AsawariKhedkar_SSD_HDD_Comparison
- 1. STORAGE DEVICES IN VEHICLES; AN SSD APPROACH BY ASAWARI KHEDKAR [email protected] Storage Devices in Vehicles; an SSD Approach. By Asawari Khedkar Table of Contents Overview.....................................................................................................................................................................2 Need for Storage Devices in Vehicles.........................................................................................................................2 Understanding the Technology behind SSDs .............................................................................................................2 Performance Parameters ...........................................................................................................................................2 Durability, Shock and Vibration .........................................................................................................................2 Data Access Time and Latency.........................................................................................................................3 Input / Output Operations per Second..............................................................................................................4 Power Consumption............................................................................................................................................5 Performance...............................................................................................................................................................6 Summary.....................................................................................................................................................................6 Comparison Chart........................................................................................................Error! Bookmark not defined. References..................................................................................................................................................................7 Figure 1 Comparison between Read Latency Values of HDD and SSD......................................................................4 Figure 2 IOPS Values of SSD vs HDD ..........................................................................................................................4 Figure 3 Read Throughput of SSD vs HDD .................................................................................................................5 Figure 4 Power Usage of SSDs vs HDDs.....................................................................................................................5 Table 1 Shock and Temperature Comparison ...........................................................................................................3 Table 2 Data Access Time and Speed Comparison...................................................................................................3 Table 3 Benchmark Results Comparison: HDD vs. SSD..............................................................................................6 Table 4 Comparison between SSD and HDD .............................................................................................................6 pg. 1
- 2. STORAGE DEVICES IN VEHICLES; AN SSD APPROACH BY ASAWARI KHEDKAR [email protected] Overview Convergence of automotive, semiconductor and consumer technologies is transforming the automotive industry. Vehicles manufactured today are in many ways rolling computers with features like navigation and infotainment. Need for Storage Devices in Vehicles Vehicles have advanced technological features like 3D mapping, traffic reporting, multimedia, satellite radio, voice recognition, and interaction with the driver’s phone. These applications are handled via an on-board computer system. Multiple sensors are placed at strategic locations, which feed data to the onboard computer. As an example, the sensor placed on vehicle’s wheels, measures tire pressure and feeds the data to the onboard computer. The on-board computer requires a storage media to store this information. The on-board computer system requires a boot up process which in turn needs a storage media to deliver data to the computer. This white paper describes the breakthrough performance advantages of using Solid State Drives (SSDs) as storage, over traditional Hard Disk Drives (HDDs) used in current automobiles. Potential benefits of using SSDs are discussed and comparisons are made against HDDs. The data is based on various organization’s published specifications. The metrics used in this paper are associated with device