Differences in SSDs

[MichaelGavel]

How can you tell what is and isn't a good SSD?

Is it soley based on brands? Are there different chipsets? Certianly speed and reliability are key factors, but what effects these, and how can you tell them apart?

 

- Thanks, Mike

[Captain_WD]

How can you tell what is and isn't a good SSD?

Is it soley based on brands? Are there different chipsets? Certianly speed and reliability are key factors, but what effects these, and how can you tell them apart?

 

- Thanks, Mike

 

 

Hey MichaelGavel,

 

The best way to see if a drive is good or not is to look around the internet for opinions, reviews, benchmarks and comments. The more you get, the better and more accurate idea you'll have about the product. I'd say look around here on the forum for what are the mostly used drives and see which of them would meet your needs.

 

You can read some info on the different cells that SSD can have and see the ups and downs of them.

 

Captain_WD.

[MG2R]

How can you tell what is and isn't a good SSD?

Is it soley based on brands? Are there different chipsets? Certianly speed and reliability are key factors, but what effects these, and how can you tell them apart?

Listen to Captain_WD. Also, it's good to realise that there are only a few actual controller manufacturers and flash manufacturers. Most companies will just buy specific controller and flash chips and put them on a PCB. So it isn't as simple as SSD brand X is more reliable than SSD brand y. Doing your research is your best bet.

[EmeraldFlame]

How can you tell what is and isn't a good SSD?

 

The best way is to read professional reviews over them and looking at real world benchmarks. Personally I prefer reviews from PC Perspective then Hardware Canucks just slightly below them. They both go into a lot of detail about each SSD's performance, underlying technologies, and other factors that affect performance.

 

Is it soley based on brands?

 

No, it isn't. However some brands do tend to have better products. Samsung overall has had great SSD products throughout the generations along with Intel. On the flipside, OCZ in the past has had problems with immature failure and Kingston has had a PR nightmare by committing 'bait and switch' style sales. However, Samsung and Intel have not been without fault, and OCZ and Kingston have had some great products too.

 

Are there different chipsets?

 

There are! Sandforce based chipsets where some of the earliest high performance SSD controller chipsets, and they are still popular contenders today. However many companies have developed their own controllers as well with varying degrees of performance. In the SATA SSD world, Samsung's chipsets have some of the best performance.

 

Certianly speed and reliability are key factors, but what effects these, and how can you tell them apart?

 

These definitely are the major factors with storage mediums. And every SSD is slightly different into where it falls. However, three major NAND structures have popped up over time.

• SLC (Single Level Cell) - Fastest technology and longest lifespan. However, significantly more expensive than the other technologies and often offered in smaller capacites. Every NAND cell only stores a single bit of data. Typically seen in enterprise equipment and top of the line enthusiast equipment like the 850 Pro.
• MLC (Multi-Level Cell) - Slower than SLC, with slightly shorter lifespan. But significant cost savings over SLC along with higher availability of larger capacities. This structure allows 2 bits to be stored in every NAND cell, which means to reach the same capacity as SLC, you only need half the NAND cells. Although slower than SLC, it is fast enough for most consumers, and most drives using it can still completely saturate SATA3 6Gbps. While lifespan is technically shorter than SLC, it is still unlikely that you would ever see the EOL of a drive using MLC during normal usage. Seen in most consumer grade SSD's.
• TLC (Tri-Level Cell) - Much like MLC, but able to store 3 bits instead of 2. Once again, cheaper than SLC/MLC but with a shorter lifespan yet, and slightly lower performance. However, most drives are still fast enough to saturate SATA3, and still have long enough lifespan that during normal use you will not see the end of life on it (writing at 100% of the possible speed 24/7 which is a completely unrealistic scenario, the drives will still last for years). Often seen in budget ssd's like the Samsung Evo series.

There are other technologies at play too on the firmware side. Samsung has Rapid mode than can use your system RAM as an even faster cache for important files and cached writes.

There are also different interfaces now too. SATA3 SSD's are by far the most common, but because of the limitations of SATA3, these top out around 550MBps. PCI-E SSD's like the Revo Drive or the Intel 750 series are also out there. Using the PCI-E lanes gives significantly more bandwidth so that 550MBps limit no longer applies. The intel 750 series  is rated at a read speed 2.4GBps and 1.2GBps write speed. There are also M.2 SSD's, M.2 is essentially a smaller form factor that allows access to PCI-E lanes. They are typically slower than full add in cards like the 750 series simply because of size restraints, but can also be faster than older SATA3 SSD's. There is also SATA-Express, which looks like 2.5 SATA plugs, but is also tied to the PCI-E lanes for higher performance. However, SATA-Express has had very slow adoption, and as far as I am aware there aren't any consumer drives that use it yet.

And last, a newer emerging technology is NVMe, used by the Intel 750 series, which is replacing AHCI. NVMe and AHCI are technologies that deal with how your computer sends read and write requests to your storage, along with how the storage handles those request. AHCI was developed for hard drives, and while absolutely great for that, has shown to be a bottle neck for the increased speeds of SSD's. NVMe was developed specifically for SSD's and has so far proven to be a much better technology for them allowing for increased queues and queue depth which can dramatically improve random small IO (which are normally the most common operations like opening a program or booting up a computer). NVMe tends to have lower latency than AHCI which once again really helps for small random IO. There are very few drives currently using it, but it looks like the industry will be shifting that direction.

There is obviously more to any subject, but I tried to give you the highlights of the current market in as layman's terms as possible while trying to remain accurate and true to what the technologies actually do. If you have any questions, please feel free to ask.