An SSD Purchase Guide!

Discussion in 'Computer Memory and Hard Drives' started by OmniDyne, Jan 3, 2019.

  1. OmniDyne

    OmniDyne Active Member

    Messages:
    545
    Updated 7/28/2019

    It's never been a better time to purchase an SSD! Whether you're new to the SSD game, looking to upgrade or replacing your older SSD, this guide will be a tool to assist you, as a consumer, in making a more informed purchase.

    An SSD, or Solid State Drive, can be equated to a large super-fast flash drive that is rapidly replacing HDDs (hard disk drives) as the preferred method of housing Windows, Mac, and other operating systems (OS).
    This is because SSDs are multitudes faster than HDDs and are more reliable. SSDs have no moving parts.
    Smartphones such as Android and Apple devices use SSD storage.

    In some ways, an SSD can be compared to a computer; it uses a processor and memory, for example.

    As is typical with computers, not all SSDs are created equal. Brand name has nothing to do with a quality SSD; every manufacturer makes excellent SSDs and every manufacturer makes less than desirable SSDs.



    _________________________________


    Contents

    Section 1 - Form Factor and Protocol

    Section 2 - NAND Flash Type and Layering

    Section 3 - Controller, SLC Caching, DRAM Buffer, HMB, and Over-Provisioning

    Section 4 - Brand and Model Purchase Segment

    _________________________________


    Section 1 - Form Factor and Protocol


    The most common SSD form factors are 2.5" drives and M.2 drives.


    2.5" SATA SSD


    CNT.png




    This SSD uses the same SATA interface that a typical hard disk does. Uses the AHCI protocol.


    M.2 SSD
    CNT2.jpg



    The M.2 SSD connects directly to the motherboard via an M.2 connector. It can use the SATA bus or the PCIe bus. M.2 SSDs can support different speeds; PCI-Express 3.0 x2 or PCI-Express 3.0 x4, respectively.

    M.2 SSDs are manufactured in different dimensions and sizes. This will be written as 2242, 2260, 2280 or 22110.

    For example:

    WD Blue M.2 2280 1TB.

    22 is the width. The remaining numbers represent the length, so 2280 = 22mm wide x 80mm long.

    You will need to consult the motherboard support page or manual to find which M.2 SSDs will be compatible with your system.


    M.2 Module Keys


    M.2 SSDs use defined keys and notches for the interface. For M.2, the most commonly used keys are:

    • B - Can support both SATA and PCIe interface/ protocol; supports up to PCIe x2 speeds on PCIe bus.

    • M - Can support both SATA and PCIe interface/ protocol; supports up to PCIe x 4 speeds on PCIe bus

    • B+M - Can support both SATA and PCIe interface/ protocol; supports up to PCIe x2 speeds on PCIe bus.

    M2-FAQ-Q17_BOTTOM.png

    Picture source: https://www.kingston.com/us/ssd/system-builder/m2_faq


    Important Note: A "B" connector will not fit into an "M" port on the motherboard and vice versa.

    NVMe - (non-volatile memory express) is a protocol used over the PCIe bus. An NVMe SSD enjoys the benefit of lower latency and extremely high speeds; it is superior to SATA in every way. It takes full advantage of the PCIe x4 lane and is mostly for pro-consumers and workstation users. However, this massive speed increase is hardly a benefit to the typical consumer, especially considering NVMe SSDs. The vast majority of consumers will not notice the difference in real world performance between a SATA SSD and an NVMe SSD. With that being said, NVMe SSDs are priced similar and often cheaper than SATA based SSDs at larger capacities.



    Section 2 - NAND Flash Type and Layering


    Just like a flash drive, an SSD uses flash memory. This particular flash is called NAND flash; it's used to store data and is a type of nonvolatile storage technology that does not require power to retain data. The most common types of NAND flash are:

    • SLC - Mostly used for critical enterprise storage devices, this flash is extremely expensive, but extremely fast and durable. It is non-existent in the consumer-grade SSD realm.

    • MLC - MLC flash is a "step down" from SLC flash. It's cheaper and not nearly as fast or durable as SLC, but its lower price tag made it a viable option for consumer-grade SSDs. MLC is no longer used by the majority of manufacturers of consumer-grade SSDs, however, you can still find MLC SSDs for sale on the market.

