Advantages
* Faster start-up, as no spin-up is required (RAM & Flash).
* Typically, fast random access for reading, as there is no read/write head to move (RAM & Flash).[13]
* Extremely low read latency times, as SSD seek-times are orders of magnitude lower than the best current hard disk drives.[14] (RAM) In applications where hard disk seeks are the limiting factor, this results in faster boot and application launch times (see Amdahl's law)[15] (RAM & Flash).
* Extremely fast write (RAM, nearly the same for best modern flash).
* No noise: a lack of moving parts makes SSDs completely silent, unless, as in the case of some high-end and high-capacity models, they have cooling fans attached (RAM & Flash).
* For low-capacity flash SSDs, low power consumption and heat production when in active use, although high-end SSDs and DRAM-based SSDs may have significantly higher power requirements (Flash).
* High mechanical reliability, as the lack of moving parts almost eliminates the risk of mechanical failure (RAM & Flash).
o Ability to endure extreme shock, high altitude, vibration and extremes of temperature: once again because there are no moving parts.[16] This makes SSDs useful for laptops, mobile computers, and devices that operate in extreme conditions (Flash).[15]
* Larger range of operating temperatures. Typical hard drives have an operating range of 5-55 degrees C. Most flash drives can operate at 70 degrees, and some industrial grade drives can operate over an even wider temperature range.[17]
* Relatively deterministic read performance:[18] unlike hard disk drives, performance of SSDs is almost constant and deterministic across the entire storage. This is because the seek time is almost constant and does not depend on the physical location of the data, and so, file fragmentation has almost no impact on read performance.
* For low-capacity SSDs, lower weight and size: although size and weight per unit storage are still better for traditional hard drives, and microdrives allow up to 20 GB storage in a CompactFlash 42.8×36.4×5 mm (1.7×1.4×.2 in) form-factor. Up to 256 GB, SSDs are currently lighter than hard drives of the same capacity.[16]
* When failures occur, they tend to occur either 'on write', or 'on erase', rather than 'on read'. With traditional HDDs, failure tends to occur 'on read'. If the drive detects failure on write, data can be written to a new cell without data loss occuring. If a drive fails on read, then data is usually lost permanently. [19]
[edit] Disadvantages
* Cost: As of mid-2008, SSD prices are still considerably higher per gigabyte than are comparable conventional hard drives: consumer grade drives are typically US$2.00 to US$3.45 per GB[9][20] for flash drives and over US$80.00 per GB for RAM-based compared to about US$0.38 per gigabyte for hard drives[9].
* Capacity: Currently far lower than that of conventional hard drives (Flash SSD capacity is predicted to increase rapidly, with experimental drives of 1 TB,[21][22], hard drive capacity also continues to expand, and hard drives are likely to maintain their capacity edge for some time.)[23]
* DRAM based SSDs have a higher vulnerability to abrupt power loss.
* Limited write (erase) cycles: Flash-memory cells will often wear out after 1,000 to 10,000 write cycles for MLC, and up to 100,000 write cycles for SLC[9], while high endurance cells may have an endurance of 1–5 million write cycles (many log files, file allocation tables, and other commonly used parts of the file system exceed this over the lifetime of a computer).[24] Special file systems or firmware designs can mitigate this problem by spreading writes over the entire device (so-called wear levelling), rather than rewriting files in place.[25] In 2008 wear levelling was just beginning to be incorporated into consumer level devices.[9] However, effective write cycles can be much less, because when a write request is made to a particular memory block, all data in the block is overwritten even when only part of the memory is altered. The write amplification, as referred by Intel, can be reduced using write memory buffer.[26] In combination with wear leveling, over-provisioning SSD flash drives with spared memory capacity also delays the loss of user-accessible memory capacity. NAND memory can be negatively impacted by read and program (write) disturbs arising from over accessing a particular NAND location. This overuse of NAND locations causes bits within the NAND block to erroneously change values. Wear leveling, by redirecting SSD writes to lesser-used NAND locations, thus reduces the potential for program or write disturbs.[27] An example for the lifetime of SSD is explained in detail in this wiki.[dubious – discuss] SSDs based on DRAM, however, do not suffer from this problem.
* Slower write speeds: As erase blocks on flash-based SSDs generally are quite large (e.g. 0.5 - 1 megabyte)[9], they are far slower than conventional disks during small writes and can suffer from write fragmentation,[28] and in some cases for sequential writes.[15] SSDs based on DRAM do not suffer from this problem. It should also be noted the smaller the blocks being written the more pronounced the problem becomes.
* Lower storage density: Hard disks can store more data per unit volume than DRAM or flash SSDs, except for very low capacity/small devices.
* RAM based SSD require more power than hard disks, when operating; and they still use power when the computer is turned off, while hard disks do not.[29]
