In our article, we will not once again discuss the topic of the transition from traditional magnetic platters to solid state drives. No, we will look at the transition from 3.5" form factor to 2.5" hard drives, as well as the spread of smaller hard drives in the corporate segment. Everything major manufacturers hard drives are offered today, according to at least, one line of 2.5" hard drives for the corporate market, and some have already announced the end of support for high-speed 3.5" hard drives at 15,000 rpm. SSDs provide more performance, while slower 3.5" hard drives offer capacities up to 2TB. Models in between seem to be moving to a 2.5" form factor, for reasons we'll try to figure out in this article.
The magic word in enterprise storage is "density", which usually refers to the available storage capacity in a given physical size. Density starts at the hard drive level, where it refers to the storage density per square inch of surface or platter. When you move to the system level, there is density per volume - how much information can you store in a 1U, 2U, 4U server, or even in an entire rack?
Storage density is correlated with the ability to increase storage performance, which also raises the question of moving from a 3.5" to a 2.5" form factor. Indeed, the performance of RAID arrays scales with the increase in the number of hard drives used, so it is obvious that more 2.5" hard drives will give a serious advantage compared to a small array of 3.5" HDDs. In the article we will look at performance, power consumption, capacities and some applications, for example, blade servers. Finally, the 2.5" form factor is the dominant form factor for SSDs, which paves the way for easy and convenient upgrades. But let's start with a discussion of flash technologies.
Flash everywhere?
In the coming years, solid state drives will appear in many client PCs and servers, as operating system and a set of applications especially large capacity not required. However, the current boom in SSD technology is associated either with the low-end segment, where capacity and performance are not so important, or with the high-end performance segment.
Let me briefly recap the potential benefits of flash memory technology.
Highest I/O performance: While enterprise-class hard drives can deliver a few hundred input/output operations per second (IOPS), decent SSDs can deliver thousands of IOPS. This is critical for many enterprise applications.
High throughput: HDDs today deliver a maximum of 200 MB/s, although SSDs easily exceed given level. Flash drives also offer a much higher and more consistent average throughput than HDDs.
Reduced maintenance costs: Since data is dynamically allocated to flash channels and cells by the controller, it is not necessary to defragment the SSD. Defragmentation can even degrade performance.
Energy Efficiency: HDDs require up to 20W of power, while SSDs typically consume very little power. a large number of energy is usually only a few watts. As a result, power efficiency in terms of bandwidth per watt or I/O performance per watt can be quite impressive.
Well-designed SSDs can deliver high bandwidth, better power efficiency, and I/O performance far superior to HDDs. However, mass-market hard drives, which are used in at least three-quarters of all systems and servers shipped, cannot be replaced by SSDs, despite the potential of SSDs.
Below we have summarized the list of existing problems.
Capacity: modern SSD for the corporate market they give from 32 to 256 GB, while enterprise-class HDDs have a capacity of up to 600 GB. And high-capacity storage can now be assembled from 2TB hard drives certified for the corporate segment.
Price: prices for SSDs for the enterprise market start roughly where prices for high-end hard drives for the same market end.
Validation A: Many HDDs are already validated for certain environments, while SSDs are (yet) not. This concerns compatibility and reliability, as well as performance predictability.
The result will be obvious: SSD technology can really provide benefits, but you have to start from scratch if you want the right implementation.
2.5" vs. 3.5" drive examples
First, I would like to remind you that 2.5" enterprise-class hard drives are taller than 2.5" hard drives for the consumer market. The latter are available in heights of 9.5mm (laptops) or 12.5mm (portable drives), but all enterprise HDDs are 15mm high. This is because they typically need to fit three physical platters. The same is true for 12.5 mm 2.5" hard drives, but increasing the spindle speed to 10,000 rpm or even up to 15,000 rpm imposes its own limitations. Yes, and it should be remembered that there are 2 platters inside, 5" and 3.5" enterprise-class hard drives actually have the same diameter, that is, the main advantage of a 3.5" hard drive compared to 2.5" is the ability to accommodate four or even more platters. As you can see, this applies to the maximum capacity, which, as we mentioned above, is not a priority for these enterprise-class hard drives.