    • TLC - Until QLC flash was released, TLC NAND flash was the cheapest and densest available. Once used only for extremely cheap low-end SSDs, TLC is now employed in almost every SSD (including Samsung) and is more than adequate for consumer-grade SSDs.

    • QLC - The newest version of NAND flash. QLC NAND is capable of 33 percent higher array density. This means QLC SSDs, in theory, will be much cheaper and much larger than previous SSDs.

    About QLC NAND

    QLC NAND was recently released for use in consumer-level SSDs, including by Samsung with their QVO line and by other manufacturers such as Intel with their 660p NVMe SSD; ADATA and Crucial have also released variants. QLC is important because it reduces cost and increases density exponentially, resulting in cheaper and smaller SSDs.

    There is a lot of misinformation regarding QLC flash. The vast majority of computer users should worry none about the longevity or performance of QLC NAND. Manufacturers have effectively mitigated the performance and endurance loss associated with QLC NAND by means of intelligent controller firmware and caching algorithms. The typical consumer will not realize any difference in terms of performance or longevity when using a QLC based SSD.

    Note: For consumers, endurance ratings should largely be ignored. Although QLC flash has one-third the endurance of TLC, manufacturers have developed techniques that make this a non-issue. For example, the Intel 660p NVMe SSD utilizes what's called a dynamic SLC cache; this enables the 660p to treat up to half of the available QLC memory as SLC flash, drastically improving performance and endurance. As the drive fills up, the cache gets smaller and more QLC blocks will be made available. In theory, the SLC cache could be fully exhausted, but for most consumers this would be completely unrealistic. Even if a consumer were able to write directly to QLC, speeds would be consistently well above hard disk speeds; comparable to slower TLC. QLC will improve as the technology progresses.

    Layering2.jpg
    Picture source: https://www.anandtech.com/show/13752/anandtech-year-in-review-2018-ssds


    Flash Stacking

    • 2D or planar NAND - Originally, consumer level MLC and TLC SSDs were produced using what's called 2D planar NAND flash. This means the flash was placed side by side, as if on a plane.

    • 3D NAND - All newer TLC and QLC drives use 3D NAND flash. This means that the flash is stacked vertically, yielding faster speeds, increased longevity, and improved power requirements. This technique and technology massively improves density.

    64-layer 3D TLC has essentially met or surpassed 2D MLC in performance and reliability.

    Note: One should avoid older style 2D or planar SSDs, MLC or TLC. These drives have decreased reliability and endurance compared to most 3D TLC drives and cost the same or often less.


    Flash Layering

    NAND manufacturers have developed techniques for layering NAND flash. This is an incredibly complicated process. Basically, just as with 3D stacking, the flash can be layered to improve density, therefore increasing drive capacity in smaller spaces; this can create issues though because cells will interfere with each other the closer they are layered, however, it's not quite this simple as different flash manufacturers are better than others at this process and some layering techniques are better than others.

    Newer generations of SSDs use 64-layer and 96-layer configurations. Older drives use 32-layer. 32-layer 3D TLC is acceptable, but newer layering technologies are better overall.



    Section 3 - Controller, SLC Caching, DRAM Buffer, HMB, and Over-Provisioning


    An SSD utilizes an incredibly complicated structure of components and technology. On the consumer level, these will be the most important parts of an SSD to look out for:

    • Controller - Just like a computer, an SSD uses a processor (or controller). This is one of the most important elements of an SSD. A controller will dictate performance and endurance.

    • SLC Caching - This is a technique used in SSDs where a portion of the TLC or QLC NAND is treated as SLC flash. This drastically improves write performance because information can be written to the much faster SLC cache and later moved to the slower TLC or QLC flash. Some SSDs have a large SLC cache; others not so much. For consumers, this isn't the most important factor, but it can help if you're using the SSD to store large files such as games. An adequately sized SLC cache is especially necessary for 2D TLC SSDs because writing directly to the flash is so slow that it can cause hard disk-like performance.

