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H3CCAS内存气球特性操作指导书Copyright2015杭州华三通信技术有限公司版权所有,保留一切权利.
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i目录1简介·······························································································································12产品规格·························································································································12.
1规格列表······················································································································12.
2注意事项······················································································································13配置前提·························································································································44配置环境·························································································································44.
1服务器·························································································································44.
2软件···························································································································45配置指导·························································································································55.
1组网拓扑······················································································································55.
2测试方法······················································································································65.
2.
1准备测试虚拟机····································································································65.
2.
2虚拟机加压··········································································································75.
2.
3虚拟化主机内存变化情况························································································75.
2.
4开启内存气球·······································································································911简介为了使虚拟机具有更好的伸缩性和可扩展性,在充分保证虚拟机访问内存性能的前提下,H3CCAS提供了内存过量分配(MemoryOvercommitment)等高级内存管理功能.
内存过量分配技术也称作内存动态分配技术,其目的是为了将物理服务器上的虚拟机密度最大化.
内存过量技术甚至允许虚拟机使用的虚拟内存总和超过物理内存大小.
业界一般通过三种机制来实现内存的过量分配.
(1)透明页共享(TransparentPageSharing,TPS)允许虚拟机之间只读地共享完全相同的内存区域,从而缓解大量虚拟机并发运行时的内存资源紧缺.
实现内存透明页共享的重要技术基础是写时复制(copyonwrite)机制.
基于内容的透明页共享技术将多个虚拟机上的相同内存仅保存一份,极大地节约了内存.
(2)内存气球驱动机制当同一个物理主机上的多个虚拟机之间出现内存竞争时,Hypervisor将轮询物理主机上所有的虚拟机,通过内存气球驱动自动回收虚拟机中的空闲内存.
内存气球驱动回收机制能够最大限度地提高内存资源的利用率.
(3)内存交换(Swapping)Hypervisor利用内存交换技术,给虚拟机分配超过实际物理机内存大小的内存空间.
通过将内存页面交换到硬盘,虚拟机上的操作系统能够像运行在裸机上一样,透明地使用虚拟化主机提供的整个"物理内存".
上述三种高级内存管理技术虽然缓解了内存过量分配时的资源紧缺问题,但是它们同时带来了虚拟机性能问题,例如,内存透明页的相同内存合并、内存气球的膨胀与压缩、内存磁盘交换等,都极大消耗Hypervisor主机的计算性能,直接影响运行于其上的虚拟机的业务性能.
本文档介绍H3CCAS内存气球特性的使用方法和操作步骤.
2产品规格2.
1规格列表一级规格二级规格说明虚拟化内核系统虚拟内存管理支持在线调整虚拟内存气球功能,即当同一个物理主机上的多个虚拟机出现内存资源竞争时,通过集成在CVK中的气球膨胀自动挤压出虚拟机的空闲内存.
支持内存交换技术,即在虚拟机内存紧缺时,将虚拟内存页面写入到磁盘中,缓解内存资源不足的问题.
2.
2注意事项(1)在实际生产业务环境中,不建议使用包括内存气球在内的所有高级内存管理功能,原因是:高级内存管理技术都是在资源出现严重紧缺的情况下才生效,而且,在生效期间,必然对虚拟机2的业务性能造成极大的影响,例如,在物理PC上常见的Windows操作系统虚拟内存不足即是这种情况.
在实际生产业务环境中,一定要从资源规划的角度出发,提前详细评估业务系统对资源的峰值消耗,提前为业务系统合理分配虚拟资源,而不是在出现资源不足的情况下,依靠软件来动态调整资源的分配,这种部署方式对业务本身的运行稳定性和性能都是不利的.
(2)在生产环境中,强烈不建议内存资源超配,原因有两点:内存资源超配可能导致服务器本身工作不稳定,过量超配使用时,极有可能出现各种不可预知的异常结果.
在虚拟化环境中,影响的对象包括该服务器上的所有虚拟机,轻者导致业务系统响应缓慢,影响用户体验,重者可能造成所有的业务系统异常.
根据标准数据中心建设和安全运维经验,CPU和内存等计算资源都不建议超过80%,如果超过该阈值,都要求给管理员告警.
也就是说,80%是计算资源的一个经验告警阈值,在正常业务运维过程中,CPU和内存利用率峰值都建议不超过该阈值.
(3)内存气球功能生效的必要前提是虚拟机正常安装了CAStools工具,且CAStools版本必须为2.
1.
2.
1及以上版本.
(4)如果为虚拟机配置了内存预留,则通过内存气球调整后的虚拟内存将不少于内存预留值.
