Explaining SSDs: Form Factors, Interfaces & Technologies

[Music] welcome to another video from explaining computers this time i'm going to talk about these things solid-state drives or ssds specifically i'm going to explain all of the different ssd form factors interfaces and technologies so let's go and get started for many years almost all computers stored their operating systems programs and data on hard drives with three and a half inch models being most common in desktop pcs whilst two and a half inch drives were found in most laptops however today an increasing proportion of computers use an ssd instead of or addition to a hard drive ssds stored data on solid-state flash memory chips which makes them faster more power efficient and more robust this said the cost of storing data on an ssd is still greater per gigabyte than using a hard drive today ssds come in many different sizes or form factors with the most common being two and a half inch and m.2 as we can see two and a half inch ssds are the same size as two and a half inch hard drives and they connect to a computer using a cable which plugs into a connector on the end of the drive and then the drive then mounts with screws meanwhile m.2 drives usually stock directly into a computer's motherboard and come in a variety of sizes which are expressed as a code for example this is a 2280 m.2 ssd which means this is 22 millimeters wide and 80 millimeters in length and this is a 2260 m.2 ssd which is therefore 22 millimeters wide and 60 millimeters long other possible dimensions for m.2 devices are 1630 2230 3030 2242 3042 and 2210 although not all of these are used for m.2 ssds when purchasing an m.2 ssd it is of course critical to get one which will fit your motherboard although it's worth noting that many motherboard slots can accommodate several m.2 sizes while two and a half inch m.2 ssds are the most common other form factors are available not least there are a few three and a half inch ssds such as the nimbus extra drive dc 100 with a 100 terabyte capacity this is currently the highest capacity ssd on the market and is a very high-end enterprise device with a forty thousand dollar price tag to match also at the higher end of the market we find aic or add-in card ssds that plug directly into a pcie slot on a computer's motherboard these also come in different sizes and most usually hhh l which stands for half height half length or fhhl which stands for full height half length examples include the samsung pm1733 and the wd black an1500 note that there are also pcie add-in card adapters that allow one or more m.2 ssds to be plugged into a standard pcie slot a final fairly common if older ssd form factor is msata this was defined in 2011 before m.2 was specified in 2013 and can still be found in many laptops and other mobile devices however this all said today if you are purchasing a new ssd it is most likely you'll be selecting a two and a half inch form factor drive or an m.2 drive ssds are available with a variety of different interfaces with the two most common being sata and pcie mvme sata stands for serial advanced technology attachment and delivers a maximum data transfer speed of around 550 megabytes a second meanwhile pcie stands for peripheral component interconnect express with nvme or non-volatile memory express being a standard for connecting ssds via pcie you may see ssds labeled as having a pcie interface an nvme interface or a pcie nvme interface but today all of these refer to the same thing maximum data transfer speeds for nvme ssds or up to 7000 megabytes a second for the latest drives connected to computers with a pcie 4.0 interface now it is very important to appreciate that an ssd's form factor does not determine its interface very frequently i read comments here on youtube that say things like m.2 ssds are better than two and a half inch ssds because m.2 drives are faster and this is not always true for start m.2 ssds can have either a sata or an nvme interface so for example here this western digital m.2 drive is an nvme drive but this transcend drive is a sata drive and so operates at the same speed as most two and a half inch drives which have a satter interface this said there are two and a half inch drives that have a pcie nvme interface known in this context as u.2 the connectors on sata and udot two two and a half inch ssds do look fairly similar but they are not identical as this graphic shows examples of two and a half inch ssds with the u.2 pcie nvme interface include the kingston dc1000m and the wd gold enterprise class nvme ssd it's also worth noting that some two and a half inch enterprise ssds come with a serial attached scussy or sas interface that can provide data transfer speeds of up to 1200 megabytes a second or twice that of saturn now because ssds with the same form factor can have different interfaces it becomes very important to purchase the right drive for your system if you want it to fit and work properly when purchasing a two and a half inch ssd you should have no problems in practice as all consumer drives have a saturn interface with u.2 and sas connectors being rare on most motherboards you're therefore very unlikely to purchase a u.2 or sas two and a half inch ssd by accident the same however is unfortunately not the case when it comes to m.2 drives with many reported instances of people purchasing an nvme m.2 ssd where it needs a nasa one and vice versa so it's incredibly important to check just which kind of m.2 ssd your system supports today most new motherboards have slots that work with both sata and nvme m.2 drives but there is still a lot of older desktop motherboards and laptops out there but are sata or nvme