    • DRAM Buffer - This is a DRAM module, usually external of the NAND flash. It helps with writes, especially small or short writes to the flash, making it ideal for an operating system. This is because the OS and programs/ apps rely heavily on random read/ write performance and DRAM is much, much faster than flash. Basically, the OS will store a map of the data on the DRAM chip, allowing the controller to more efficiently store the data it writes, therefore drastically increasing endurance and speed. DRAM generally drastically increases the life of an SSD because less writes are needed to store a piece of information.

    • DRAM-less - This is where a manufacturer produces an SSD without the external DRAM chip; presumably to save costs. This causes the OS data map to be stored directly on the NAND flash, increasing the effect known as "write amplification". A DRAM-less SSD suffers from substantially lower endurance and performance; the life of the flash is reduced drastically as a result. This is especially noticeable with 2D NAND SSDs; they will stutter and suffer hard disk-like speeds and fail more often. DRAM-less SSDs are less reliable by nature. Performance decreases are especially noticeable on a full DRAM-less SSD and manufacturers rely more heavily on a process known as "over-provisioning" to combat its deficiencies in these drives because it takes many more writes to store a piece of information.

    • Host Memory Buffer - Host Memory Buffer, or HMB, is a newer technology used in DRAM-less NVMe SSDs. This allows the OS to store the data map on available system memory (such as RAM), therefore increasing performance and longevity. It isn't perfect and doesn't replace DRAM completely, but it helps create low cost SSDs without such a massive hit to endurance and performance. (This feature is drive specific and is currently only supported by Windows 10 post-Creator's update and Linux; supposedly older versions of Windows can support HMB with driver updates, but is not supported natively)

    • Over-Provisioning - SSD manufacturers implement what's called over-provisioning. This is an area of the NAND flash that is inaccessible to the user and is not visible. This process greatly increases endurance and performance of an SSD. In the past, manually over-provisioning was recommended; this is no longer necessary.

    Note: In the current market, a DRAM-less SSD should mostly be avoided by the majority of consumers. DRAM SSDs typically cost the same or slightly more than their DRAM-less counterparts.

    Note - DRAM Buffer: The OS stores a map (translation table) of the information on the DRAM buffer and the SSD uses this map (translates) to retrieve and write information to the flash. This significantly reduces wear and increases performance because SSDs do not store information like a spinning hard disk; an SSD must spread wear evenly across the NAND flash.

    Without the DRAM buffer, the map is stored directly on the NAND flash. This is an issue because flash is significantly slower than DRAM and this process causes the SSD to inefficiently write to the flash since it isn't given time to appropriately allocate the writes. The SSD is then forced to make several more writes just to store a piece of information, drastically reducing endurance and performance because the SSD has to move the information around the flash and write an entire page just to make small changes to the translation table.

    The majority of manufacturers will not specify on websites or packaging if an SSD contains DRAM. It's best to consult reviews and guides for this kind of information.

    Note: It's best to update the firmware on an SSD after initial installation. Controllers are constantly improved and having the latest firmware version can improve performance and endurance.



    Section 4 - Brand and Model Purchase Segment


    Now that we're armed with the information we need to make an informed decision, we can create a guideline for purchasing an SSD. Keep in mind that sales happen constantly, so prices will go up and down.

    Important Note: M.2 PCIe NVMe SSDs have largely achieved parity with SATA based SSDs in pricing at 1TB. At this point in time if your motherboard supports M.2 NVMe, always go that route.

    Drives will mostly be placed in order of performance based on reviews from professionals. If you're not looking for a workstation drive you can ignore performance; go for the better deal.

    The going rate for a competitive SSD at 1TB is approximately $100 (US), plus or minus $10.


    SATA and M.2 SATA

    Some of these SSDs are no longer in production; pricing on these SSDs may be excessively high, but sometimes deals can be had.

    Samsung 860 EVO

    Intel 545s

    Crucial MX500

    WD Blue 3D and SanDisk Ultra 3D


    BUDGET SATA - OS and Gaming Only


    Again, pricing will vary greatly based on availability. Some of these SSDs are no longer in production.

