| Much has been written about solid state disks (SSDs) | | | | of HDDs a crucial point in technological purchases. The |
| becoming the next big thing1 in the IT industry(1). But | | | | typical access time for a Flash based SSD is about 35 |
| as to whether or not we have enough knowledge of | | | | - 100 s, whereas that of a rotating disk is around |
| how it will revolutionize the industry is a different | | | | 5,000 - 10,000 s. That makes a Flash-based SSD |
| question. How much do we really know about SSDs? | | | | approximately 100 times faster than a rotating disk. |
| If we are to ask people on the streets, it wouldn't | | | | This however raises another point - what's the |
| come as a surprise that they dont know much of | | | | benefit of a high-speed SSD when the entire system |
| what an SSD is. Even if they do know, most | | | | cannot support it? The evolution of CPUs in terms of |
| probably it would be limited to a USB pen drive, a | | | | performance has far surpassed the development of |
| CompactFlash or a Secure Digital card, which are | | | | the data storage system. The HDD is actually limiting |
| more on the consumer side of the storage industry. | | | | the potential of a computer system when they are |
| Technically speaking, they are not wrong. Most web | | | | not able to keep up with the performance of the |
| definitions describe an SSD as a high-performance | | | | other components, particularly the CPU. If an HDD is |
| plug-and-play storage device that contains no moving | | | | replaced by a high-speed SSD, the performance |
| parts. Therefore, given that most of the | | | | would significantly improve. The resulting system |
| aforementioned mobile disk storage devices contain | | | | would be a high-powered set-up that can go beyond |
| no movable parts, they can certainly be categorized | | | | the demands of high-speed business or military |
| as SSDs. | | | | environments. |
| But then again, there's more to SSDs than being a | | | | Size Matters |
| non-volatile device. The purpose of this article is to | | | | To be a true plug-in replacement for HDDs, |
| give readers a clearer picture of what an SSD is, its | | | | Flash-based SSDs are manufactured in standard 2.5" |
| usage as well as its difference when pitted against | | | | and 3.5" form factors. 2.5" SSDs are normally used in |
| the predominant data storage device at present - | | | | laptops or notebooks while the 3.5" form factors are |
| the hard disk drive (HDD). More than its non-volatility, | | | | used in desktops, or in JBOD or other SAN/NAS/DAS |
| this article will reveal how much potential SSDs have | | | | configurations. They can often be used to replace |
| in optimizing the performance of the computing | | | | traditional disks in storage arrays or in a server's |
| system. | | | | internal disk bays. Flash-based SSDs certainly fit the |
| SSD Defined | | | | storage needs of most embedded systems that |
| Here are several ways the SSD is defined: | | | | require much smaller form factors. |
| "A solid state disk (SSD) is electrically, mechanically | | | | Reliability |
| and software compatible with a conventional | | | | In terms of reliability, conventional HDDs pale when |
| (magnetic) hard disk or winchester. The difference is | | | | compared to SSDs. The absence of mechanical arms |
| that the storage medium is not magnetic (like a hard | | | | and spinning platters is the reason behind its reliability. |
| disk) or optical (like a CD) but solid state | | | | In demanding environments, SSDs provide the type |
| semiconductor such as battery backed RAM, EPROM | | | | of ruggedness required for mobile applications. Unlike |
| or other electrically erasable RAM-like chip. This | | | | the HDD, SSD's can withstand extreme shock and |
| provides faster access time than a disk, because the | | | | vibration with data integrity and without any danger |
| data can be randomly accessed and does not rely on | | | | of data loss. This feature is very important in |
| a read/write interface head synchronising with a | | | | industrial applications where exposure to highly |
| rotating disk. The SSD also provides greater physical | | | | combustible materials and electromagnetic radiation |
| resilience to physical vibration, shock and extreme | | | | are typical. Their ability to deliver unnerving |
| temperature fluctuations. The only downside is a | | | | performance in extreme conditions also makes SSD |
| higher cost per megabyte of storage."(2) | | | | play a vital role in military operations, be it in defense, |
| "Abbreviated SSD, a solid state disk is a | | | | aerospace or aviation applications. Military applications |
| high-performance plug-and-play storage device that | | | | require, in most cases, an operating temperature |
| contains no moving parts. SSD components include | | | | range of -60°C to +95°C. Shock, vibration, |
| either DRAM or flash memory boards, a memory bus | | | | and temperature ratings of HDDs cannot comply with |
| board, a CPU, and a battery card. Because they | | | | military standards, only SSDs can. |
| contain their own CPUs to manage data storage, | | | | Power Play |
| they are a lot faster (18MBps for SCSI-II and 44 | | | | In addition to speed, reliability and mortality rate being |
| MBps for UltraWide SCSI interfaces) than | | | | positively affected by the SSD's non-volatility, they |
| conventional rotating hard disks ; therefore, they | | | | also consume much less power than traditional HDDs. |
