《SSD相关技术研究》PPT课件

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1、SSD相关技术研究武汉大学计算机学院系统结构研究所何水兵许先斌杨元华2010.11.25主要内容SSD简介Flash-basedSSD特点SSD内部结构SSD关键技术SSD设计方案SSD相关项目SSD工业界厂商实验平台参考资料1SSD(SolidStateDisk)简介基于半导体的存储设备1.1SSD分类1.2SSD应用领域个人计算机BIOS存储嵌入式系统的标准存储器在某些笔记本电脑中代替磁盘作为外存储器企业级存储的高端存储阵列1.3数据访问时间1.4随机I/O性能1.5能耗1.6性能和价格2Flash-basedSSD特点2.1SSD优点Reliabilityinportab

2、leenvironmentsandnonoiseNomovingpartsFasterstartupDoesnotneedspinupExtremelylowreadlatencyNoseektime(25usperpage/4KB)DeterministicreadperformanceTheperformancedoesnotdependsonthelocationofdata2.2SSD缺点Costsignificantlymoreperunitcapacity3$/GBvs.0.15$/GBLimitedwriteerasetime100000writesforSLC(

3、MLCisevenfewer)highendurancecellsmayhavean1-5millionButsomefilesstillneedmoreWeaverleavingtospreadwritesalloverthediskSlowerwritespeedsbecauseoftheeraseblocksarebecominglargerandlarger(1.5mspererase)ForlowcapacityflashSSDs,lowpowerconsumptionandheatproductionwheninactiveuse.HighcapacitySSDsm

4、ayhavesignificanthigherpowerrequirements2.3典型读写速率硬盘读性能2.4Flash重写问题3SSD内部结构SSD逻辑组件3.1Flash内存FlashmemoryAnon-volatilesemiconductormemorydeviceKeyfeature:Tooverwritedata,thememorycellshouldbeerasedfirst.KindsofflashmemoryNORIntroducedbyIntelin1988Randomlyaccessdata,likeacomputer’smainmemoryUsef

5、orexecutingprogramcodeNANDIntroducedbyToshibain1989Smalleranddenser.→NANDisbetteratstoringdata.FastereraseandwritetimeNORNANDNANDvs.NORProsofNANDProsofNORConsofNANDConsofNORForMassStorageForCodeStorage1.Smallercellsize2.Limitedbadblocksallowed3.Fastwriting4.Lowerpowerconsumption1.Fastrandom(

6、read)access1.Slowrandom(read)access1.Largercellsize2.Nobadblocksareallowed3.Slowwriting4.HigherpowerconsumptionWefocusontheNANDflashmemory!NANDFlashOrganizationofNANDflashmemorySmall-blockflashmemoryEachpageis(512+16)byteslong32pagesineachblockLarge-blockflashmemoryEachpageis(2048+64)byteslo

7、ng64pagesineachblockPage0Block1Page1Pagem-1Blockn-1Block051216204864Pagelayoutforsmall-blockflashmemoryPagelayoutforlarge-blockflashmemoryMainAreaSpareAreachipNANDFlashPrimitiveoperationsofNANDflashmemoryReadpage(chip#,block#,page#)~20usWrite(progr