(5)在对已经启用内存气球功能的虚拟机进行内存热添加时,可能会因为虚拟机内部显示内存与实际内存页面分配内存不一致而导致气球功能失效,因此,不建议对启用内存气球功能的虚拟机进行内存热添加操作.
(6)如果虚拟机操作系统为32位,则操作系统最大只支持4GB内存.
如果为虚拟机配置的内存容量超过其支持的最大内存容量,内存气球功能将失效.
各Windows操作系统支持的最大内存容量如下表所示.
操作系统支持的最大内存容量WindowsXPStarterEdition512MWindowsServer2003WebEditionWindows7StarterEdition2GBWindows2000ProfessionalEditionWindows2000ServerEditionWindowsXPHomeEditionWindowsXPProfessionalEditionWindowsXPEmbeddedEditionWindowsEmbeddedStandard2009WindowsEmbeddedStandard7WindowsVistaStarterEditionWindowsVistaHomeBasicWindowsVistaHomePremiumWindowsVistaBusinessEditionWindowsVistaEnterpriseEditionWindowsVistaUltimateEditionWindowsServer2003StandardEditionWindowsServer2003R2StandardEditionWindowsServer2003StandardEditionSP1WindowsSmallBusinessServer2003WindowsHomeServer4GB3WindowsStorageServer2003Windows7HomeBasicWindows7HomePremiumWindows7ProfessionalEditionWindows7EnterpriseEditionWindows7UltimateEditionWindows2000AdvancedServerEditionWindowsStorageServer2003EnterpriseEditionWindowsVistaHomeBasicx64Windows7HomeBasicx648GBWindowsVistaHomePremiumx64WindowsServer2003StandardEditionx64Windows7HomePremiumx6416GBWindows2000DatacenterServerEditionWindowsServer2003EnterpriseEditionWindowsServer2003R2StandardEditionx64WindowsServer2003StandardEditionSP1x64WindowsComputeClusterServer2003x64WindowsWebServer2008x64WindowsServer2008StandardEditionx6432GBWindowsServer2003EnterpriseEditionSP2WindowsServer2003EnterpriseEditionx64WindowsServer2008EnterpriseEditionWindowsServer2008DatacenterEdition64GBWindowsXPProfessionalEditionx64WindowsServer2003DatacenterEditionWindowsVistaBusinessEditionx64WindowsVistaEnterpriseEditionx64WindowsVistaUltimateEditionx64128GBWindowsEmbeddedStandard7x64Windows7ProfessionalEditionx64Windows7EnterpriseEditionx64Windows7UltimateEditionx64192GWindowsServer2003DatacenterEditionx64512GBWindowsServer2003R2EnterpriseEditionx64WindowsServer2003EnterpriseEditionSP1x64WindowsServer2003R2DatacenterEditionx64WindowsServer2003DatacenterEditionSP1x641TBWindowsServer2003EnterpriseEditionSP2x64WindowsServer2003DatacenterEditionSP2x64WindowsServer2008EnterpriseEditionx64WindowsServer2008DatacenterEditionx64WindowsServer2008IA642TB43配置前提本文档中的配置均是在实验室环境下进行的配置和验证,配置前服务器和软件的所有参数均采用出厂时的缺省配置.
如果您已经对被测试对象进行了配置,为了保证配置效果,请确认现有配置和以下举例中的配置不冲突.
4配置环境4.
1服务器本文档不严格与具体硬件服务器型号对应,如果使用过程中与产品实际情况有差异,请参考相关产品手册,或以设备实际情况为准.
本文档使用的服务器型号与配置如下表所示,该环境不作为实际部署时的强制环境或推荐环境,只需要服务器能够兼容H3CCAS云计算管理平台即可完成本配置.
配置项说明服务器#1(H3CCASCVM虚拟化管理平台)HPProLiantBL460cG7CPU:2路6核,IntelXeonX5675@3.
07GHz内存:96GB服务器#2(H3CCASCVK虚拟化内核系统)HPProLiantBL460cG7CPU:2路6核,IntelXeonX5675@3.
07GHz内存:96GB存储(共享存储设备)HPStoreVirtual45304.
2软件软件版本服务器虚拟化管理软件H3CCAS-E0222(KVMKernel3.
13.
6)虚拟机操作系统WindowsServer2008R2数据中心版SP164位RedHatEnterpriseLinuxServer6.
464位(内核版本:2.
6.
32-358)性能压力测试工具Windows软件名称:BurnInTestProfessionalEditionV7.
164位下载地址:http://www.
passmark.
com/download/bit_download.
htmLinux软件名称:Stress1.
0.
4下载地址:http://people.
seas.
harvard.
edu/~apw/stress/55配置指导5.
