QLC vs TLC SSDs: Samsung QVO & EVO

[Music] welcome to another video from explaining computers comm this time I'm going to talk about with differences between qlc and TLC SSDs ql c stands for quad levels cell and it's a relatively new to market technology which allows SSD manufacturers to produce higher capacity drives at lower cost however qrc does have some disadvantages compared to TLC or triple level cell drives and as their further to talk about the drawbacks after that i'm going to do some practical testing i'm going to compare the performance of this samsung couvreux on terabyte SSD with this Samsung Evo won't terabyte SSD as these are based respectively on qlc and TLC technology to appreciate the differences between qlc and TLC it's important to understand the basic operation with SSDs NAND flash memory cells 2 technologies are commonly used called floating gate and charge trap flash in both of these to write or program data of voltages applied to move electrons into a floating gate or charge trap layer the presence of these electrons changes the resistance between the memory cells source and drain electrodes and this can be measured by passing a current between them so allowing a data value to be read from the cell to erase a cell or voltage is applied to remove the electrons from the floating gate or charge trap layer however repeated program arrays operations weaken the material a cell is made from which results in electrons either escaping a floating gate or being retained in a charged trap layer after a certain number of program arrays or p/e cycles it therefore becomes impossible for the cell to reliably function so how does this relate to cure see and TLC SSDs well the first solid-state drives where SLC or single-level cell and used each memory cell to store just one bit of data the cell was therefore only required to maintain the two possible states of fully programmed or fully erased next came multi-level cell or mlc SSDs which increased capacity by storing two bits of data in each cell so requiring cells to reliably distinguish for programs states as you can probably guess triple level cell or TLC SSDs store three bits of data per memory cell and hence have to distinguish eight cells States and quad level cell or qlc drives store four bits of data per cell so much reliably distinguish sixteen program erase levels the more states in memory cell has to distinguish well as tolerant it becomes of electron leakage or retention and the more work that write us to perform when storing data as a result as the number of bits stored per cell increases the fewer PA cycles an SD can endure before failure and was slower its sustained write speed the exact number of program erase cycles varies but is up to about 100,000 for SLC up to about 3000 for consumer mlc between about 500 and 2,000 for TLC and between about 300 and 1000 for current qlc SSDs this may lead you to conclude that you should never buy a qlc SSD however the practical implications depend on how weather dry performs in actual use so let's now compare Samsung's latest qlc and TLC consumer SSDs so here we have our two Samsung 860 SSDs which are both want terabyte two and a half inch drives but the qo Drive over here is a ql c drive which in august 20 1934 116 pounds whilst the evo drive over here this is a TLC drive which is currently listed at 170 dollars or 153 pounds so based on the official Samsung prices the Q vasya ql c drive lives up to the promise of a 25% lower cost per gigabyte so what are the practical differences well if we turn these over ever look on the back we can see that the TLC evo drive bears the strap line the SSD that makes a difference and has a five-year limited warranty whereas the qlc Cubo drive is labeled as a quality and value optimized SSD and has a three year warranty delving deeper into the specifications by the Samsung website the evos warranty is actually five years or 600 tbw or terabytes written whereas the Hugo warranty is three years or 360 terabytes written so what Samsung is saying is that it expects a one terabyte Evo to have an endurance of at least 600 P cycles whilst the guaranteed endurance the one terabyte couvreux is 360 P sy khals to put this further in context the warranty on a Samsung pro one terabyte SSD something like this which is a mlc drive to bits stored per cell this has a five year warranty and twelve hundred terabytes written so effectively with each extra bit of data stored per memory cell Samsung is roughly carving the data written life expectancy so let's bring in Stanley of a knife and open up these rather exciting boxes and there we are we have our two lovely different ways around there we are our lovely to newer SSDs just before we test these out it's worth mentioning that Samsung uses a technology called intelligent turbo right to improve the write performance of its a qlc and the TLC SSDs and this uses some memory cells as an SLC cache to which data can be written very quickly before it's moved to a ql c or TLC cells when the drives not receiving data and by default owner want