3.5" Fujitsu MBA3147RC (15,000 rpm, 147 GB)
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To compare the performance of different form factors, we took HDD Fujitsu MBA3147RC. This drive is a good example of a 3.5" high performance enterprise hard drive. It is equipped with a 16 MB buffer, SAS interface at 3 Gbps and has a time between failures (MTBF) of 1.4 million hours. Toshiba, which bought Fujitsu last year, has no plans to release a 600GB 3.5" hard drive, ending the MBA line at 300GB. Other popular products are the Hitachi Ultrastar 15K and Seagate Cheetah 15K lines. It should be noted that other newer 3.5" 15,000 RPM hard drives offer much higher throughput, but I/O performance remains the same because read and write heads cannot be accelerated indefinitely. However, there are physical limitations. Faster 3.5" hard drives will deliver 150 to 200 MB/s.
Click on the picture to enlarge.
2.5" Toshiba MBF2600RC (10,025 rpm, 600 GB)
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This is one of the latest 2.5" enterprise hard drives. Toshiba's MBF line offers capacities up to 600 GB in a 2.5" form factor. This is one of the first hard SAS drives with a 6Gb/s interface that delivers twice the throughput of its predecessor. However, in reality this is not so important, since the performance of data transfer from the plates does not exceed 147 MB / s. The drive offers more bandwidth than our 3.5" Fujitsu hard drive comparison, but falls short of the latest 15,000 RPM hard drives. I/O performance is largely determined by spindle speed, which affects spin lag. products are available from Hitachi (C10K300) and Seagate (NS.2), but only Seagate and Toshiba currently ship 600GB models.
Click on the picture to enlarge.
2.5" vs. 3.5": performance and power consumption
It is quite important to compare the performance and power consumption of 2.5" and 3.5" drives. The Enterprise Performance Index above is based on our benchmarks, where throughput and I/O performance are weighted at 40%, and PCMark performance Vantage - 20 percent. You can skip to the benchmarks section to compare individual results, but the overall performance picture is pretty clear: the new generation of 600GB models in a 2.5" form factor with a 10,000 RPM spindle speed gives quite decent throughput up to about , 150 MB/s, but it can't beat 15,000 rpm 3.5" hard drives in I/O performance. However, a slight drop in performance is quite acceptable given the advantages of the 2.5" form factor over the 3.5" form factor, which we'll look at in a moment.
It is equally interesting to look at the power consumption in an I/O load scenario. workstation. While 15,000 RPM hard drives require anywhere from 7.8W idle to 12.4W with maximum I/O activity, the 600GB 2.5" Toshiba MBF2600RC hard drive cuts that power consumption in half. It consumes just 7.1 watts of I/O load, which is impressive, and only 3.5 watts when idle.
Finally, let's talk about efficiency. Power consumption is reduced much more than performance, so we can expect more performance per watt from 2.5" hard drives.
2.5" vs. 3.5": capacity and price
There are some other factors to consider before talking about capacity and density. As a rule, hard drive manufacturers try to create models with a reasonable number rotating plates. Single platter drives are most interesting for the consumer and customer markets where minimal costs are important.
Many platters are used to achieve higher capacities or to achieve the desired capacity on time-tested technology and recording density. However, fast 3.5" hard drives with big amount wafers are trying to combine high performance with high capacity, which is often accompanied by an increase in price. A 3.5" 7200 rpm hard drive delivers three times the capacity for about a third of the cost, and SSDs are taking over the performance segment.
There remains an average level of capacity - it is just given by products for the corporate mass market. This is where the 2.5" form factor really shines. Yes, you'll have to live with a slight drop in performance, but power consumption, efficiency and price are well balanced. Also, one product cycle is often enough to offset the performance drop. Existing recording densities allow the production of 2.5" hard drives at 10,000 rpm with 200 GB of capacity per platter. As a result, Seagate and Toshiba were able to introduce models with a capacity of 300, 450 and 600 GB. We expect Hitachi to follow shortly.
In terms of capacity
Considering that you can fit many more 2.5" hard drives in the same rack space than 3.5" drives, we get much higher storage density and power efficiency per gigabyte. Two 2.5" 300 GB 10,000 RPM enterprise hard drives in a proper RAID array will outperform a single 600 GB 3.5" 15,000 RPM hard drive. At the same time, the price and energy consumption will remain approximately comparable.
In terms of performance
If we look at the 3.5" vs. 3.5" scenario, multiple drives must be used to improve performance, capacity, or efficiency. In large corporate storage not only separate hard drives are used, but also HDDs combined into JBOD partitions. Let me give you a simple example.