    ADATA SU800 or SX850

    Team Group L5 Lite 3D

    HP S700 Pro


    M.2 PCIe NVMe

    ADATA SX8200

    HP EX920

    Corsair MP510

    Addlink S70

    MyDigitalSSD BPX Pro

    Silicon Power P34A80

    Sabrent Rocket

    Inland Premium

    Team Group MP34


    Budget M.2 PCIe NVMe


    WD Blue SN500

    Crucial P1 - QLC NAND

    Intel 660p - QLC NAND

    Note: QLC NAND appears to still have low yields so pricing is hardly competitive, if at all, with 3D TLC NAND based SSDs. The 660p has been seen at approximately $80 on sale, so you could save $30 if you keep an eye out for it.

    The reason QLC NAND based SSDs are in the budget realm is because, technically speaking, their performance is lower than SSDs utilizing 64-layer 3D TLC NAND. However, this does not mean consumers will notice any difference when using the operating system or gaming. 99 percent of consumers will notice no difference between QLC based SSDs and TLC based SSDs.

    HP EX900
    This SSD utilizes HMB (Host Memory Buffer) instead of an external DRAM buffer. Only Windows 10 Creators Update and Linux support HMB natively. If using an unsupported OS, the EX900 will operate as a DRAM-less SSD.
     
    Last edited: Jul 29, 2019
    jevery, StAugnative, _Kyle_ and 5 others like this.
  2. Intel_man

    Intel_man VIP Member

    Messages:
    5,704
    You might want to at one point expand this to include 2.5" NVME drives that use the U.2 connector, AIC's, and Intel's Optane SSDs (not to be mistaken for their Optane Memory cache drives).
     
  3. OmniDyne

    OmniDyne Active Member

    Messages:
    545
    I thought about including these in the guide, but I think it would muddy up the guide, so to speak. At the consumer and pro-sumer level, U.2 is all but dead. Optane SSDs aren't able to compete in the consumer space. Considering M.2 is the defacto standard, AICs are also dead in the consumer/ pro-sumer space.

    This guide is for average users, or maybe slightly technically inclined. If you have the money, M.2 NVMe is more than sufficient. If you don't, M.2 SATA is more than sufficient. If you're looking for budget drives, 2.5" SATA is more than sufficient.

    Actually, prices change day to day, which is exactly why I included the links. SSDs constantly go on sale.

    This forum is reading ha.
     
    Last edited: Jan 3, 2019
    Laquer Head likes this.
  4. AlienMenace

    AlienMenace Well-Known Member

    Messages:
    1,023
    Besides the links for buying the SSD's, it is still a good read to some of us. ;)
     
    Darren likes this.
  5. Intel_man

    Intel_man VIP Member

    Messages:
    5,704
    Then the title should really be "An SSD Purchase Beginner's Guide".
     
  6. Darren

    Darren Moderator Staff Member

    Messages:
    12,041
    What a needlessly tough crowd. Looks solid, lots of info I don't know. Will give it a full read when I swing for a 1TB SSD.
     
  7. OmniDyne

    OmniDyne Active Member

    Messages:
    545
    But it isn't just for beginners in my view. Optane isn't realistic for consumers, pro-sumers, or workstation users; $500 for 480GB and $1000+ for 1TB is hardly justifiable; U.2 and AIC are generally in the same boat and the market reflects this - enterprise adoption has also been stagnant. M.2 NVMe is more than sufficient for mostly anything workstation and below other than maybe for niche uses, but this can be said about anything. I personally dont think someone could be labeled as a beginner if they aren't using or purchasing specialized hardware.

    As I stated at the beginning of the guide, it's a tool to assist, it's not the ultimate end all be all of SSD guides and I encourage research within it. That being said, I appreciate the criticism.
     
    Darren likes this.
  8. Intel_man

    Intel_man VIP Member

    Messages:
    5,704
    It's one thing to not recommend the product because of it's high cost and low adoption, but it's another thing to not provide basic information to the technology. I'm not saying your guide sucks, but more like consider adding the ones mentioned in future revisions when time permits.

    A simple "here are a few upcoming/new technologies to keep an eye out for" list would suffice. This list is for technologies that would one day lower in price to the point of being affordable for the mass. You can probably add Samsung's Z-Nand technology on that list as well. There's probably more out there that is worthy of a mention.

    As you've said, this is a tool to assist and to provide general knowledge about this topic. You can hardly get people to encourage research within if it doesn't even get mentioned.
     