terabyte drives like these the SLC turbo write cache is 6 gigabytes but it can increase to 42 gigabytes and so this means that continuously writing up to forty two gigabytes of data to these drives should be very fast but once we've hit the fortitude gigabyte cache level we can't write any more data continuously without writing it to the qrc or TRC cells so beyond 42 gigabytes of write these drives will slow down and this is something we'd ever need to take account of in our performance tests to test out the drives I'm going to connect them in turn to the YouTube old but I looked at recently on this channel and which has these very handy external SATA connectors and as you can see we're starting with the Evo drive the TLC drive and if we go into Windows I'm going to initially test out the drives using a crystal disk mark and iso standard test using all the standard settings this certainly won't push past the intelligent turbo write limit but it'll give us some standard result and as you can see I picked up the drive here the Evo drive which formats to a nine hundred and thirty two gigabytes so let's run the tests and there we are those are the results for the Evo BTL C Drive so what I'm now going to do is to shutdown Windows so we can switch the drives over we can move across to the couvreux drive the ql c drive and then back in windows here we are we can now run a crystal disk mark again now running on the on the qo drive so let's do a test again on on that SSD and there we are we've now got the results for our qvar ql c drive and let's bring up the Evo results side-by-side so we can take a a look have a comparison and I think the first thing to say is that these are very similar results if you are worried that if you buy a ql c drive you go to get significantly impaired performance compared to a TLC drive then clearly this test suggests you won't at least with new drives straight out of the box these are clearly the best results these drives will ever deliver just to explain what we're looking at here the first line of results in crystal disk mark is a test of reading or writing very large files so this is representative of what would happen if you were copying very large sets of data between two drives and this gives us the highest results but it's not necessarily representative of all real-world performance on a computer and so the results we can see beneath there were other three rows of results or tests where crystal disk block has been writing very small files four kilobyte files and running lots of queues and process of thread simultaneously so this is much more represent of what happens when you're computed actually working writing cache files running programs in Windows etc and here I guess we could say on the very last test we've got slightly worse performance on the queue though but to be honest I think that's within the bounds of experimental error so basically in this first test using crystal disk mark we can see no significant difference between our TLC and QC drives so let's move on to do something that goes beyond the Samsung intelligent turbo right technology right I've now reconnected the Evo drive for a continuous write test of over 42 gigabytes now I know that transferring this quantity of data in one go is not something that many people do that often however if you shoot pro res or other high data rate video it's a fairly common activity and personally I sometimes recalled over 100 gigabytes in a day and in fact the pro res files I grabbed for the last segment of this video were about 34 gigabytes in size copying such files directly off the media they recorded on may bottleneck on tests so what I've done here in Windows is I've copied some files to an nvme SSD which is on this system which is much faster than either the drives with testing so I open that up you'll see we've got about 17 files here totaling about seventy five gigabytes in size these are all pro res video files so what I'll do is to copy those files and then I'll bring up the here the Evo SSD which we're going to paste the files to and I'll also splitscreen things here and bring up some clock so we can race the Evo and couvreux together and I'll go to paste and we'll start off our test and there they are they're running let's just bring that on screen so we can see everything properly initially both the drives show a very fast write speed because I forgot to tell you they've also got a ram cache I think it's one gigabyte so initially very very fast and then they'll drop down to actually writing to initially the intelligent turbo write cache so that'll be what they're doing slightly faster speed being recorded here on the cubo on the ql co-driver it's very intro sting better that's clearly what we're getting the thing it interests me is what happens when we get to the utter forty two gigabyte point well in theory the intelligent turbo cash will be filled so let's speed onto there and here we are we should be approaching that 42 gigabyte pointer should cease to be able to use the cash in the speech you go down be fascinating