only nvme and sata m.2 drives do look identical and i'd note that the different lengths of these drives has nothing to do with their different interface it's also important to note that all m.2 devices have slots or keys to prevent them being fitted into the wrong kind of m.2 slot specifically m.2 ssds can be either b keys m keys or both here like all modern nvme drives this wd black is m keyed whilst like most sata drives this transcend is both b and m keyed finally just to make sure everything is as clear as possible let's finish this segment with a table indicating the different interfaces available in different ssd form factors as we can see 2.5 inch ssds can have a sata u.2 nvme or sas interface while m.2 drives can be sata or mvm e meanwhile pcie add-in card ssds are only ever pcie mvme whilst msata or mini satur ssds are only ever satter as their name suggests most ssds store data in their flash memory chips using nand logic gates two technologies are commonly used called floating gate and charge trap flash in both of these to write or program data a voltage is applied to move electrons into a floating gate or charge trap layer the presence of these electrons changes the resistance between the membrane cell's source and drain electrodes and this can be measured by passing a current between them so allowing data to be read from the cell to erase the cell a voltage or field is applied to remove the electrons from a floating gate or charge trap layer however repeated program arrays operations weaken the material the cell is made from which results in electrons either escaping a floating gate or being retained in the charge trap layer after a certain number of program arrays or pe cycles it therefore becomes impossible for the cell to reliably function the practical implication is that all ssds can only sustain a limited number of data right operations before they fail the technology in the first ssds was called single level cell or slc and stored just one bit of data per memory cell the cell was therefore only required to maintain two possible states of fully programmed or fully erased however today most ssds store multiple bits of data per memory cell in order to increase drive capacity at a reduced cost inevitably this reduces the number of program arrays cycles and ssd can reliably sustain and also makes the drive operate more slowly therefore when you purchase an ssd you may wish to consider how many bits of data it stores per memory sell as this will determine its speed and life expectancy after slc ssds came multi-level cell or mlc drives that store two bits of data per memory cell so requiring the cell to reliably distinguish four programmed states next came triple level cell or tlc ssds followed by quad level cell or qlc today manufacturers including intel and toshiba are working on pentalevel cell or plc-ssds although these are yet to arrive on the market the programmer raised life expectancy for any individual ssd varies significantly but as a guide slc drives can sustain up to about one hundred thousand programmer race cycles mlc about 3 000 for consumer drives tlc somewhere between 500 and 2000 and qlc between 300 and 1000 whilst these numbers may seem very low it should be remembered that most users only write or rewrite data to a very small percentage of their drive on a daily basis and so even qlc and future plc drives will work reliably for many years for the vast majority of the users having just explained slc mlc tlc qlc and plc i thought it was important to finish off by saying a few words about how samsung chooses to label its drives and its technical specs because it can make matters slightly confusing and this is because samsung labels every drive it has as being mlc and that indicates the total number of bits stored the cell so for example here is a samsung pro drive which is mlc which samsung labels as 2-bit mlc that's not too confusing but over here we have a samsung cuvo drive which is qlc but samsung labels this as four bit mlc four bit multi-level cell which i suppose is technically correct if you just use multi-level cell to mean multi any number when you define a number of bits stored alongside it but in the world where we've generally taken mlc to mean two bits per cell that can confuse matters a bit so here's a little table just to explain what samsung does with mlc being two 2-bit mlc tlc being 3-bit mlc qlc being 4-bit mlc and presumably in time plc will be labeled on samsung drives as 5-bit mlc over the past decade ssds have helped to make laptops lighter more robust and to have an improved battery life as well as allowing computers of all kinds to boot more quickly and to benefit more generally from faster storage technology if you want to know more about different types of computer hardware you may want to check out some of the other videos on this channel including explaining ram and explaining pcie slots but now that's it for another video if you've enjoyed what you've seen here please press that like button if you haven't subscribed please subscribe and i hope to talk to you again very soon you

Channel: ExplainingComputers

Views: 273,666

Keywords: SSD, M.2 SSD, 2.5 inch SSD, 2.5 SSD, SATA SSD, NVMe, PCIe NVMe, PCIe SSD, NVMe SSD, u.2, U.2 SSD, SAS SSD, 3.5 SSD, AIC SSD, SSS add in card, SLC, MLC, TLC, QLC PLC, penta level cell, Christopher Barnatt, Barnatt, M.2 keys

Id: EXLfErPEYiw

Length: 14min 19sec (859 seconds)

Published: Sun Nov 15 2020

Reddit Comments

[u/VorlonHelper]

Has anyone had to back up data from an m.2 in a pc that won't boot yet? Is there a way to get a reader through official channels or should I get the gm to approve petty cashing one from newegg or amazon?