  9. Cromewell

    Cromewell Administrator Staff Member

    Messages:
    15,357
    IMO, if you already know what you are doing you aren't going to read the guide, so labeling beginners is unnecessary.
     
  10. OmniDyne

    OmniDyne Active Member

    Messages:
    545
    I definitely understand what you're saying, but U.2 is dead though. Like it was born and then it stuttered and died. There's one motherboard on Newegg that has a U.2 connector and it's a Z170. It does not exist outside of the enterprise/ server realm. It could return, I suppose. And if it does, I'll update the guide accordingly.

    As for Optane SSDs, Micron and Intel are ending their joint venture; development of 3D Xpoint. The future of 3D Xpoint is unknown. We know that Micron has its own plans for 3D Xpoint - QuantX TBA in late 2019 (and then buy Intels $1.5 billion stake). It's not entirely known what Intel will do. Gen 2 of 3D Xpoint is expected to release in mid-2019. I hardly call this a future/ upcoming technology. At this point it failed in the market; consumer and enterprise. If the 1TB Intel Optane SSD dropped in price by 80 percent tomorrow, then yeah, I'd update the guide ASAP.

    Z-NAND is purely enterprise solution based. In my view, this is the problem many other guides have; making users wade through a flurry of information that doesn't pertain to them. M.2 is still so misunderstood, and it's easy to see why. I might as well just throw in 10 paragraphs on MRAM while we're at it (haha I kid, I kid).

    Just look at this guide from Tom's Hardware: https://www.tomshardware.com/reviews/ssd-buying-guide,5602.html

    What a mess. I don't understand how they expect anyone (even more technically inclined consumers) to absorb information from that article; sadly it's the first result that comes up in a Google search for 'SSD Guide'. I feel like it's so out of touch with even workstation users. Workstation users or pro-sumers may be far more knowledgeable in the software side than the hardware side. Would anyone recommend that guide to them? I personally don't think so. I tried to focus on simplicity a lot in this guide.
     
    Last edited: Jan 5, 2019
  11. mep916

    mep916 Administrator Staff Member

    Messages:
    10,993
    Great work, OmniDyne. Thanks for your contribution to the forum. These guides take some time and effort, much appreciated.
     
  12. Intel_man

    Intel_man VIP Member

    Messages:
    5,704
    Statements like this really lowers the credibility of the topic you're trying to write. Intel's non Optane nvme drives are offered in U.2, AIC, and M.2 form.

    https://www.msi.com/Motherboard/meg-z390-godlike
    https://www.msi.com/Motherboard/Z370-GODLIKE-GAMING
    https://www.msi.com/Motherboard/X370-XPOWER-GAMING-TITANIUM
    https://www.msi.com/Motherboard/X370-GAMING-M7-ACK

    Plus pretty much every evga Z series mobos have U.2.

    They're splitting. Development is going to continue independently for gen 3. There is a chance that Micron will buy out Intel's part though after the split.

    Z-NAND has currenly been rolled out for enterprise users. It's not projected to be an enterprise exclusive later down the road. Similar to how Optane was rolled out first to enterprise users, then to the high-performance consumer segment. Also, Tom's Hardware is not what it use to be anymore.
     
  13. OmniDyne

    OmniDyne Active Member

    Messages:
    545
    The EVGA Z390 FTW doesn't/ won't include U.2. EVGA Z370 Classified K does not, either.

    Some of those are $500+ motherboards. So we have what seems to be specific boards supporting super expensive server "enthusiast" storage and Optane "not really sure who this is for" storage.

    I noticed some X299 motherboards don't come with U.2, or sometimes they support an adapter (https://www.gigabyte.com/Motherboard/X299-UD4-rev-10#kf).

    Somehow when I searched on Newegg I couldn't find U.2 support, probably user error. Either way, I didn't state in the guide that U.2 is dead. But it kind of is. It almost seems like a random thing when U.2 is thrown on a motherboard.

    Which drives? The 600p series and 660p are not.

    Projected. Maybe a guide should be created based on projected technology; maybe a guide for the high-end consumer segment where money is no object?
     
