The first chapter SSD review
SSD (Solid State Drive) SSDs, a semiconductor flash memory (NAND Flash) storage device as a medium.
Mainly composed of: main memory, cache chip DRAM, PCB (power chips, resistors, capacitors, etc.), an interface (SATA, SAS, PCIe, etc.). Subject to PCB.
Storage media: optical storage media:. DVD, CD and other optical media, such as CD-ROM by the host to read or write.
2. The magnetic storage media: HDD.
The semiconductor chip storage medium: SSD. Mainly: Flash, 3DX Point, MRAM, RRAM and so on.
SSD HDD relative advantages: good performance: can exceed several times or even hundreds of times, especially on random reads and writes.
Low power consumption: HDD is 6 ~ 8W, SATA SSD is 5W, SSD standby can be reduced mW.
Seismic drop resistance: no mechanical parts inside SSD, HDD head and the magnetic sheet while transmitting the collision, will have physical damage.
No noise: Because the SSD does not require HDD motor.
Small: HDD general 3.5 / 2.5 inch. In addition to SSD can be attached to the motherboard M.2, even 16mm * 30mm chip level.
SSD of three modules: front-end interface and associated protocol module. FTL intermediate layer (comprising: bad block management, address translation, garbage collection, wear leveling). Flash memory module and the rear end of the communication.
The front end and the SSD host communication, receives data and commands, and returns status data to the host. The use of: SATA (ATA Protocol), SAS (SCSI protocol), PCIe (NVMe Protocol) interface with the host connection.
SSD of several core parameters:
1. Basic information: Capacity, media information, the appearance of size, weight, temperature, vibration reliability, certification, encryption.
2. Performance: continuous read and write bandwidth IOPS random read and write, delay, maximum delay.
3. Data reliability and life: reliability, longevity.
4. Power: Power Management, Active Power and Idle Power.
5. Compatibility: Compliance, Compatibility.
Basic Information:
1. Capacity: 128GB for binary and decimal, binary decimal will be more than 7%. Generally referred to as raw capacity binary, decimal user capacity, 7% more space for managing and storing internal data.
2. The media information: such as life, erasing and reading time, temperature and the like. Table 1-6.
SLC memory unit 1bit speed, long life, but the price is three times the MLC. MLC storage unit 2bit, speed in general, life in general, prices in general. TLC storage unit 3bit, slow, short life, the price is cheap.
3. Dimensions: The 2.5-inch, 3.5-inch, M.2, PCIe, mSATA, U.2 standards.
4. Temperature: Operating temperature 0 ~ 7 °, boot. Non-working temperature of -50 ~ 90 °, transportation.
Performance analysis:
1. performance: IOPS: IO unit processing times. Throughput: the processing amount of data per second. Response time: time delay, i.e. the time to issue a receipt.
2. Access mode: random and sequential, random order LBA is continuous discontinuous. Block Size block size, generally random testing 4k, test sequence 512k. Mixed read and write commands, read and write tests in accordance with the mixing ratio.
3. Delay indicators: average delay refers to the total time divided by the total command. The maximum delay is the longest response time, directly affect the user experience.
4. Quality of Service: Quality of Service, QoS. Distribution by recording 2 9 (99%) and five nines (99.999%) view.
5. Performance data at a glance: Full disk space and disk write speed of the SSD is a big difference (triggers garbage collection). Since the cover for the HDD write, therefore plateful and write disk space or less.