ZB+-tree：一种ZNSSSD感知的新型索引结构刘扬金培权（中国科学技术大学计算机科学与技术学院合肥230026）（中国科学院电磁空间信息重点实验室合肥230026）（liuyang32@mail.ustc.edu.cn）ZB+-tree:ANovelZNSSSD-AwareIndexStructureLiuYangandJinPeiquan（SchoolofComputerScienceandTechnology,UniversityofScienceandTechnologyofChina,Hefei230026）（KeyLaboratoryofElectromagneticSpaceInformation,ChineseAcademyofSciences,Hefei230026）AbstractZNSSSDisanewlyemergingsolidstatedrive(SSD).Itsupportszone-basedstorageandaccessofdatainSSD.ComparedwithtraditionalSSDs,ZNSSSDcaneffectivelyimprovetheread-writethroughputofSSD,reducewriteamplificationandover-provisioninginSSD.However,ZNSSSDrequiresthatdatamustbewrittentozonessequentially,andtaskssuchasspaceallocationandgarbagecollectionneedtobecontrolledbyusers.ThesecharacteristicsofZNSSSDposenewchallengestomanycomponentsintraditionaldatabasesystems,suchasstoragemanagement,indexing,andbuffermanagement.ThispapermainlystudieshowtoadaptthetraditionalB+-treeindexstructuretoZNSSSD.WeproposeanewZNSSSD-awareindexstructurecalledZB+-tree(ZNS-awareB+-tree),whichisthefirstZNSSSD-awareindexsofar.ZB+-treetakesB+-treeasthebasestructure,andutilizesthetwokindsofzonesinsideZNSSSD,namelyconventionalzonessupportingafewrandomwritesandsequentialzonesonlysupportingsequentialwrites.Inparticular,itusesconventionalzonestoabsorbrandomwritestoZNSSSDandstorestheindexnodesinconventionalandsequentialzonesseparately.Wedesigndifferentnodestructuresforthenodesinthetwozones.Byusingdifferenttypesofnodesonthetwozones,ZB+-treecanabsorbrandomwritesontheindexandensurethesequentialwriterequirementsonsequentialzones.WeconductexperimentsbysimulatingZNSSSDusingnull_blkandlibzbd.Also,wemodifytheexistingcopy-on-write(CoW)B+-treeasthecompetitor.TheresultsshowthatZB+-treeoutperformsCoWB+-treeinvariousmetricsincludingrunningtimeandspaceefficiency.KeywordsZNSSSD；B+-tree；databaseindex；CoWB+-tree；zonedstorage摘要ZNSSSD是近年来提出的一种新型固态硬盘（solidstatedrive，SSD），它以分区（Zone）的方式...