| produce highest possible I/O rates. SSDs are most | | | | No additional power is required to activate the |
| effective for server applications and server systems, | | | | platters or the mechanical arms present in most |
| where I/O response time is crucial. Data stored on | | | | HDDs. Its power consumption is practically only a |
| SSDs should include anything that creates | | | | fraction of a hard disk drive. |
| bottlenecks, such as databases, swap files, library and | | | | Heat Dissipation |
| index files, and authorization and login information."(3) | | | | Along with the lower power consumption, there is |
| For the rest of the article, we will compare the HDDs | | | | also much lesser heat dissipation for systems using |
| and Flash-based SSDs. The latter are the most | | | | Flash-based SSDs as their data storage solution. This |
| popular type of SSDs employed by the military, | | | | is due to the absence of heat generated from the |
| aerospace, industrial and embedded systems | | | | rotating/movable media. This certainly proves to be |
| industries. | | | | the one of the main advantages of Flash-based SSDs |
| Mortality Rate | | | | relative to that of a traditional HDD. With less heat |
| Hard disk failure is a common occurrence in this age | | | | dissipation, it serves as the ideal data storage solution |
| of desktops and notebooks. A lot of horror stories | | | | for mobile systems such as PDAs, notebooks, etc. |
| have been told, passed around and even published | | | | Users can do away with large cooling fans, internal |
| about how valuable data was lost and the agony of | | | | power supply and batteries for large storage arrays |
| trying to retrieve or at least save a portion of the | | | | in storage area networks. |
| crashed hard drive. It is during this time that people | | | | Cost Considerations |
| wonder, why do hard disks fail? | | | | Of course, everything comes with a price. Based on |
| The reason is simple - wear and tear. Just like any | | | | a cost-benefit logic, it is but expected that something |
| good old machine with mechanical components, HDDs | | | | with very impressive features be priced higher than |
| tend to deteriorate over time. HDDs consist of | | | | something that offers fewer benefits. SSDs as being |
| rotating, magnetically coated disks, known as | | | | a bit more pricey than the traditional hard disk drive |
| platters, that are used to store data. This rotating | | | | may be one of the compelling reasons why up to |
| motion of the mechanical arms results in much wear | | | | now it hasn't gained as much popularity as it should |
| and tear after long periods of use. The operational | | | | be getting with all its brilliant functions. |
| lifespan of a computer HDD is over three years.(4) | | | | While the use of SSDs today have mostly been |
| A Flash-based SSD is different. Although the most | | | | limited to industrial and military implications, enterprise |
| common Flash chips have around 300,000 write | | | | are now looking closely at SSDs for implementing |
| cycles, the best Flash chips are rated at 1,000,000 | | | | tiered storage and optimizing their storage |
| write cycles per block. On top of that, Flash SSD | | | | architectures. |
| manufacturers employ different ways to increase the | | | | To quote from the Solid State Disks Buyers Guide |
| longevity of the drives. In some cases, they use a | | | | published by storagesearch.com, "In fact the SSD is |
| "balancing" algorithm to monitor the number of times | | | | replacing servers and software licenses. SSDs can be |
| each disk block has been written, which greatly | | | | used either to speed up the response time of |
| extends the operational lifespan of the drive. | | | | existing applications as an alternative to buying more |
| Furthermore, these manufacturers also designed | | | | servers, or to reduce the number of servers and |
| special "wear-leveling" algorithms where once a | | | | software licenses deployed. The economics can be |
| certain percentage threshold for a given block is | | | | compellingly in favor of an SSD deployment". The |
| reached, the SSD will swap the data in that block | | | | industry is also expecting more breakthroughs as |
| with the data in another block that has exhibited a | | | | higher memory capacities and faster performance are |
| "read-only-like" characteristic in the background. This | | | | now being produced for a wider array of choices fit |
| reduces performance lag and avoids further wearing | | | | for any mission-critical application. |
| off of the blocks and thrashing of the disk. Even with | | | | Analysts foresee a rapidly closing gap between HDD |
| usage patterns of writing/reading gigabytes per day, | | | | and flash SSD pricing (see related article "Are Flash |
| a Flash-based SSD should last several years, | | | | Solid-State Disks Ready for the Enterprise"(5) ). This |
| depending on its capacity. Add to that the inclusion of | | | | vision is also bolstered by a recent announcement(6) |
| a DRAM cache in the disk architecture that further | | | | of electronic giant Samsung that they will invest |
| enhances its operational capabilities as well as lifespan. | | | | heavily in improving their flash and DRAM production |
| Speeding Up | | | | lines and flash SSD equipped laptops. Only time will tell |
| With the very fast paced lifestyle these days, most | | | | if we will witness widespread commercial adoption of |
| businesses are time-bound and cannot afford a | | | | SSDs. |
| slowing down in their transactions. This makes speed | | | | |