    Last edited: Jan 6, 2019
  14. Intel_man

    Intel_man VIP Member

    Messages:
    5,704
    Interesting they dropped it for the 300 series apart from the Dark boards. They've had U.2 since Z170 on pretty much their entire lineup with the exception of their Stinger ITX boards.

    Those were a sample list of motherboards that had U.2 and is not all of the motherboards that have it.
    Anyone who needs ultra low latency access storage and ultra fast random read/write performance.
    No, you just completely did not mention it's existence. From the very start, I was suggesting writing a sentence on U.2 and what sort of drives use them. No one told you to write a 3000 word essay on it. The only connector that's really dead is SATA-Express.
    Intel 750. They were the main competition to Samsung's 950 Evo/Pro drives. I am surprised you aren't familiar with them.

    It's really a matter of time really. Once competition catches up and the "next big thing" isn't quite ready yet, you'll see the enthusiast stuff increase in yield efficiency and drive the cost down.
     
  15. OmniDyne

    OmniDyne Active Member

    Messages:
    545
    So, like enterprise? Or niche CDN roles?

    Drives manufactured for enterprise/ niche workloads.

    Yes, because U.2 does not currently cater to anything below enterprise solutions. There are no U.2 drives manufactured that serve consumers, pro-sumers, or even workstation users in a realistic sense; these drives are not competitive. The market reflects this.

    And the guide will be updated to reflect this, when the time comes.
     
  16. Intel_man

    Intel_man VIP Member

    Messages:
    5,704
    No? Think harder. What else can benefit from the low latency access?

    So you're saying the 950 Evo/Pro is niche and for enterprise only?

    Do you even actually look up what the Intel 750 was targeting? Enthusiasts. Seriously, do some research before being wrong again.


    ===============================
    You do might want to mention that the M.2 "E" Key is for WLAN/Bluetooth cards and don't get mistaken that for a slot that can take a M.2 2280 ssd. Motherboard manufacturers aren't great at telling the consumers that.
     
  17. OmniDyne

    OmniDyne Active Member

    Messages:
    545

    Statements like this really lower the credibility of the topic you're trying to write.

    https://www.anandtech.com/show/9090/intel-ssd-750-pcie-ssd-review-nvme-for-the-client/10


    Why you brought the 3 year old $1,000+ 1.2TB 750 into this, I don't know, but it doesn't support your argument that U.2 is relevant in today's market and warrants addition to the guide.

    Again, there are no U.2 drives manufactured that serve consumers, pro-sumers, or workstation users in a realistic sense.
     
    Last edited: Jan 6, 2019
  18. Intel_man

    Intel_man VIP Member

    Messages:
    5,704
    Look, go defensive all you want. I'm not here to argue, was merely trying to tell you what I would've wanted to see more information about so that the guide's more inclusive of everything that is out there.
     
  19. johnb35

    johnb35 Administrator Staff Member

    Messages:
    41,656
    Ok. I asked Omnidyne to get a thread going for SSD's on what would be good to get and what wouldn't be good to get. I just wanted a decent amount of items listed to help other users. I mean at this point, Sata, M2, NVME drives are what everyone is buying. When this U2 becomes more relevant, it can be added along with other new additions. I didn't mean for him to hear flack about not adding this type of drive or that type of drive. We don't have anything like this already posted. I will actually be doing some digging into this U2 connection to see how often its used and report back. I myself didn't even know U2 drives were a thing.
     
    porterjw likes this.
  20. OmniDyne

    OmniDyne Active Member

    Messages:
    545
    Don't take my previous comment as being defensive ha. I was simply poking fun at you.


    You are and you did, but honestly I enjoyed the debate. As I said before, I do appreciate your criticism.


    That's not accurate.

    Everyone makes mistakes or misses things from time to time. But when the opportunity presents itself to inform others, your approach is sometimes quite ineffective. For example, 10 months ago I broached the subject of DRAM-less SSDs; the brazenness of your responses in that thread accomplished nothing but dissension. You should consider the fact that talking to people in different manners yields varying responses. Your goal in this forum shouldn't be to run people over and you could have handled this thread in an entirely different way.

    But again, I appreciate the criticism. I'll consider everything you've mentioned and take a fresh look at U.2.
     
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