linux lvm管理详解.docx

LVM是什么，与普通的磁盘分区有什么区别，有什么优势如何创建LVM，如何增加其大小，如何减少其大小从PD到PV到VG再到LV，描述一下为什么它能实际在线扩容和缩减LVM是逻辑盘卷管理（LogicalVolumeManager）的简称，它是Linux环境下对磁盘分区进行管理的一种机制，LVM是建立在硬盘和 分区之上的一个逻辑层，来提高磁盘分区管理的灵活性。它最主要的功能是能灵活的调整分区的大小它是如何形成的呢？首先，可以将块设置成lvm格式，即在fdisk时设置为8e。那么这种块设置就从PD变成了PV。即物理卷。PV：物理卷 physical volumevg: 卷组：由多个PV可以组成一个卷组，每个PV只能属于一个卷组lv:逻辑卷，vg相当于一个逻辑磁盘，在这个逻辑的磁盘上，再来划分出逻辑的分区就是lv。可以对lv进行分区、格式化。pe: physical extend.相关于文件系统的block，一个vg的最大容量由PE的大小来决定。因为一个vg最多可以容纳65534个PE，PE的默认大小是4M。所以默认来说，如果不在创建卷组时更改PE的大小，这个vg的容量最多只有256G一、pv的命令pvcreate: initializeadiskorpartitionforusebyLVM格式： pvcreate 块设备名称.pvdisplay: displayattributesofaphysicalvolume格式 pvdisplay pv名称pvscanpvremove:removeaphysicalvolume格式 pvremove pv名称例： 在下面的sdb5-8，创建四个PVsector:扇区track：磁道cylinders：柱面Disk/dev/sdb:21.5GB,21474836480bytes255heads,63sectors/track,2610cylindersUnits=cylindersof16065*512=8225280bytesSectorsize(logical/physical):512bytes/512bytesI/Osize(minimum/optimal):512bytes/512bytesDiskidentifier:0x4ebf972fDeviceBootStartEndBlocksIdSystem/dev/sdb116545253223+83Linux/dev/sdb46552610157115705Extended/dev/sdb5655104731567418eLinuxLVM/dev/sdb61048144031567418eLinuxLVM/dev/sdb71441183331567418eLinuxLVM/dev/sdb81834222631567418eLinuxLVM/dev/sdb9222726103084448+83Linux创建PVrootcentos6#pvcreate/dev/sdb5,6,7,8Physicalvolume/dev/sdb5successfullycreatedPhysicalvolume/dev/sdb6successfullycreatedPhysicalvolume/dev/sdb7successfullycreatedPhysicalvolume/dev/sdb8successfullycreatedrootcentos6#pvsPV VG FmtAttrPSizePFree/dev/sda2vg_centos6lvm2a-59.51g0/dev/sdb5 lvm2a-3.01g3.01g/dev/sdb6 lvm2a-3.01g3.01g/dev/sdb7 lvm2a-3.01g3.01g/dev/sdb8 lvm2a-3.01g3.01gPV的名称 所属VG 磁盘格式 PV容量 PV空闲容量rootcentos6#pvdisplay-Physicalvolume-PVName/dev/sda2VGNamevg_centos6PVSize59.51GiB/notusable3.00MiBAllocatableyes(butfull)PESize4.00MiBTotalPE15234FreePE0AllocatedPE15234PVUUIDH6y2wC-Rc73-K3OU-Mn3R-ojvi-LhkB-1uaUpI/dev/sdb5isanewphysicalvolumeof3.01GiB-NEWPhysicalvolume-PVName/dev/sdb5VGNamePVSize3.01GiBAllocatableNOPESize0TotalPE0FreePE0AllocatedPE0PVUUIDAhsKzf-bnMj-Iefd-kI97-WtRX-S1IB-KEG24O/dev/sdb6isanewphysicalvolumeof3.01GiB-NEWPhysicalvolume-PVName/dev/sdb6VGNamePVSize3.01GiBAllocatableNOPESize0TotalPE0FreePE0AllocatedPE0PVUUIDnBeeU0-GggM-2UHO-zZ7M-g27G-UX2C-Q61zzu/dev/sdb7isanewphysicalvolumeof3.01GiB-NEWPhysicalvolume-PVName/dev/sdb7VGNamePVSize3.01GiBAllocatableNOPESize0TotalPE0FreePE0AllocatedPE0PVUUIDLRghKP-Ey0M-mSdx-BCZI-0rDV-OfyF-mGN9rg/dev/sdb8isanewphysicalvolumeof3.01GiB-NEWPhysicalvolume-PVName/dev/sdb8VGNamePVSize3.01GiBAllocatableNOPESize0TotalPE0FreePE0AllocatedPE0PVUUIDl2dy8X-2HSj-Nl8H-hsxD-3ApO-m9iA-NjlrT2二、创建VGvgcreate: vgcreate-createavolumegroup格式 vgcreate 选项 vg名 pv名称 -s : 指定pe的大小vgdisplay: 显示vg的状态vgscan： 查找系统上是否有vg存在vgextend： 在VG内增加额外的pvvgreduce: 将某个pv从vg中删除vgremove： 删除一个vg将上述4个3G的PV中的三个创建一个VG，PE大小为8Mrootcentos6#vgcreate-s8Mmyvg/dev/sdb5,6,7Volumegroupmyvgsuccessfullycreatedrootcentos6#vgsVG#PV#LV#SNAttrVSizeVFreemyvg300wz-n-9.02g9.02gvg_centos6130wz-n-59.51g0rootcentos6#vgdisplay-Volumegroup-VGNamemyvgSystemIDFormatlvm2MetadataAreas3MetadataSequenceNo1VGAccessread/writeVGStatusresizableMAXLV0CurLV0OpenLV0MaxPV0CurPV3ActPV3VGSize9.02GiBPESize8.00MiBTotalPE1155AllocPE/Size0/0FreePE/Size1155/9.02GiB