The storage subsystem must provide a minimum of 1000 IOPS for file server and must have a capacity of at least 3 TB. The ideal option can be considered 1U storage with four 3.5" hard drives. If we take 600 GB hard drives at 15,000 rpm, then we will get the required performance, but we will not achieve the required capacity. A 2U system could increase the number of disks, but also the costs at This will also increase.An alternative is 1U storage, which can accommodate ten 2.5" hard drives. In our example, you can install six 2.5" 600 GB 10,000 RPM hard drives. In a RAID 5 array, they will provide the required capacity and performance at a lower total cost, lower power consumption, and much higher power efficiency compared to 3 .5" solution.
Finally, let's look at the price difference if you want to install an SSD. A single drive will likely provide the required performance, but we will need to use at least 24 SSDs of 128 GB each to get the desired capacity. In this case, we will not even provide storage redundancy, and the resulting solution will be massive. We will have to think RAID array, find suitable RAID controllers and fixtures to use 24 (or more) SSDs.
Let's talk about how many drives can work in a typical rack form factor server. The following figures are based on front-loading models. However, of course, there are rack servers that use . In addition, there are other options, such as two systems inside one blade package, adding or eliminating optical drive, more functional panel with I/O interfaces and so on. Thus, depending on the specific product, it may have fewer compartments than listed.
| rack server | 3.5" drive bays | 2.5" drive bays |
| 1U | 4 | 10 |
| 2U | 12 | 24 |
| 3U | 16 | - |
| 4U | 36 | - |
2U servers can accommodate 20 2.5" hard drives when installed horizontally, or 24 drives when installed vertically. In addition, 2.5" hard drive fixtures and bays require much less space than comparable 3.5" drives. solutions, because the drives are smaller in all three dimensions.
3U solutions usually support 16 3.5" hard drives. To be honest, we have not seen 3U or larger solutions that support even more 2.5" hard drives, since even a 2U server can install 24 drives.
Some special solutions allow you to fit a lot of computing power into a very limited space. good example it could be considered Supermicro SC809T-1200B, a 1U dual system that provides four 2.5" bays for each internal server. Since controls are required on the front panel, similar system cannot accommodate a maximum of ten 2.5" hard drives.
Blade servers
Click on the picture to enlarge.
The photo above shows a small 12U rack that holds three devices: a 4U system on the bottom, a 7U blade chassis with 10 modules in the middle, and a 2U server on top. As a rule, blade servers are installed in a 7U chassis, and up to 10 blade servers and various modules are allowed. While conventional rack servers include power supplies and network support, blade servers general nutrition and network. Of course, blade servers are the most efficient way to increase compute density in a server environment.
And here a serious advantage of 2.5" hard drives is manifested compared to 3.5" models: the latter simply will not fit in separate blade servers, that is, all blade servers must be equipped with 2.5" hard drives. This saves not only space, but also energy. Indeed, in a full chassis with 10 blade servers, you can install up to 60 2.5" hard drives. Multiply 60 by the Toshiba MBF2600RC's 7.1W consumption under heavy I/O load and you get a typical power consumption of 426W. On the contrary, the same number of 3.5" hard drives will require a chassis of at least 9U and 744W of power.
Many blade servers support three or six 2.5" hard drives (for dual blades), allowing you to set up an array with redundancy and decent performance.
Test configuration
| System hardware | |
| CPU | Intel Core i7-920 (45 nm, 2.66 GHz, 8 MB L2 cache) |
| Motherboard (Socket 1366) | Supermicro X8SAX, Revision: 1.1, Chipset: Intel X58 + ICH10R, BIOS: 1.0B |
| Memory | 3 GB DDR3-1333 Corsair CM3X1024-1333C9DHX |
| System HDD | Seagate NL35 400 GB, ST3400832NS, 7200 rpm, SATA/150, 8 MB cache |
| Power Supply | OCZ EliteXstream 800 W, OCZ800EXS-EU |
| Tests | |
| performance measurement | h2benchw 3.12 PC Mark Vantage 1.0 |
| I/O performance | IOMeter 2006.07.27 Fileserver Benchmark webserver-benchmark database-benchmark Workstation Benchmark Streaming Reads Streaming Writes |
| System software and drivers | |
| Operating system | Windows Vista Ultimate SP1 |
| Intel chipset drivers | INF Chipset Installation Utility 9.1.0.1007 |
| AMD Graphics Drivers | Catalyst 8.12 |
| Intel Matrix Storage Drivers | 8.7.0.1007 |
Data Transfer Diagrams
Remember that PCMark Vantage is not a server test. However, it is useful for identifying the difference between hard drives for different market segments. The test results are more dependent on throughput than I/O performance.