performance, reliability, and environmental factors. Understanding the Technology behind SSDs The key components of an SSD (Solid State Drives) are NAND flash non-volatile memory and flash controller. The NAND flash non-volatile memory stores data and flash controller manages the communication of stored data with a computer system or other electronic device. When the computer system needs to read data from or write data to the NAND flash memory, it will communicate with the flash controller. The flash controller maps the memory cells and creates a directory structure. The directory structure stores the physical location mapping of the memory locations to the logical sectors of the controller. On a read or write, the controller looks up the data from the directory and sends it to the requesting computer system. Performance Parameters This white paper describes and compares the following parameters related to SSDs and HDDs; Durability, Shock and Vibration, Data Access Time and Latency, Input / Output Operations per Second, Throughput, and Power Consumption. Durability, Shock and Vibration SSDs (Solid State Drives) have high resistance to shock, vibration and extended temperatures. The SSDs are more durable in moisture conditions than HDDs (Hard Disk Drives). When used in music systems the HDDs need to be mounted at a correct axis. An off road driving vehicle may have up to ±4g of acceleration in random directions which the spinning HDD cannot tolerate. The HDD drive head will scratch and potentially damage a music disk if the vehicle drives at a non-horizontal axis. The SSD does not have any axis and can be mounted at any angle. Since it does not have any moving parts, the SSD can withstand shocks and vibrations. pg. 2
- 3. STORAGE DEVICES IN VEHICLES; AN SSD APPROACH BY ASAWARI KHEDKAR [email protected] Table 1 Shock and Temperature Comparison Parameters SSD HDD Shock 1500 G 300 G Operating Temperatures 0 deg C - 100 deg C 0 - 60 deg C In addition to the enhanced vibration resistance, expanded operating temperatures and humidity ranges, the storage devices have to address the needs of the on-board computer, such as lower access times, lower latencies and enhanced performance. Data Access Time and Latency One of the main reasons SSD (Solid State Drives) outperforms HDD (Hard Disk Drives) is SSD’s incredibly fast data access time. Data access time is the delay between the request and the completion of a read or write operation. It has a random data access time of 0.1 millisecond or less, whereas the mainstream 2.5” HDD takes 10~12 milliseconds to complete a read or write operation. As seen in Table 2, SSDs are 100 times faster than HDDs in accessing data. The SSD controller communicates via fast ‘Flash Transaction Layer’ controller with the physical memory (NAND flash), which accelerates the data retrieval time. HDDs are affected by fragmentation and must wait for spindles, motor heads, and arms to physically locate data locations. Read latency of SSDs is low. Read Latency is the time the storage device takes, to start any IO task. The smaller the latency time the better. SSDs deliver consistent lower latencies as they have controllers and NAND Flash based integrated circuits and do not rely on spinning platters like HDDs to access data. Read latency of HDD is not consistent and may change for every read operation. The read time is different for every read and depends on the location of the data on the HDD disk. Table 2 Data Access Time and Speed Comparison Category SSD (540 GB) HDD (500 GB, 720 rpm) Difference Media NAND Flash Magnetic Platters x3~ 8 / 2 ~ 5 Data Access Time (ms) 0.1 10 ~ 12 x100 ~ 120 Sequential R/W Speed (MB/s) 540 / 330 60 / 160 (*140 / 70) x 3~8 / 2~5 Random R/W Speed (IOPS) 98,000 / 70,000 450/400 217 / 175 Sustained Read 90+ MB/s 70MB/s ~20+ MB/s pg. 3
- 4. STORAGE DEVICES IN VEHICLES; AN SSD APPROACH BY ASAWARI KHEDKAR [email protected] Read Latency Low High Figure 1 Comparison between Read Latency Values of HDD and SSD Input / Output Operations per Second The time taken to perform a task such as accessing a page (large chunk of data) is measured in Input / Output Operations per Second. The greater the number of IOPS the better the performance. Large amount of data is stored in a unit called “page”. The page belongs to a group of pages collectively called “blocks” on an SSD (Solid State Drives) and HDD (Hard Disk Drives). The SSDs have better IOPS than HDDs as the SSD controller communicates via fast ‘Flash Transaction Layer’ with the physical memory location (NAND flash). HDDs rely on motor heads, and arms to physically locate data and deliver it to the requesting device. The storage IOPS (input/output operations per second) from HDDs has not been able to keep up with the integrated circuits in the SSDs. The chart below (Figure 2) shows the IOPS values of HDDs and SSDs. Current SSDs achieve 100x - 1,000x higher IOPS than HDDs. Figure 2 IOPS Values of SSD vs HDD 0 1000 2000 3000 4000 5000 6000 SSD HDD Typical Read Latency (us) SSD HDD 0 1000 2000 3000 4000 5000 6000 SSD HDD Input / Output Operations per Second (IOPS) SSD HDD pg. 4
