# VRPM > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/VRPM > Markdown URL: https://mediated.wiki/source/VRPM.md > Source: https://en.wikipedia.org/wiki/VRPM > Source revision: 1239369030 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{Tone|date=April 2010}} {{lowercase}} '''vRPM''', or '''virtual Revolutions Per Minute''', was a term for a synthetic [measurement of performance](/source/benchmark_(computing)) introduced by [SanDisk](/source/SanDisk) for [solid state drive (SSD)](/source/Solid-state_drive) storage devices inside client [PCs](/source/personal_computer). vRPM was created to give users a metric to compare SSD performance to the [hard disk drive (HDD)](/source/Hard_disk_drive) and other SSDs. vRPM calculates how fast one would have to spin a virtual HDD to achieve the equivalent performance of an SSD in a client PC. It uses RPM ([revolutions per minute](/source/revolutions_per_minute)), a [''de facto'' industry standard](/source/de_facto_standard) to measure the performance of the HDD inside PCs.{{Citation needed|date=September 2022}} ==Comparing SSD vs. HDD input/output operation== The performance of a storage device can be quantified as the number of [input/output](/source/input%2Foutput) operations Per Second (IOPS) it achieves. HDD IOPS is proportional to RPM. When a system requests to read or write data randomly from/to a HDD, [seek time](/source/seek_time) and [rotational latency](/source/rotational_latency) are two HDD activities that significantly reduce HDD IOPS. Seek time is the time it takes to move the HDD head to the correct [cylinder](/source/Cylinder_(disk_drive)) to begin to receive data. Rotational latency is the time it takes to rotate the HDD platter beneath the head so that the data can be read/written. Rotational latency varies based on the RPM of the HDD.{{Citation needed|date=September 2022}} [NAND flash](/source/NAND_flash) is used as the [non-volatile memory](/source/non-volatile_memory) inside SSDs. It has faster random read than random write performance, since its write performance is delayed by the need to perform [garbage collection](/source/Garbage_collection_(computer_science)) to free space for writing. However, since NAND flash has no moving parts, the SSD achieves much higher IOPS than a HDD. For the client PC usage model with approximately a 50:50 read/write ratio, a PC IOPS number can be calculated as follows: :PC IOPS (mean)=1/[0.5/SSD IOPS (Iwrite)] + [0.5/SSD IOPS (Iread)] Using this equation, the results for client SSD PC performance are as follows: * 2006–2007 SSD generation: 5,000 Read IOPS; 10 Write IOPS; 20 PC IOPS * 2008 SSD generation: 10,000 Read IOPS; 100 Write IOPS; 200 PC IOPS * 2009 (estimated) SSD generation: 25,000 Read IOPS; 400 Write IOPS; 785 PC IOPS ==Converting SSD IOPS rates into vRPM== The vRPM performance of an SSD can be calculated as follows: :vRPM=50/[0.5/SSD IOPS (Iwrite)] + [0.5/SSD IOPS (Iread)] where: * SSD IOPS (IWrite) is the sustained (to the SSD media) 4KB random write rate, Queue Depth=4 * SSD IOPS (IRead) is the sustained (to the SSD media) 4KB random read rate, Queue Depth=4 * 50 is the product factor in the calculation Using this calculation, SSD vRPM rates can be shown to be significantly better than HDD RPM rates, particularly in later generation SSDs: * 2006–2007 SSD generation: 5,000 Read IOPS; 10 Write IOPS; 20 PC IOPS; 1,000 vRPM * 2008 SSD generation: 10,000 Read IOPS; 100 Write IOPS; 200 PC IOPS; 10,000 vRPM * 2009 (estimated) SSD generation: 25,000 Read IOPS; 400 Write IOPS; 785 PC IOPS; 40,000 vRPM * 2011 SSD generation: 35,000 Read IOPS; 14,000 Write IOPS; 24,500 PC IOPS; 1,225,000 vRPM ==vRPM adoption in industry== Despite its early objectives, vRPM has not become broadly supported in the industry and no longer appears on SanDisk's SSD website.{{cite web|url=http://www.sandisk.com/business-solutions/ssd/technical-expertise--metrics|title=Technical Expertise and Metrics|publisher=SanDisk Corporation|date=September 27, 2011|accessdate=2011-09-27|url-status=dead|archive-date=2011-09-11|archive-url=https://web.archive.org/web/20110911080153/http://www.sandisk.com/business-solutions/ssd/technical-expertise--metrics}} ==See also== * [Solid-state drive](/source/Solid-state_drive) * [Hard disk drive](/source/Hard_disk_drive) * [Input/Output](/source/Input%2FOutput) ==References== {{reflist}} * {{cite web|url=http://www.marketwatch.com/news/story/SanDisk-Introduces-ExtremeFFS-New-Flash/story.aspx?guid={6096177E-1745-4BFC-9046-AE82E62ABC1F}|title=SanDisk introduces ExtremeFFS — New flash management system for improving SSD performance and reliability|publisher=[MarketWatch](/source/MarketWatch)|date=November 7, 2008|accessdate=2008-11-07|url-status=dead}} ==External links== * [https://web.archive.org/web/20160303191424/https://www.sandisk.com/Assets/File/pdf/oem/vRPM%20White%20Note.pdf vRPM White Note] by SanDisk Category:Computer storage devices --- Adapted from the Wikipedia article [VRPM](https://en.wikipedia.org/wiki/VRPM) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/VRPM?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.