The surface temperatures of the drives are not very different, since a 3.5" hard drive is able to dissipate its heat over a much larger surface area.
Idle power consumption of 3.5W compared to 7.8W is a significant benefit.
Yes, even at peak load throughput 6.1 watts for a 2.5" drive is significantly better than 11.3 watts.
The power consumption of the 2.5" Toshiba MBF2600RC drive under a light limited load is very close to idle. The 3.5" Fujitsu MBA3147RC at 15,000 rpm under this load is closer to peak power consumption.
In an I/O load scenario, the difference in efficiency is not as significant, but the results for a 2.5" Toshiba hard drive almost double.
Conclusion
It would probably be too trite to say that 2.5" hard drives are better than 3.5" hard drives. The 2.5" form factor isn't great in every way, but you still need to consider the difference in storage density and spindle speed. In general, 3.5" 7200 rpm hard drives will remain very important for systems. high-capacity, and 2.5" high-performance hard drives will be widely used in servers in the coming years. SSDs are also becoming more and more interesting, but so far, this high performance or upgrading drives to 15,000 rpm.
Without a doubt, the high spindle speed and the most modern technologies provide very high throughput. But I/O performance is still limited by the physical performance of the read/write heads. Since they cannot be accelerated to infinity, they naturally limit I / O performance. The platter diameter of 3.5" and 2.5" hard drives for the corporate segment remains constant, so the I/O performance changes little. In our testing, Fujitsu's 3.5" 15,000 RPM hard drive was faster than Toshiba's 2.5" 10,000 RPM model solely because it has a higher spindle speed, which results in less spin lag. .
A couple of words about the interface: the choice of SAS 6 Gb / s or 3 Gb / s can be important for connecting fixtures and JBOD systems to the controller or host adapter, but for individual drives it does not matter.
In corporate environments, it's easy to see that you can typically fit twice as many 2.5" hard drives in a 3.5" rack space. Blade servers do not support 3.5" hard drives at all due to their physical size. Because the capacity and I/O performance are almost identical between 3.5" and 2.5" enterprise hard drives, but the power consumption and size of the 2.5 "There are much fewer models, as a result, we get a doubling of the efficiency and density of data storage when switching to 2.5" hard drives.
Anyway, the main difference hard drives with a form factor of 2.5 and 3.5, respectively, is the size itself, and only then technical features. The smaller form factor hard drive is only 15mm high, which is actually very convenient when building a compact but powerful server. Why exactly 2.5 and not 3.5 a little later!
In addition to the compact and attractive dimensions of hdd 2.5, which are used in every laptop, it is worth noting their wear resistance in terms of vibration and shaking, which cannot be said about the same 3.5. The latter assume exclusively stationary use. Someone will say that building a stable and voluminous system is possible only at 3.5, since due to the greater height of the case, up to 5 storage plates are installed inside. In the form factor 2.5 of those total 3. Such a statement has a right to exist, but it is worth paying attention to the scope of each of them.
So, for example, positioning in relation to a home PC is not advisable, since often the manufacturer simply installs the same storage platters from 2.5 inside the 3.5 hard drive, thereby bringing the natural transition of production to the 2.5 form factor. A potential consumer will not feel almost any difference.
A noticeable difference between the above HDDs, which can really be brought to the stage of a full-fledged comparison, is the principle of construction modern server and, as a result, obtain the total number of computational operations.
Form factor 2.5/3.5 and server height 43.7mm (1U)
The main difference in this case is the number of possible compartments. If, for example, we take a server with 3.5 slots as a starting point, then there are such bays total 4 pcs.
With a similar height of the 1U server, but the presence of slots for hdd 2.5, it is possible to install up to 8 drives. In this scenario, the total volume of the server can be doubled. Accordingly, the number of computational operations will also increase.
