Explaining SD Cards: 2020 Update

[Music] welcome to another video from explaining computers comm this time I'm going to talk about secure digital or SD cards these were first launched back in 1999 and are now available with many different capacity types speed classes and bus interfaces new SD card standards have also been announced and so in this video I'm going to explain all current of forthcoming SD card specifications as well as running some performance tests 20 years ago the first SD card were what we now call standard size smaller mini SD cards and arrived in 2003 followed by even smaller micro SD cards in 2005 today mini SD cards are rare with most devices using either a standard or a micro SD card and newer SD card specifications not supporting mini SD all SD card form factors are available in a range of capacity types the first of these is SD which supports cards up to 2 gigabytes in size next comes SDHC or secure digital high capacity for cards over 2 gigabytes and up to 32 GU bytes after that we have SD XC or secure digital extended capacity cards with a size over 32 gigabytes up to 2 terabytes in June 2018 the SD card Association also announced a fourth capacity type called SD UC or secure digital ultra capacity this will support cards over 2 terabytes and up to 128 terabytes potentially offering a mind-blowing quantity of storage in something the size of a fingernail most SD cards are labeled with up to three different types of speed class all of which indicate the minimum sequential write speed but a card is capable of the initial SD card speed classes were class 2 class 4 class 6 or class 10 with a number appearing the letter C and the classes indicating a minimum write speed of 2 4 6 or 10 megabytes a second next we introduced was the UHS or ultra high speed speed class which indicates if a card can sustain either a 10 or 30 megabytes per second sequential write speed by placing at number 1 or 3 inside a letter you most recently SD cards have started to be labeled with a video speed class with a figure 6 10 30 60 or 90 appearing after a letter V as we can see the video speed class can indicate a minimum sustained write speed of 6 10 30 60 or 90 megabytes per second it's also worth noting the manufacturers often label their card with a claimed speed here for example a 2 SanDisk Extreme Pro cards with labeled speeds of 95 and 170 megabytes per second but both cards are only classified as u3 and V 30 indicating a minimum write speed of 30 megabytes per second it is in fact only when we look to the box with a 64 gigabyte card that we can see it claim speed of 95 megabytes a second is a potential up to or maximum speed and we have to turn the box over to discover that 95 megabytes a second is the potential read rather than write maximum you may also have noticed that this box labels the card as 6 3 3 times such multiplication rates are not part of the official SD card Association specifications but are often cited by manufacturers what they indicate is how the potential speed of a card compares to a standard speed or x one cd-rom drive which can transfer data at about nought point one five megabytes per second so here the six three three times figure means that the card may operate 633 times faster than the slowest cd-rom drives finally it's worth noting that some SD cards are labeled with a fourth application performance class which can either be class 1 which is denoted as a 1 or class 2 which is denoted as a 2 here the minimum sustained write speed is 10 megabytes per second just as it is for a class 10 u 1 or V 10 card however a1 and a2 cards are also certified for a minimum number of ions or input/output operations per second hi I ops and values are important with an SD card ease use as a computer or smart phones operating system or application drive which is increasingly common today SD cards and devices are available with several different bus interface standards these relate to the speed of electronics used to transfer data and aural interface hardware specification which is quite distinct from less d cards speed class at least in theory right now there were four different SD card bus interface standards known as high-speed uhs-1 UHS 2 and UHS 3 these offer potential maximum data transfer speeds of up to 25 104 312 and 6 to 4 megabytes per second normally all you see indicated on a card is a single Roman numeral with most modern SD cards being labeled 1 or 2 to indicate they have e3 uhs-1 or UHS 2 thus interface note that here UHS again stands for ultra high-speed but that an SD cards bus interface specification is entirely distinct from each UHS speed class SD cards with either a high speed or uhs-1 bus interface communicate data over one row of pins however to achieve higher data transfer speeds UHS 2 and UHS 3 cards require a second row of connectors this means that it's very easy to distinguish card with a slower or faster bus interface just by turning them over in practice today if an SD card has two rows of pins it has a UHS - bus interface although the faster UHS 3 standard which uses the same pin out was announced in February 2017 UHS 3 cards and devices these are not made it to market