As a Systems Engineer designing and architecture application systems, do I need to be concerned about what it means to use Solid State Drives (SSDs) for the storage backend supporting my application?  Should the average consumer be concerned if they have SSDs or not in their computers?  What about Enterprise desktops?  Should they all have standard hard drives (HDDs) or SDDs, and does it impact their job if they don’t? What are your solid state storage options?

The short answer is YES!  Administrators, PC techs and even the traditional user should have a basic understanding of what their systems are running on, and whether it’s a Solid State Drive (SSD) or traditional Hard Drive (HDD).  They don’t need to be experts in the hard drives or quantum physics but a basic foundation can mean the difference of slow boot times on laptops to high latency on a transactional database.  This post covers why anyone that uses a computer should care what it means to run on SSDs.

Back to Basics

Hard drives are devices that contain persistent data in nonvolatile memory.  Meaning it stores the data that doesn’t go away after you would turn off your device.  A traditional hard disk drive (HDD) consists of spinning magnetic disk that are stacked together, with a read/write head on a mechanical arm which swings over the platters.  Solid-state drives differs from HDD for a couple reasons.  They do not have any moving parts, and are designed to use an array of NAND flash memory technology to store the data in cells.  The cells either store 1 bit of data/cell (Single Level Cell – SLC), two bits/cell (Multi Level Cell – MLC), or even three bits/cell (Triple Level Cell – TLC) .  The cells are arranged in blocks similar to how data is stored in the platters of traditional HDDs, but without any moving parts they are more durable than traditional HDD.

Not All Storage is Created Equal

Now that Solid State Drives having been around for some time, it has become well know that they perform much faster than traditional HDDs.  The adoption of SSD usage is growing into the mainstream consumer population as well as enterprises.  For some enterprises it has become a standard for servers and even their laptops, while other organizations may choose to deploy them only for high transactional processing servers. Either way you are getting mainstream disk performance.

SSD also has lower latency on random access and read access, because it can read data immediately from a cell.  This is a great improvement over the traditional HDD where the platter must spin the location of the data.  With SSD the performance is greatly enhanced allowing the data from the drive to be read more quickly.  This means that your system will benefit from both improved boot up times, and superior application performance.

As mentioned earlier, SSDs are classified as eMLC (enterprise grade) or MLC (consumer grade).  The key difference between the 2 is that the eMLC has better endurance (more program/erase cycles), but costs a little more.

How fast can these SSDs be, and do you really care?

The Micron M500 SATA SSDs are rated up to 80,000/80,000 random read/write IOPS each.  The PCIe P420m is rated at read 750,000 IOPS with write IOPS at 95,000.  With these kinds of statistics, Tom Cruise in his fighter jet would even be jealous.  As the traditional user, you probably do not care that you can get up 95,000 IOPS, but if your role is the database administrator you would.  SSD performance allows for more IOPS, allowing your databases to obtain excellent performance.  This benefit comes from the fact that SSD has less latency and more IOPs ensuring reliable performance.

SSD interfaces can come in many flavors from SAS, SATA and PCIe.  The interface is how the drive connects to your system, whether it’s a mobile laptop or enterprise server.  It essentially how the brain of your computer connects to the storage device.  The type of interface can contribute to bottlenecks if it is not fast enough to pass the data to the CPU, so the interface you choose must meet the needs of your application and end user expectations.  Having the fastest drive in the world can become useless if it’s held back by the interface, so choosing the correct interface to ensure that this is not an issue is crucial to your configuration.

Diving deeper, it’s been observed by many that PCIe SSDs the fastest option available.  This is due to the fact that these drives use the PCI express bus.  This bus has at least 1 or more data transmission lanes with an independent connection to the PCi controller and the expansion card.  The direct connection helps avoid any bottlenecks that could be seen with SAS or SATA connections.  So based upon these facts alone SAS or SATA should only be selected when the system or application running on the system doesn’t have high performance requirements.  Check out Stephen Foskett’s blog on “Why PCIe SSD are faster” to learn more about the difference between these disk interface options.

How long will an SSD Last?

Let’s get this out in the open!  It important to understand that all things have a lifespan:   machines, humans, animals, tape, even paper.   Eventually things erode or breakdown and need to be decommissioned or they just don’t work anymore, unless you are etching things into stone tablets. This is true for SSDs.  There are industry standards for SSDs, for the data endurance, and retention life of the drive that was developed by Joint electron Device Engineering Council (JEDEC).   A more in depth explanation of this standard, and how it relates to data retention and endurance can be found here.

The JEDEC specification for Solid State Disk (SSD) :

  • Enterprise Grade SSD – Stored at 40°C data retention at the end of the service life shall be at least three months. Enterprise grade SSDs the can have a total byte written of up to 1.9PB which is about 3 complete drive fills per day for 5 years.
  • Consumer Grade SSD – Stored at 30°C data retention shall be at least one year after the drive’s End of service life. Consumer grade SSDs are spec’d at 72TB total bytes written – which is 40GB written to the drive every day for 3 years. Some newer consumer grade SSDs have even higher endurance with a total bytes written of up to 450TB at the 1TB capacity.

When reading these standards at first glance one may get scared and think “Oh No! I will lose my data.” The reality is that these drives last years under normal use and circumstances, the specifications above are just that.  Also, those temperatures are very high and could melt a CD in your car, those are not standard working conditions.  The true End of life on a SSD is the combination of age of the device and the endurance (data written).  A brand new laptop with an SSD drive is not going to lose its data if you don’t use it for a year, the drive has not reached its life span yet.  It is also important to understand that SSD is not intended or long-term data retention or archival.  In these cases a more affordable disk type such as SATA or even tape should be utilized.  Fast expensive storage to store archived data is not an efficient use of your investment.  It’s like putting a baby seat in the back of Porsche or using your Porsche to pull a U-Haul.  Porsche’s are meant for a specific type of driving, fast and super-fast. SSD’s have speed and performance so stick with that type of data usage and move old data to mini-vans or Chevy Silverado….

What are my Solid State Storage Options? Is SSD for everyone?

Now that we have a better understanding of the performance benefits of SSD should we use SSD for all of our organizational computers and servers?   I am going to answer NO to this question, and here is why.  At the price you pay for SSD compared to a traditional HDD, being selective on what you use will provide you the best bang for your buck.

Some excellent use cases for enterprise class SSD include VDI deployments, transactional databases, or applications that requires high IOPS.  SSDs are great for laptops too, because of the fast boot times, competitive pricing,  durability, and you will never need to hear the chunking of a traditional HDD again.  Laptops are designed to be mobile, so the fewer moving parts running inside the laptop the better by reducing the risk of damage to your disk and its data.  Desktops that will be running intensive computing applications such as 3D modeling and even gaming systems would benefit from SSD.

Cases where SSD are not the best option, is a computer that is being used to do basic computing, internet browsing, or for storage or older data such as archived information or file shares. Your best solution here is a traditional HDD where you can get low cost storage and lots of it while still having acceptable performance .

Concluding Thoughts

SSDs are a great choice for when you need performance, reliability and durability.   Understanding what to expect from it will help you understand if it’s the best option for your organizational computing needs.

Sponsored Post:  Micron Technology, Inc


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