Even if we proceed from the principle of pricing for both types of drives, then the 2.5 form factor always retains the advantage of upgrading, installing SSD solid state drives. The potential industrial use of hdd 2.5 will significantly reduce the size of the server itself.
Above drives and server height 2U / 3U / 4U
A typical example would be the same 88.1 mm high (2U) industrial server. Subject to the availability of slots for 3.5 drives, a potential consumer will receive 12 expansion bays. If nevertheless we are talking about a server with compartments for a form factor of 2.5, then there are as many as 24 of them.
In the same way, you can calculate the number of bays of other servers, for example, 3U / 4U. With a height of 3U and bays for 3.5 drives, the owner is given the opportunity to install 16 pcs of drives, against a possible 32 pcs, in the case of bays for 2.5 drives. The latter is a more common option, since the number of compartments in the above sequence can reach 24 pieces and 48 pieces, respectively.
So the difference between hdd 2.5 and 3.5, in proportion to industrial server usage, is:
- The maximum amount of memory.
- The number of computational operations in relation to each drive (in the case of hdd 2.5, there will be 2 times more of them).
- Server dimensions and weight.
- Upgrade options for SSD (in the case of the 2.5 form factor).
- installation efficiency.
- Possibilities of building servers of modular and blade types; (all the same 2.5).
- Increase in input and output operations per second.
The most irrefutable advantage of hard drives 2.5 over 3.5, with the same server structure, is number of RAID groups the subsystem itself and their performance, which necessarily increases as more drives are connected. In this case, the advantage is on the side of smaller storage media and file systems. The number of installed ones is calculated based on the height of the server, which has already been discussed a little higher.
We tried to figure out what an SSD is and how it differs from classic hard drives. Concluding the general description, let's focus today on the form factor of drives. SSD Dimensions cannot be arbitrary, but subject to certain standards. Let's see what they are.
What is form factor
This is a set of requirements that must be met in the production of one or another computer component. The form factor is available for power supplies, motherboards, drives, cases designed to install motherboards of one form factor or another, etc.
This ensures that when installing a disk, motherboard or power supply into the case, all mounting holes, the location of interface connectors (for drives) will be the same for all devices, regardless of manufacturer, model, functionality. So, mATX form factor motherboards of any brand have the same dimensions and the location of the holes for screwing to the body.
The same is true for disks. 2.5 inch drives, no matter hard drives or SSD, have the same external dimensions, pin layout and mounting holes. The whole difference lies inside, in the filling.
There are several drive form factors currently in use, with SSDs offering a wider selection of sizes. This is due to the absence of moving parts and the theoretical possibility of performing freeform. Naturally, in order to be able practical application, this "shape" should be standardized.
Drives 2.5 inches
The size of small, laptop drives that has become familiar, rivaling traditional drives 3.5 inches. Most likely, there is no talk of active displacement of larger disks by compact analogues, but for SSD optimal Turned out to be 2.5 inches.
Externally, SDD differs from HDD only in weight (SSD is much lighter), and the absence of any visible printed circuit boards. This is a fairly simple, if not boring box. The connection is made to the SATA interface. Given the speed characteristics of SSDs, connecting to SATA below version 3 does not seem reasonable. In this case, the SSD will not reveal its potential.
I must say that here, in fact, ends the analogy with the usual hard drives. All other variations are the prerogative of SSD drives.
mSATA drives
A variety of conventional SATA, which is distinguished by its compact size, which is why the SSD itself lost its case, has become very small. This made it possible to use such capacious boards in compact computers, as well as install in laptops, in addition to the usual hard drive, another drive, in this case an SSD.
In particular, on the laptop on which I am now writing these lines, in addition to the usual hard drive, there is an SSD disk in the mSATA format, which I use as a system one. Even considering that I have a budget-class disk, the speed of work, system loading, and programs has increased significantly.
This form factor, for the mSATA connector, did not last long, giving way to a more promising option.
M.2 drives
Perhaps the most interesting option for SSD drives. The advantages are compactness, the ability to work not only on the SATA bus, but also on a significantly faster PCI-Express bus. This connector is now increasingly found in laptops and desktop motherboards.
If space is not an issue when building a regular PC, then in the case of a laptop computer, the ability to use a small, light, energy-efficient and fast drive is a blessing.