1组网拓扑图1内存气球测试组网逻辑拓扑图虚拟机操作系统vCPU个数虚拟内存大小IP地址VM#1WindowsServer2008R2数据中心版64位832GBDHCPVM#2WindowsServer2008R2数据中心版64位832GBDHCPVM#3RedHatEnterpriseLinuxServer6.
464位832GBDHCPVM#4RedHatEnterpriseLinuxServer6.
464位832GBDHCP(1)在服务器#2上创建四个虚拟机VM#1~VM#4,其中,VM#1和VM#2安装WindowsServer2008R2数据中心版64位操作系统,VM#3和VM#4安装RedHatEnterpriseLinuxServer6.
464位操作系统.
(2)为四个虚拟机分配的内存大小都为32GB,总计128GB内存,超过了服务器#2的物理内存96GB.
(3)首先不开启虚拟机的内存气球功能,在四个虚拟机VM#1~VM#4上同时运行加压工具软件,查看加压期间虚拟机的状态是否稳定,虚拟化主机内存利用率是否全部被占满(预期结果:虚拟机状态稳定,虚拟化主机内存利用率逐渐被占满).
(4)查看加压结束之后,观察虚拟化主机(服务器#2)物理内存是否被回收(预期结果:不会被回收).
6(5)为VM#1~VM#4开启内存气球功能,观察虚拟化主机(服务器#2)物理内存是否被回收(预期结果:被回收).
5.
2测试方法5.
2.
1准备测试虚拟机步骤1在服务器#2上创建虚拟机VM#1~VM#4,分别安装WindowsServer2008R2数据中心版64位(VM#1和VM#2)和RedHatEnterpriseLinuxServer6.
464位桌面版操作系统(VM#3和VM#4).
四个虚拟机硬件资源配置一致,如下表所示.
参数规格虚拟CPU个数2路4核虚拟内存大小32GB内存预留默认(0%,即不配置预留)虚拟磁盘大小20GB(共享存储)虚拟磁盘类型1*Virtio,智能格式虚拟磁盘格式智能格式(QCOW2)虚拟磁盘缓存模式默认(directsync)虚拟网卡类型1*Virtio虚拟交换机vSwitch0(复用管理网口)IP地址DHCP(默认)步骤2在H3CCASCVM虚拟化管理平台中,分别修改四个虚拟机,为虚拟机挂载CAStools工具,并在操作系统内安装CAStools.
步骤3为Windows虚拟机(VM#1和VM#2)安装PassMarkBurnInTestProfessionalEditionV7.
1加压工具软件.
步骤4为Linux虚拟机(VM#3和VM#4)安装Stress1.
0.
4加压工具软件.
[root@localhost~]#tarzxvfstress-1.
0.
4.
tar.
gz[root@localhost~]#cdstress-1.
0.
4[root@localhoststress-1.
0.
4]#.
/configure[root@localhoststress-1.
0.
4]#make[root@localhoststress-1.
0.
4]#makeinstall75.
2.
2虚拟机加压步骤1在VM#1和VM#2操作系统内运行PassMarkBurnInTestProfessionalEditionV7.
1加压工具软件,在主界面上菜单中,依次点击"Configuration"->"TestSelection&DutyCycles…",配置仅加压内存,加压比例为100%.
图2配置资源加压及比例步骤2在VM#3和VM#4操作系统命令行窗口中键入如下命令,表示使用32个内存进程,每个进程占用1GB字节,压力运行15分钟.
stress--vm32--vm-bytes1024M--timeout9005.
2.
3虚拟化主机内存变化情况步骤1在四个虚拟机上同时执行压力测试工具之前,观察虚拟化主机内存利用率保持在25%左右.
8图3加压之前虚拟化主机的内存利用率步骤2加压软件运行一段时间(约3~8分钟左右)之后,虚拟化主机的内存利用率逐渐攀升到100%左右.
图4加压期间虚拟化主机的内存利用率步骤315分钟加压结束之后,虚拟化主机的内存利用率一直没有下降,说明虚拟机并没有把加压期间申请的内存释放给虚拟化主机.
9图5未开启内存气球时虚拟化主机内存没有回收5.
2.
4开启内存气球步骤1在H3CCASCVM虚拟化管理平台中,分别修改四个虚拟机,为虚拟机开启内存气球功能.
图6为虚拟机开启内存气球功能10步骤2在H3CCASCVM虚拟化管理平台上,观察虚拟化主机内存利用率性能监控,发现为虚拟机开启内存气球之后,物理内存开始逐渐被回收.
图7开启内存气球后虚拟化主机内存逐渐回收