightly higher than that of conventional HDDs.
Despite the promise of this technology, SSHD drives are currently very poorly represented on the hard drive market, with only a small number of models in the 2.5-inch form factor. Seagate is the most active in this segment, although competitors Western Digital(WD) and Toshiba have also already presented their hybrid solutions. All this leaves hope that the market SSHD hard drives will develop, and we will soon see new models of such devices on sale not only for mobile computers, but also for desktop PCs.
This concludes our review, where we examined all the main characteristics of computer hard drives. We hope that based on this material, you will be able to choose a hard drive for any purpose with the optimal parameters corresponding to them.
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