SOLID STATE HARD DISKS Presented by Dean Casey

Solid State Hard Disks The solid state hard disk uses a solid state memory to store its data. The solid state hard disk is also called SSD or Ram-drive. The memory used in SSD is usually Static Random Access Memory (SRAM) or Dynamic random access memory (DRAM) instead of flash memory.

History Of The Solid State Hard Disks The first SSD also known as magnetic core memory, forresstor memory, ferrite core memory are the early forms of random access memory chips which was created by Fredrick Viehe in 1947 but was discontinued when they introduced drum memory which was cheaper. In 1970 and 1980 SSD were implemented in semiconductor memory for the early supercomputers, it was not widely used due to it being too expensive. The first modern day SSD was developed by Storage Trek and in 1980 Santa Clara Systems introduced Bat Ram an array 1 megabit dual in line RAM Chips and custom controller card. In 1983 sharp-5000 introduced 128 kilo byte solid state storage state which contained bubble memory and in 1995 M- system introduced flash based SSD which is a commercial success.

Solid State Hard Disk Flash Drives The most common manufactured hard disks are solid state hard disks that are non- volatile flash memory for the consumer market. These Solid state hard disks use flash memory also called flash drives. The standard solid state hard disks are 1.8,2.5 and 3.5 inch. Flash SSD allow to retain memory on the hard disk even when there is a Sudden power outage. The Flash SSD are slower than DRAM SSD but is quicker in Seek times than the standard mechanical hard disks.

Single Level cell Flash Memory & Multi level cell Flash Memory Multi level cell flash memory is able to store more information than single level cell flash memory and is cheaper to manufacture one of the draw backs of multi level cell flash memory is more errors reading and writing. Single level flash memory has the advantages of faster write speeds, lower power consummation and higher cell endurance than multi level cell flash memory the drawback is that it cant contain as much information per cell and cost more to manufacture per megabyte.

Advantages OF Solid State Hard Disk Faster startup that it has no spin-up required Faster random access memory because there is no read and write head Low read Latency for SSD Constant read performance File fragmentation has only small effect on SSD Silent operation Low capacity SSD have a much lower power consumption and generates little heat when using SSD High mechanical reliability Able to endure extreme shock, high altitude, vibration and extreme temperature Failures while writing and erasing data

DRAM Solid State Hard Disks DRAM SSD are based on DRAM that is volatile It allows these hard disks to have ultra fast data access at 0.01 milliseconds, which allows applications to run very fast. Dram SSD usually have a internal battery or an external AC or DC adapter also a backup system for storage to ensure that data is not lost when there is power outage.

Disadvantages OF Solid State Hard Disks SSD as of mid-2008 SSD are more expensive per gigabyte than standard The capacity of SSD is usually lower than standard Hard Drives SSD currently have slower write performance than their read performance The low storage destiny hard disk can store more data per unit than SSD Flash memory cells have limited lifetime 1,000 to 10,000 write cycles for Multi level cells and 100,000 write cycles for single level cells Performance with SSD degrade with each use SATA based SSD are usually write at slower speeds DRAM SSD require more power than Hard disks

Solid State Hard Disk Availability The availability of SSD has been marketed to the military and specialized markets since the As of 2008 the manufactures have been able to create fast and energy efficient drives that cost about $350 shipped to the computer manufactures. USB flash drives are also available, from $10 to $100 depending on the capacity of the drive. As of 2008 SSD hard disks are being implemented into laptops from the Mac book and Mac book pro lines, EEPC Subnet books to Dell and other major computer companies.

Performance & Quality OF Solid State Hard Disks The quality and the performances of SSD market was reviewed in January 2009 by Toms hardware. Few of the SSD showed acceptable input and output performance although they did not perform well in other tests many small writes on some SSD can lead to the system to freeze for periods up to 1 second at a time. Toms hardware overall concluded that none of the Intel SSD were really impressive except the Intel SSD

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