to see if this actually happens no evidence yet must be about this point all yes if you look at the Cubo graph there it clearly dropped dramatically in terms of right speed it's filled the cash it's filled at forty two gigabytes intelligent turbo cash has dropped down very much interestingly the Evo hasn't which I'm slightly bewildered by because I checked the specs very carefully there is supposed to be the same intelligent turbo right cache 42 gigabytes on the one terabyte Evo and couvreux Drive but this suggests that isn't true I know there was a 78 gigabyte cache on the 2 terabytes and 4 terabyte Evo's but isn't supposed to be there and the one terabyte maybe Samsung have upgraded their hardware but anyway we can certainly see here the difference between the TRC and curiosity implementations here from Samsung once you get to that cast position you've got a much lower write speed on the qrc drive at least at this quantity of data being written and we're now almost the point where the Evo drive has finished very close they're getting towards the end Evo Drive nearly finished you can do it Evo Drive there you are the Evo drive has finished on 2 minutes 41 seconds to write the 75 gigabytes of files and I know by the magic of filmmaking that's about four hundred and sixty five megabytes a second across that period of time which is very good isn't it where is the qlc drive the Qi waste clearly still going it's going to take a little while let's at speed on towards the end of the test and here we are the Q though has almost finished I keep imagining all those billions and billions of memory cells of those electrons being moved around into that charge trap flash they're fascinating to think how all that's happening as we watch these are these drastic is progress and that yes there we are the couvreux has now finished in 8 minutes and 1 second which means it crossed that period of time for the 75 gigabyte copy it achieved a 155 megabytes a second write speed but of course that speed is almost irrelevant to sight because it just depends how long you've copied fast for how big the file copy was going to be isn't it I think really what this test highlights to me is that the couvreux drive is a very good Drive the qrc Drive providing you're gonna copy that much data at once I don't bite how long it takes to do the copy you certainly couldn't be using a queue though drive here the qrc Drive from Samsung for things like actually recording video at high data rates but for most uses I'm very impressed with the QA we're actually not seeing significant performance hit unless you're continuously writing very large quantities of data today many desktop PCs are fitted with an SSD to store that operating system and applications and a much higher capacity hard drive for mass data storage however with the creation of qlc SSDs manufacturers are intent on changing this dual drive setup and allowing more and more people to have a single drive a single high-capacity qlc SSD now how rapidly we might get towards that being enorm will of course depend on the price and the capacity of qlc SSDs but my guess is that by the end of say 2020 we will have two terabyte qrc SSDs on the market for $100 or less and by the end of 2021 we will have four terabyte qrc SSD on the market for $100 or less and those are the price points in capacity I think that would become transformative now having said that absortion of you are asking Chris would you really trust a qrc SSD not least given by the low number of P cycles and my best answer to that is that only sort of three or four years ago I wouldn't have trusted and I didn't trust a TLC SSD and yet now I would trust something like a Samsung Evo as a boot drive and indeed I'm about to test out using the QL CSS they have shown you in this video as a boot drive are going to be showing you that in a future video but now that's it for this video if you enjoyed you seen here please press title like button if you haven't subscribed please subscribe and I hope to talk to you again very soon [Music] you

Channel: ExplainingComputers

Views: 597,638

Keywords: QLC SSD, TLC SSD, QLC TLC, How do SSDs work, Samsung 860 EVO, Samsung EVO, Samsung 860 QVO, Samsung QVO, what is QVO, what is QLC, Christopher Barnatt, Barnatt, CrystalDiskMark, UDOO BOLT, Intelligent TurboWrite, Samsung, Samsung Intelligent TurboWrite, TurboWrite, SSD cache, SSD test, P/E cycles, SSD endurance, SSD performance, QLC endurance, QLC performance, best SSD, EVO vs QVO, QLC SSD performance, QLC SSD test, test, charge trap flash, floating gate

Id: WACyyFF_ci0

Length: 16min 59sec (1019 seconds)

Published: Sun Aug 25 2019

Reddit Comments

[u/topm5]

All these cheap Phison S11 based Dram-less ssd are much horrible than these, having just 6-7GB of write buffer. They start at 450MB/s till 6-7GB, after that speed drops to 40-70MB/s , slower than 5400rpm hdd.

BTW, Intel 660p, 860 QVO are also QLC.

[u/rekker22]

I already purchase my ssd so i will not watch it as it will make me sad.

[u/Skully5591]

Still to regular ssds and don’t go for cheap nvmes