- 5. STORAGE DEVICES IN VEHICLES; AN SSD APPROACH BY ASAWARI KHEDKAR [email protected] Throughput The speed at which data is transferred out of or into the storage device, is called throughput and is measured in bytes per second, commonly kilobytes or megabytes per second. The greater the throughput the better the performance. SSDs (Solid State Drives) have a higher throughput than the HDDs (Hard Disk Drives). Throughput is measured at steady state by applying the preconditioning methodology and 5 Round Steady State Determination formula. The chart in figure 3 compares the typical read throughputs of SSDs vs HDDs. Figure 3 Read Throughput of SSD vs HDD Power Consumption SSDs (Solid State Drives) consume less power than HDDs (Hard Disk Drives). With no moving parts the SSDs have lower heat output. The storage disk cabinet cooling effort is hence, significantly reduced. As shown in the Figure 4, SSDs consume less power, (about 1.8W), than HDDs (about 7 W) at the peak load. Their energy efficiency can deliver less power strain on the system and thus a cooler environment. Figure 4 below shows the comparison of power consumption values at peak loads and at idle times. Figure 4 Power Usage of SSDs vs HDDs 0 200 400 600 SSD HDD Typical Read Throughput (MB / Sec) SSD HDD 0 2 4 6 8 SSD Load SSD Idle HDD Load HDD Idle Power Usage in Watts (W) SSD Load SSD Idle HDD Load HDD Idle pg. 5
- 6. STORAGE DEVICES IN VEHICLES; AN SSD APPROACH BY ASAWARI KHEDKAR [email protected] Performance The four main factors discussed above, data access times, latency, IOPS and throughput truly indicate the performance of a storage device. High performance is critical in vehicles as a large portion of the storage accesses are time critical and extremely essential for passenger safety. The benchmark results based on industry-standard PCMark test measurements are shown below. Table 3 Benchmark Results Comparison: HDD vs. SSD Benchmark HDD SSD PCMARK Seagate 320GB Intel 80GB 4602 31443 PCMARK Western Digital 6G 1TB Micron 6G 256GB 5580 28179 Summary Next generation automobiles are taking advantage of SSDs (Solid State Drives) to eliminate the shortcomings of HDDs (Hard Disk Drives). It is extremely beneficial to adopt SSDs to maximize the input output operations per second while efficiently minimizing the application latency. The next generation PCIe - NAND Controller based SSDs have added gains to maximize application processing performance. The ability of SSDs to withstand heat, irregular axis alignment is an added benefit. The chart shown in Table 4 summarizes the analysis of this white paper, and emphasizes the benefits of a Solid State Drive (SSD) against a Hard Disk Drive (HDD). Comparison Table 4 Comparison between SSD and HDD Feature SSD HDD Mechanism Solid NAND Flash Magnetic rotating platters Speed 80 - 250 MB/s 65 - 85 MB/s Average Seek Time 0 < 10ms pg. 6
- 7. STORAGE DEVICES IN VEHICLES; AN SSD APPROACH BY ASAWARI KHEDKAR [email protected] Noise None Noisy Data Access Time 0.1 12 Read Latency Low High Power Consumption 2W> 10W. Generates more Heat Weigh Light Heavy Endurance MTBF > 2,000,000 hours MTBF < 7000,000 Temperature -40 ~ 100 0 ~ 60 Reliability Anti – shock Non-shock resistant Shock Vibration Resistance Excellent Poor References 1. Alcorn, Paul. "Micron First to Bring Automotive-grade M500IT SSDs into Your Vehicle." www.Tweaktown.com. November 3, 2014. Accessed July 30, 2015. 2. Kung, Shawn. "Native PCIe SSD Controllers A Next-Generation Enterprise Architecture For Scalable I/O Performance." www.Marvell.com. 2012. Accessed July 30, 2015. 3. "Benefits of SSD vs. HDD." www.amplicon.com. Accessed July 30, 2015. 4. Chan, Eric Hong. "Samsung Solid State Drive." www.samsung.com. Accessed July 29, 2015. 5. Janukowicz, Jeff, and David Reinsel. "The Total Cost of Ownership for an SSD-Enabled PC." www.sandisk.com. July 1, 2011. Accessed July 29, 2015. 6. ."SSD Power Savings Render Significant Reduction to TCO." October 25, 2010. Accessed July 29, 2015. 7. Vamsee Kasavajhala. "SSD vs HDD Price and Performance Study, a Dell technical white paper." Dell PowerVault Technical Marketing. 11 May 2011. Accessed July 29, 2015. 8. Geoff Gasior . "SSD prices in steady, substantial decline: A look at the cost of the current generation". The Tech Report. June 21, 2012. Accessed July 29, 2015. pg. 7