What is an ssd (with pictures) gas tax


A solid-state drive (SSD), also called a flash drive, is type of hard drive. Though the architecture of an SSD is quite different from traditional hard drives, the name is carried over. An SSD utilizes a special kind of memory chip with erasable, writeable cells that can hold data even when powered off. It might help to think of an SSD as the larger cousin of the memory stick.

Like standard drives, an SSD utilizes a special area for cache memory. Cache memory serves the function of increasing processing speeds by holding data that is needed repeatedly. With the data close at hand in the cache, it does not need to be fetched from the main storage area each time it’s called.

Some SSDs use cache that is volatile, as in synchronous dynamic random access memory (SDRAM), while others use non-volatile cache. The former requires a power source to retain data, just like computer RAM. The latter type retains data even without power.

An SSD has many advantages over a traditional drive. Seek time is decreased significantly, making the SSD very fast. Being solid-state, the drive has no moving parts to malfunction, and does not generate significant heat. It is also lighter than a standard drive, more power efficient, and completely silent. Finally, the SSD is more durable. If dropped or banged it isn’t as likely to be damaged.

can run 100 feet, and 1200 men can each run an inch far, far faster than that poor horse can run that 100 feet. Each chip may be slower than a spinning magnetic platter, but eight, sixteen, or thirty-two all accessing pieces of the desired data at the same time are cumulatively far faster than even the fastest HDDs can manage. As an example, the OCZ Agility 2 that I have as my system drive can read/write at 285/275 MB/s, while the Western Digital Scorpio Black that it replaced, one of if not the fastest 2.5" hard drive available at the time of this posting, is rated at 108/108. HDDs also suffer very poor latency due to the required physical movement of the heads to the tracks where the data is, while where on the chips in an SSD the data is is irrelevant and their latency is thousands of times lower than HDDs. Thousands. Taken all together this means that an SSD can access, read, and write data far faster than an HDD. They also shine in random IOPS (input/output per second), which is the kinds of very small but fast data reads and writes that databases and other applications perform on servers and operating systems often perform on home computers (most often as swap files), where they can be dozens to hundreds of times faster than HDDs. SSDs are also silent, more physically durable (since they have no moving parts, and are thus more resistant to damage from impacts), use much less power, and operate at a much lower temperature than HDDs, saving you on your electric bill and making your computer quieter and cooler at the same time.

The most commonly stated, and misunderstood, fundamental drawback to SSDs is their allegedly poor longevity. It is true that each cell can only be written to a certain number of times–depending on the type and quality of chip it can vary from 10,000 to hundreds of thousands of writes. However, thanks partly to ever increasing quality of flash chips and partly to ever improving wear-leveling technology in the controller chips this is not the deal breaker the uninformed make it out to be. "Wear leveling" is the catchall term for a variety of techniques that different SSD controller makers use to spread the writes evenly across all cells, so that no cell or group of cells wears out quickly but all do gradually wear out together, and as individual cells do begin to wear out it is recognized by the controller and the data on them is replaced with data that has been only read in the past, to reduce the chance for further writes. In real life this amounts to good consumer grade SSDs having longer MTBFs (mean times between failure, the industry term for expected average lifespan) than HDDs. That’s right, kids, LONGER expected lifespans. My OCZ Agility 2, for instance, has an MTBF of 2 million hours, while the Western Digital Scorpio Black it replaced has an MTBF of 1 million hours.

To sum up, while you do have to do some research to find which SSDs are worth the much higher cost compared to HDDs (I recommend Intel’s X-25M or OCZ’s Agility 2 or Vertex 2 as of this posting), they read faster, write faster, access faster, use less power, are quieter, are more durable, and last longer than hard drives. The only two real drawbacks are cost and size. SSDs are much more expensive than HDDs, and tend to be much smaller to keep costs down. I recommend using both. Use an SSD for the system drive, with the operating system and applications that can benefit from the performance boost of an SSD, and a large HDD for media storage, which doesn’t see much of a benefit if any. In my personal system I use a 50 GB SSD for the operating system and applications and 4 1 TB drives in a Drobo connected by Firewire 800 for media storage, a 250 GB HDD in a USB2 enclosure for system drive backup, a 1 TB HDD in another USB2 enclosure for additional storage, and a 16 GB flash drive for file transfers between non-networked systems.