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Buying a solid state drive (often abbreviated as SSD) can be one of the best things you ever do for your computer. Whether you want to increase overall system performance or simply get a one-up on your sig rigs "awesome" factor, a SSD may be the best component you'll ever purchase. This guide will walk you through the basics of the drive, discuss the advantages and disadvantages, and help you make a purchasing decision.

What is a Solid State Drive?
Solid State Drives are physically quite different from the conventional mechanical drives that most systems use. Rather than being based on magnetic platter-disc memory, they use NAND flash to store data.

For an in-depth explanation to the fundamental basics of NAND flash, read Michael Schuette's, "The Brave New World of Solid State Drives".
While the physical properties of NAND flash allow for much faster data reads and writes from the drive, the metal-oxide transistor based design results in an inevitable degradation of the physical hardware over time.

What is degradation?
The degradation of SSD falls under two separate categories that are often confused. There is physical degradation, where the individual NAND cells deteriorate, and then there is speed degradation, caused by "junk" data.

A Solid State Drive physically degrades each time an individual NAND flash cell is written to, and then overwritten. This is called a flash cycle. The physical degradation occurs because of the way NAND flash works; over time, as the individual transistors are "written" to (a voltage is sent to change to circuit from positive to negative, representing a binary 1 or 0) they "wear out" or "loosen," to keep from getting technical.

Typically, MLC NAND flash will withstand between 3000 and 10000 flash cycles (with most leaning towards the latter) and an SLC around 100,000. Remember, a flash cycle only occurs when a cell is written to then erased, so unless your drive constantly changes the data it stores, it will last a long time. Not all cells are created equal, and some may wear out sooner than others, while some might be dead on arrival. A good controller optimized for error correction will work around this, so this is very rarely, if ever, an issue.

The speed of an SSD will slow over time due to usage, but not physical degradation. Individual cells that have data written to them aren't automatically overwritten when you delete it in your OS. If you delete a file, the OS labels the cell that holds that data as overwrittable, but doesn't actually delete the data. As the drive continues to be used, it has more and more difficultly finding free cells in which to write new data, causing a slow down, particularly when the drive "runs" out of space and must overwrite the erasable data in real-time in order to write the new data. Garbage collection utilities, whether TRIM or something like Intel's SSD Toolbox, will prompt the controller to find these overwrittable cells and restore them back to their default value.

Storage Hierarchy:
NAND flash stores data differently than mechanical drives; each byte of data is stored in a cell, which is grouped into Pages, which is grouped in Blocks, then Planes. Cells are either 1 byte large (Single Level Cell flash, SLC) or 2 bytes large (Multiple Level Cell flash, MLC). These cells are then grouped in Pages, which almost always are 4KBs (between 4000 and 2000 cells, respectively). Blocks are typically 512KBs large, made up of 128 Pages. Planes, the last step for our purposes, are often made up of 1024 blocks. It's important to understand this hierarchy, as SSDs cannot write to or erase data at each step. At the lowest possible level of the chain, SSDs can read or write data to Pages, but can only erase Blocks. Most problems with performance occur because of this process.

Disadvantages: (See also http://en.wikipedia.org/wiki/Solid-s...#Disadvantages)
In my mind, there are three main deterrents to purchasing a Solid State Drive; degradation, cost, and maturity of the product.
  • Over time, read and write speeds will slow down on all Solid State Drives. If your drive doesn't support garbage collection it will experience a significant drop in speed, in comparison to its original performance.
  • Cost per gigabyte is another huge factor. Most MLC drives weigh in between $2.00-$3.00 per gigabyte for a 40GB-120GB drive, and SLC drives usually triple or quadruple that price. SSDs are expensive as NAND flash pricing is quite high and it's still a relatively new product in a relatively new market. Overtime, this will lower, but be prepared to shell out a couple of bucks if you want to get into the game early.
  • Lastly, many products haven't really matured at this point. Many drives may offer amazing Sequential Read and Write speeds, but horrible Random Read and Write speeds. Increasing Random speeds is possible, but at the expense of Sequential, so at this point, most drives have a low point (depending on the controller). SSD controllers are another important factor to keep in mind; J-Micron being one at the worst of the bunch. It is very important to research the effectiveness of a drives controller, as it will ultimately dictate your experience.
Advantages: (See also http://en.wikipedia.org/wiki/Solid-s...ive#Advantages)
  • The biggest upside to a SSD is the pure speed they are capable of, especially when it comes to reading data. Every application you run on your computer, as well as the OS, will be significantly speedier than any mechanical drive can hope to obtain. Random access speeds are much higher as they don't rely on a read/write head to move over a disc and retrieve data.
  • Drives write data in parallel, using several onboard controllers, enabling the drive to write the data at significantly higher speeds than mechanical hard drives (mechanical drives can't write to different places at once), though there are exceptions. However, a higher-end SSD drive versus the highest-end mechanical drive will result with the SSD being the clear winner in write speed.
  • Some find their durable and silent design to be important to; SSDs have no moving parts and make no noise. Many can also endure extreme shock, temperature, altitude and vibration. If data loss is a concern, due to the physical operating environment, a SSD will be the better choice.
Keep this in mind:

Always consider both Sequential AND Random Read/Write performance. Most often, your drive, at least outside of enterprise operations, will use Sequential Reads, Random Reads, and Random Writes. Sequential writes have their place, but not for a typical home user/gamer. Sequential writes really only come into play if you install something on the drive (like an OS or application) or run an application that creates a large data file (think video or audio processing at a home level). Sequential reads load applications and the OS faster, and random reads and writes pretty much do everything else.

There is a distinct correlation between the size of the drive and the speed at which it operates. Larger capacity drives operate faster, in short, because they have more places to store data and more controllers operating to store that data.

Decide if wear to the drive is worth optimal performance. Garbage collection is available for many different drives (like T.R.I.M.), but this function causes your drive to physically degrade faster. Most, including myself, will recommend you run a SSD with garbage collection, even with degradation. I would suggest that by the time the average user wears out their drive, they would be ready to buy a new one anyways.

What is the difference between SLC and MLC?
There are two types of NAND flash, SLC (single level cells) and MLC (multi-level cells). An individual NAND flash cell holds a voltage, which is then translated into a binary number. SLC can hold 2 different voltages, one representing a high voltage (1) and one representing a low voltage (0). MLC can hold 4 voltage values known as High, Medium-High, Medium-Low and Low (00, 01, 10, 11). MLC drives are more common as they can hold 2 bits per cell instead of one, making high capacity drives much cheaper to produce. MLC cells do have a much shorter life cycle though and typically are slower than SLC. While both are SLC and MLC are available to consumers, but SLC is often seen, and priced, as enterprise hardware. Technically, SLC will last longer and some SLC based drives are faster than most MLC drives, but when it comes to price vs. performance, MLC is the better choice.

What to Look for

Typically, you use a SSD in one of two ways:
  • The SSD/s is used as a primary drive. Your OS and applications (or necessary applications if you have many) are put on the drive. All other files are stored on a secondary mechanical drive (usually a 500GB-2TB 7200RPM drive).
  • All storage is done on the SSD/s. Everything loads faster, but this is much more expensive (consider the cost per GB for a 100GB+ drive alone).
Most users, enterprise setups withstanding, use a SSD as a primary drive and store everything else on a mechanical. This is much more cost effective, and still shows off what solid state drives are best at, increasing everyday functionality. A storage system made only from SSD/s will blow you away as much as it will blow a hole in your pocket. Obviously, everything on a SSD means everything will be loaded or written faster, but often this is overkill for an average user, and the difference probably isn't worth for most.

If you use the OS and its features, a few select applications (or maybe a game or two) you can get by with a 40-60GB drive (paired with a 7200RPM drive for any file storage). If you want to keep a lot of applications on your drive, look at drives that are 100GB+. ALWAYS keep in mind that you should keep 15-20% of your drive free for optimal performance.

After deciding what you want to use the drive for, decide your budget. I recommend doing this second, as you are better off purchasing a setup you want (and waiting for it) rather than cheaping out on a setup that won't offer you the same performance.

Recommended Drives (my own opinion, highly influenced by the others on this forum):

The drives I see recommended for a SSD/mechanical setup are as follow:
Significant updates to current SSD lineup will change around year-end. Next gen SSDs are going to be available in the foreseeable future.

For some really good real-world performance figures for various SSDs, check out TheDreadedGMan's AS SSD Benchmark thread or Fletcher_Carnaby's CrystalDiscMark Benchmark thread

This is a recap of the knowledge I've gained as I've researched Solid State Drives. I would highly recommend reading Anandtech's excellent article on Solid State drives as well as the two part series The Brave New World of Solid State Drives, by Michael Schuette.