When choosing M.2 drives, there is a little confusion, which is based on the fact that the drive can work on different buses, i.e. use SATA or PCI-Express. Therefore, storage devices have different key, i.e. cutout on the connector.
As a rule, SSD drives are issued with keys:
- B key. SSD drives for SATA or PCI-Express x2 interfaces. In reality, this option is extremely rare.
- M key. SSD drives under PCI-Express interface x You can use drives with SATA interface which is emulated. A drive with such a key cannot be installed in a slot with a B-key operating on the SATA bus.
- M&B (M+B) key. Universal option for SSD drives running on the SATA bus. Can be installed in sockets with both B-key and M-key.
The form factor for SSD M.2 is also regulated in length and width. Typical SSD drive sizes are 22mm wide and 16mm to 110mm long. A complete list of allowable dimensions in length: 16, 26, 30, 38, 42, 60, 80, 110 mm. The most common are 42, 60 and 80 mm.
This is reflected in the labeling of SSD drives. So, if it is indicated that the disk is M.2 2242, then this means that the dimensions of the drive are 22x42 mm. If M.2 2280, then, respectively, 22x80 mm. Everything is simple!
Even if the motherboard does not have an M.2 connector installed, you can still use such drives. Many manufacturers offer drive models with a PCI-Express adapter card. Accordingly, the SSD drive itself is also designed to work with this bus. The "rate of fire" of such a disk will be very impressive. After it, the performance of a conventional hard drive will be perceived as depressing.
Unfortunately, there is a small fly in the ointment in all these "goodies". The compact size of SSDs limits storage capacity. This is due to the number of memory chips that can be placed on such small board. Maximum M.2 SSD capacity per this moment does not exceed 1 TB. Increasing this value will allow more capacious memory chips, which will undoubtedly appear.
PCIe Add-in Cards (AICs)
These are drives made in the form of an inserted into PCI-Express slot cards that can be standard or half size in both length and width, which allows them to be used in 2U rackmount cases. Actually, such SSDs belong to the corporate class and are intended primarily for installation in servers and storage systems (Data Storage Systems).
The drives use, as a rule, SLC memory, which is expensive in itself, but reliable and durable. Use such discs in a normal home computer is a luxury that not everyone can afford. True, and there is no particular need for this.
SATA-Express drives
Finding such discs is almost impossible. This interface was planned to replace the good old SATA with its leisurely 600 MB / s maximum throughput. It was painfully tempting to use a faster PCI-Express bus. So this interface was planned, using 2 PCI-Express lanes, which would allow reaching a maximum throughput of 2 GB / s.
Apparently, this interface will remain one of the stages that have not found implementation, because even now M.2 SSDs can use 4 PCI-Express lanes with a peak bandwidth of 4 GB / s. A special cable is used for connection.
U.2 drives
There are also SSD drives. This form factor allows you to use all the advantages of a high-speed PCI-Express bus, but is not limited to drives with an M.2 connector. Outwardly, they resemble 2.5-inch drives, but with a thickness of up to 15 mm. 4 PCI-Express lanes are used.
The choice of such disks is very small, and they are mainly oriented for use in servers, storage systems (data storage systems), data centers, etc. If, on the other hand, motherboard there is an M.2 connector on the PCI-Express bus, and there is a U.2 form factor SSD, then it will still be possible to connect it. There are M.2 to U.2 adapters, which will allow you to feel the full power of such a high-speed drive.
At the moment, this form factor is rather a matter of the future, and first of all it is relevant for servers.
Drives for installation in the DIMM slot
If we talk about the exotic, then there are such sizes of SSDs that they are completely identical, coincide with the sizes of conventional memory modules, and are installed in a free RAM slot. This may be relevant for specific server platforms with a large number of DIMM slots.
Exist different variants, combined on the same SSD and RAM module, or only solid state drive plugged into the socket for random access memory, which receives power from it, but data is transmitted using a regular SATA cable connected to the module and the motherboard or controller.
For home computers, this is of little interest, and it is difficult to find them on sale.
SSD dimensions. Conclusion
So, to briefly summarize, the size of SSD drives, that is, the form factor, determines the physical dimensions of the drive, which also affects its characteristics. A 2.5-inch laptop hard drive can be easily replaced with the same SSD. It will suit both the location of the mounting holes and the connectors - power and interface.