or are exceedingly rare and in hiding UHS 3 is now also very unlikely to go mainstream as in June 2018 a new standard was announced called SD Express this again will have 2 rows of pins with the upper one maintaining a UHS one interface for backwards compatibility and the lower row of pins offering a PCIe gen3 bus interface with nvme protocols the latter promises a maximum data transfer speed of nine hundred and eighty-five megabytes per second SD Express SD cards will therefore be able to be used in the place of regular SSDs with potentially major implications for the size and design of many different categories of computer and IOT device already many single board computers store their operating system on an SD card and this may be increasingly common in the future today like many people I do most of my video work using UHS 1 SD cards with my go-to cards being the 64 or 128 gigabyte SanDisk Extreme Pro models however for this video I thought I'd test out the UHS 2 version of a 64 gigabyte card to experience the performance improvement and if we now exchange out this a 128 gigabyte UHS one card for this a new 64 gigabyte UHS 2 card and we then just flip these over you can see we've got the one row of pins on the OHS one card and the two rows of pins on the OHS to card which allows it to operate faster but it's important to stress that this card lonely operate at higher speeds if it's using a device that also got a UHS 2 interface and which can make use of the second row of pins and in this context I know that my Blackmagic Design video assist 4k that I use for HDMI recording has got a UHS 2 interface and to test out the card in a PC and to run some speed tests I've also purchased this a SanDisk Extreme Pro UHS 2 card reader so I'm going to just open this thing up there we are and putting a card and assess summer relative uhs-1 and UHS 2 performance so here we are in Windows on my laptop I've currently got new HS one card plugged in and as you can see I've run up crystal dis mark and we've got selected there uhs-1 card D Drive here as the tester device so let's run all the tests and there we are and the headlines here are the read and write figures for very large files which are clearly what matter if we're actually using cars for for video work and as we can see ninety three point five megabytes a second read and a seventy six point five megabytes a second right so let's use the magic of filmmaking to put those onto one side of the screen and repeat this test for the UHS two card and there we are and as we can see the headline here is we've got almost twice the performance in terms of the read speed and almost two and a half times performance or something like that in terms of right speed so clearly we have got significantly better performance with the UHS to card which will allow for example certain video recording devices to record video with a much higher data rate now a second test I want to run is copying data from each of these cards back to an SSD on a PC because that's a very real-world test and so what I've got set up here is well each of the cards one file which has been recorded on the Blackmagic Design video assist 4k a standard video file about four half gigabytes in size so by the magic of filmmaking I'm going to start off the paste on both of these at the same point in time and we'll see how fast they go we can see clearly straight away the UHS to card is going to win answers to my question over how much butter will speed on through to the interesting bits and there we are VHS to card has finished in twenty-one point seven seconds at about two hundred fifteen point five megabytes a second but not to be outdone we then get with UHS one card finishing in fifty four point three seconds which is a eighty six point one megabytes a second but the one thing I haven't mentioned so far is the relative price of these two cards and in late February twenty 20 new HS one sixty-four gigabyte card cost $17 ninety-nine or 17 pounds forty nine whilst the hs2 card cost $92 80 or 87 pounds ninety-nine whether the extra cost is worth it will of course depend on your use scenario but I suspect that for quite some time few people will be prepared to pay for SD card interfaces faster than UHS one SD cards have evolved very significantly over the past 20 years and with their speed and capacity set to further increase this should be around for a decade or more in a forthcoming video I'm going to be testing out all of these micro SD cards to see which one works best as a boot drive in a single board computer but now that's it for another video if you enjoyed you seen her please press that like button if you haven't subscribed please subscribe and I hope to talk to you again very soon [Music] you

Channel: ExplainingComputers

Views: 375,337

Keywords: SD Express, SD cards explained, SD card formats, SD card types, choosing SD card, SDUC, SDXC, SDHC, Mini SD, SD capacity types, SD bus interface, SD interface, UHS-I, UHS-2, UHS-3, NVMe SD card, Christopher Barnatt, Barnatt, UHS-I vs UHS-II, SD card speed test, SanDisk Extreme PRO, SD application class

Id: oLQ8A_vcBqU

Length: 13min 25sec (805 seconds)

Published: Sun Mar 01 2020