Remember this is my opinion and I am by no means an expert, so if you have any suggestions for this guide, please post them! I realize how much work it can be to research this topic, so I want to make that process easier.
 

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Great guide, +rep!
 

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Discussion Starter #5
Quote:

Originally Posted by Kiggold View Post
Great write up man! OCN keeps pushing and pushing me to get the Intel X-25M....
+Rep
Mines at the Purolator store

I work tonight... have two days off... oh man, Intel goodness (2 X-25 Vs in that same package)
 

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Discussion Starter #8
Quote:

Originally Posted by ardentx View Post
Where are the Corsair X series drives and the new Corsair force series? they are two of the better drives around and are seriously under represented.
I haven't done enough research on the Corsair drives to make a good recommendation. I will look into these, and if they fit the bill, they will be added.
Would you recommend any drives in particular?
 

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Discussion Starter #9
Just threw the X-25M in today with a Seagate Baracuda as a secondary storage volume.
Need to flash my 120GB OCZ Summit, install my X-25 Vs in a RAID 0 (waiting for new case), and compare them versus two 30GB Kingston SSD V-Now series in RAID 0.
Oh SSDs, how you consume me
 

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Discussion Starter #12
On my next couple of days off, I'll post some results for an X25-V RAID 0 versus a Kingston SSDNow V (30GB) RAID 0.
While I'm at it, I'll run HD Tune on my OCZ Summit; not sure why that drive is never mentioned online (performs pretty respectably)

Should I add info on flashing drives?
 

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Quote:

Originally Posted by mini1337s View Post
On my next couple of days off, I'll post some results for an X25-V RAID 0 versus a Kingston SSDNow V (30GB) RAID 0.
While I'm at it, I'll run HD Tune on my OCZ Summit; not sure why that drive is never mentioned online (performs pretty respectably)
I look forward to it
Don't forget that most people getting into ssds probably wont be jumping right into raids, so some regular one vs one action would be great too


Quote:

Originally Posted by mini1337s View Post
Should I add info on flashing drives?
You mean like the firmware?
 

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i have one of these 60GB OCZ Vertex, great, boots on my rig in about 10 seconds
 

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so you are saying that SSD have more disadvantages than advantages?

my friend,SSD doesent degrade over time because of trim
 

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Quote:


Originally Posted by Eduardv
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my friend,SSD doesent degrade over time because of trim

Yes they do. And TRIM has no effect on the number or Read/Write cycles, that's fixed in place. You should ream up on what TRIM is.

Also, SSD's currently are more disadvantageous than advantageous, but this is because it's a young tech.

If it was the other way around, you'd see servers and data centers using SSD's.
 

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Discussion Starter #18
Quote:


Originally Posted by Eduardv
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so you are saying that SSD have more disadvantages than advantages?

my friend,SSD doesent degrade over time because of trim

It does. Basically, NAND flash's lifetime is dictated by its max flash cycles. A flash cycle is a write to the drive followed by an erasure. MLC can go through 3K to 10K flash cycles and SLC roughly 100k. When TRIM goes through and erases the data from the drive, freeing up those cells set as being overwritable but still containing data, it completes the flash cycle. Since TRIM makes the drive endure more of these, the physical circuit's quality degrades.

Quote:


Originally Posted by Michael Schuette's The Brave New World of SSDs

Every program process followed by an erase is called a flash cycle or else a program/erase (P/E) cycle. NAND flsh can sustain many cycles, depending on whether it is SLC (100,000 cycles) or MLC (10,000 - 3,000 cycles depending on manufacturer and process geometry). However, cycling a NAND flash cell entails extremely high electrical fields that can exceed 10 million volts per cm, which is needed to force the electrons to pass through the oxide layer in either direction. Over time, this causes degradation of the oxide layer by causing atomic bonds to break within the oxide layer proper and also at its interfaces with the floating gate and the substrate. The intermediate result is trapping of electrons at the broken bond sites with the oxide layer acquiring negative electrical charges. As a consequence, the erase process becomes slower whereas the programming becomes faster.

I plan on adding more to this guide, but I've just been extremely busy over the past bit. Work and such, but I'll get a couple free days eventually.
Glad it's helping people.

EDIT:
As for the advantages vs. disadvantages, while there may be more disadvantages (and keep in mind this is my opinion), the advantages FAR outweigh the disadvantages.
 

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Well i dont see the difference with physical HDD's the clunky ones will fail much faster than SSD,so in terms of lifecycle,and ssd endures more than a HDD.

and it will always be faster .
 
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