If your computer has an M.2 connector that supports, for example, 2242, 2260, and 2280 drives, then you can also install a suitable SSD. The main thing is not to make a mistake about which bus this interface uses and, accordingly, which key is in the connector. The M+B SATA SSD can be used in any computer with an M.2 connector. If the SSD uses a PCI-Express bus, then it has an M-key, and can only be used in an M.2 slot that works on this bus (also with an M key).
At the moment, these are the 2 most common form factors of SSD drives. The choice in favor of one or another option is determined by layout considerations, necessity, cost and a number of other reasons.
This is where we will finish with the size of SSD drives, and in the next article we will get into the insides. We will deal with the ones that are used in these drives, what they are, how they differ, what are the advantages and disadvantages.
As for the specification, it consists of additional components.
Only a large number of manufacturers support a certain specification, because all characteristics will directly depend on the compatibility, and other standardized equipment package, such as expansion cards.
Some manufacturers prescribe the abbreviations SFF and LFF, which replace the inch designation. This characterizes the form factor 3.5″, correspondingly worthy of its parameters.
computer accessory
Everything computer companies use such a thing as "form factor" in order to describe any of the components of the device, for example, a hard drive.
As a hard disk, specialists in the design used a magnetic plate, which had a diameter of about 8 inches.
It occupied a fairly large size on the hard drive, therefore, it determined the dimension of the entire metal case, which in turn protected all internal accessories.
The height of the hull itself depended on the number of “layers”, which was typical for each model separately. The largest was made up of 14 of these. Therefore, from that time on, it was possible to determine the required dimensions for a hard drive by the diameter of the magnetic plate.
After the usual 8-inch drives, they appeared with a size of 5.25, which could be attributed to the main component of a stationary PC.
SSD Form Factor Parameters
The whole problem lies in the fact that because of his large sizes increases the cost of the finished device. Indeed, for the multifunctional operation of the SATA connector, you will need to solder it firmly to the board.
positive moment was the creation of drives that are an interface - this is the extreme location of the board, similar to the expansion board.
To connect this type of connector, you will need to include it in a specific slot without other connectors and wires.
In connection with the need for disk mineralization, JEDEC designed the MO-300 model, which had dimensions of 50.8x29.85 mm, and also had a mini-SATA connector. This connector model is the same size as mini PCI Express, only electrically they are not compatible. A large number of solutions have been presented for this form factor. For example, to produce drives with increased capacity, there is a form of sublines to mount several chips in memory.
NGFF disk
At the beginning of 2012, a new device was released, with an impressively reduced size - NGFF (later renamed to M.2).
This standard has the definition of many different board sizes, leads to the input of a connector that is electrically compatible with PCIe and mSATA.
By its shape, certain details of the interface can be determined.
When designing laptops, Apple often used a proprietary interface that is identical to M.2.
He changed his parameters every year. To achieve more high speed, specialists in 2013 switched to the PCIe interface.
There are times when a large number of standard form factors do not fit at all, in which case manufacturers design highly specialized solutions to such an issue that work at a niche level.
Well, now let's take a closer look at the familiar version of the interface - this.
Important! The number of platters that can be placed in a 2.5 form factor disk is exactly 3 pieces with a height of 15mm, and for HDD 3.5 - no more than 5 platters.
We pay a lot of attention hard drives. This is one of those components of the system, on which the comfort of working with a PC largely depends. And if earlier we mainly considered the capabilities of 3.5-inch drives, now hard drives with a platter diameter of 2.5″ are of no less interest - such HDDs are used not only in mobile devices, but also in monoblocks, nettops and other compact economical PCs. Having the same principle of operation, the drives of these two form factors differ markedly technical specifications. How exactly? Let's figure it out.
Physical Dimensions
The first thing you notice when looking at drives of two form factors is the difference in their dimensions. 2.5" drives are much smaller than their 3.5" platter counterparts.
The amount of space occupied standard HDD, almost six times more than in the case of a mobile hard drive with a thickness of 9.5 mm. Moreover, if we calculate the capacity of stored information per unit of volume, taking as a basis a 750-gigabyte portable disk and a 2 TB desktop drive, the difference will be more than twofold, and not in favor of the latter (11.3 GB / cm3 and 5.1 GB / cm3).
Recording Density
The diameter of magnetic disks of drives of both types differs by 40%, while the plates of 3.5-inch hard drives have 1.8 times the working area. The same ratio is maintained if we consider the maximum capacity of the disks used in the HDD - for portable drives it is 375 GB, for desktop - 667 GB. From a technological point of view, the surface recording density on magnetic platters for both form factors is approximately the same. If we take into account only the formatted area available for writing user data, then for the most capacious platters this is about 330 GB per sq. inch.
| Dimensions Compact size is one of the main advantages of 2.5-inch drives. Despite the fact that the diameter of their plates is only 1.4 times smaller, they take up much less space in the system case. With standardized length and width, disks differ in thickness: ultra-thin - 7 mm, the most popular models with two platters - 9.5 mm, capacious three-disk - 12.5 mm, hard drives for server solutions - 15 mm. | Dimensions Here, 3.5-inch drives have nothing to cover: the dimensions of their case are much larger than those of portable models. However, for home desktop PCs, this is not so important; desktop cases always have a basket for several hard drives of this type. Well, for compact systems The choice of hard drive form factor is obvious. |
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| Volume The current maximum capacity is 1 TB. In addition, such HDDs consist of three magnetic platters and have a thickness of 12.5 mm instead of the typical for most modern models 9.5 mm. Dual platter drives are currently limited to 750 GB. If we do not talk about an array of several drives, then they are not very suitable for creating a capacious data warehouse. | Volume The relatively large dimensions of the drive allow manufacturers to install four or even five magnetic platters if necessary. Considering that each of them is already capable of storing up to 670 GB, the total capacity of a 3.5″ drive can exceed 3 TB. At this moment popular models HDDs are equipped with 333–500 GB platters with a total capacity of 1.5–2 TB. |
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| Performance The issue of performance is not as straightforward as it might seem at first glance. On the one hand, mobile drives are somewhat slower than desktop HDDs. On the other hand, the most productive hard drives for PCs - WD VelociRaprot - use exactly 2.5-inch magnetic platters. Therefore, the nuances are important here. If we still talk about the usual hard drives with a case thickness of 9.5 mm, two platters of 320 GB each and a spindle speed of 5400 rpm, then in fact they are no longer inferior in terms of speed to economical models of 3.5-inch HDDs. Medium line speed read / write - 65-70 MB / s with a peak at the beginning of the disk ~ 90 MB / s. | Performance Typical models with a spindle speed of 7200 rpm outperform mass-produced 2.5″ devices without problems in both line transfers and access speed. However, the difference in performance is not so great. With equal recording density on the plates and the speed of their rotation, compact drives are practically not inferior to large HDDs. |
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| power usage 2.5-inch HDDs are quite economical. Typical power consumption for dual-drive models is 2-4W in read/write mode. Yes, it is for this reason that after the replacement in laptop hard a disk on an SSD fails to get a noticeable increase in autonomy - these hard drives consume not much more than solid-state drives. | power usage Drives with 7200 rpm during active operation consume on average about 8–12 W, low-speed models - 6–8 W. That is, it is noticeably larger than hard drives with a platter diameter of 2.5″. For desktop PCs using 3.5" HDDs, hard drives magnetic disks- far from the main consumers of electricity, because 3-5 W do not play here important role. But if you want to create a truly economical system, you should take a closer look at portable models. |
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| Noise and heat As a rule, 2.5-inch drives make less noise - the sound from the spindle is noticeably muffled, and the chatter of moving heads during active search is also barely audible. As for heating, a lot depends on the operating conditions and the cooling system, but in general, no one has canceled the law of conservation of energy: less energy consumption - less heating. | Noise and heat Hard drive noise actual question for desktop owners. The sound of the 3.5″ hard drive engine is heard only on an open stand, but the crunching when moving the heads can be quite noticeable, although much here depends on the rigidity of the chassis chassis and the presence of damping pads. Temperature affects HDD heating level environment, number of magnetic plates and spindle speed. Operating mode - 40–50 ˚С. |
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| Price The cost of information storage portable models still inferior to 3.5-inch, but over the past couple of years the difference has decreased significantly. For example, a popular 500 GB compact disk costs only $15–20 more than an HDD of the same size with 3.5″ platters. | Price In the past few years, along with the increase in volumes, the cost of storing data on 3.5-inch hard drives decreases regularly. So, $0.065 per 1 GB is a record figure, thanks to which these hard drives will remain an actual type of data storage device for a long time to come. |