VGUUID4r82zu-R0YK-fVVe-dTs6-bEtZ-i3rU-SI5xNT三、创建lvlvcreate -L #：后面接容量，可以是M、G等 -l #: 后面接PE的个数 -n : 后接由用户定义的lv名称格式： lvcreate 容量大小 名称 vg名称例：rootcentos6#lvcreate-L8G-nmylv/dev/myvg Logicalvolumemylvcreatedlvscanlvdisplaylvextendlvreducelvremovelvresizerootcentos6#lvscanACTIVE/dev/myvg/mylv8.00GiBinheritACTIVE/dev/vg_centos6/lv_root50.00GiBinheritACTIVE/dev/vg_centos6/lv_home5.57GiBinheritACTIVE/dev/vg_centos6/lv_swap3.94GiBinheritrootcentos6#lvdisplay/dev/myvg/mylv-Logicalvolume-LVPath/dev/myvg/mylvLVNamemylvVGNamemyvgLVUUID28bXXM-8I9A-ksWP-9DVg-4d66-sZIf-OvreFmLVWriteAccessread/writeLVCreationhost,timecentos6,2016-06-1717:01:55+0800LVStatusavailable#open0LVSize8.00GiBCurrentLE1024Segments3AllocationinheritReadaheadsectorsauto-currentlysetto256Blockdevice253:3四、格式化、挂载到/lvmrootcentos6/#mke2fs-j/dev/myvg/mylvrootcentos6/#mount/dev/myvg/mylv/lvmrootcentos6/#ls/lvmlost+foundrootcentos6/#df-hFilesystem SizeUsedAvailUse%Mountedon/dev/mapper/myvg-mylv7.9G147M7.4G2%/lvm五、高级特性之扩容由于业务需要，之前由三个块设备组成的VG，上面有一个lv叫mylv，容量已经不够用。现在需要扩容。经过pvs查看，发现还有一个pv可以加到这个vg中来rootcentos6/#pvsPVVGFmtAttrPSizePFree/dev/sda2vg_centos6lvm2a-59.51g0/dev/sdb5myvglvm2a-3.01g0/dev/sdb6myvglvm2a-3.01g0/dev/sdb7myvglvm2a-3.01g1.02g/dev/sdb8lvm2a-3.01g3.01g接下来，我们就来演示如何将pv /dev/sdb8加入到vg中，并且将扩大mylv这个lv的容量到可用的最大容量rootcentos6/#vgextendmyvg/dev/sdb8Volumegroupmyvgsuccessfullyextendedrootcentos6/#vgsVG#PV#LV#SNAttrVSizeVFreemyvg410wz-n-12.03g4.03gvg_centos6130wz-n-59.51g0从上面可以看到，我们的myvg还有4G的容量可供使用如果需要将一个lv扩容，需要遵循以下步骤1. 增加物理设备的容量2. 将物理设备转化成PV3. 将PV增加到VG extend4. 通过lvextend来增加lv的容量5. 通过resize2fs来增加lv里文件系统的容量前面3部已经完成了，接下来我们来将lv扩容lvextend或者lvresize,都可以实现扩容，我们以lvextend为例rootcentos6#vgdisplay-Volumegroup-VGNamemyvgSystemIDFormatlvm2MetadataAreas4MetadataSequenceNo3VGAccessread/writeVGStatusresizableMAXLV0CurLV1OpenLV1MaxPV0CurPV4ActPV4VGSize12.03GiBPESize8.00MiBTotalPE1540AllocPE/Size1024/8.00GiBFreePE/Size516/4.03GiB （有516个PE，共4.03G的空闲磁盘）VGUUID4r82zu-R0YK-fVVe-dTs6-bEtZ-i3rU-SI5xNTrootcentos6#lvextend-l+516/dev/myvg/mylvExtendinglogicalvolumemylvto12.03GiBLogicalvolumemylvsuccessfullyresizedrootcentos6#vgdisplay-Volumegroup-VGNamemyvgSystemIDFormatlvm2MetadataAreas4MetadataSequenceNo4VGAccessread/writeVGStatusresizableMAXLV0CurLV1OpenLV1MaxPV0CurPV4ActPV4VGSize12.03GiBPESize8.00MiBTotalPE1540AllocPE/Size1540/12.03GiBFreePE/Size0/0VGUUID4r82zu-R0YK-fVVe-dTs6-bEtZ-i3rU-SI5xNT现在lv的空间已经扩大到了12G，但文件系统的空间有多大呢？rootcentos6#df-lh/lvmFilesystemSizeUsedAvailUse%Mountedon/dev/mapper/myvg-mylv7.9G147M7.4G2%/lvm最后，我们需要使用resize2fs来扩展文件系统的空间，注意，文件系统的最大空间不能超过lv的大小，否则会出错的rootcentos6#resize2fs/dev/myvg/mylv 注意：这里被resize2fs的是lv设备，如果不指定大小的话，默认会使用所有的可用空间的resize2fs1.41.12(17-May-2010)Filesystemat/dev/myvg/mylvismountedon/lvm;on-lineresizingrequiredolddesc_blocks=1,new_desc_blocks=1Performinganon-lineresizeof/dev/myvg/mylvto3153920(4k)blocks.Thefilesystemon/dev/myvg/mylvisnow3153920blockslong.rootcentos6#df-lh/lvmFilesystemSizeUsedAvailUse%Mountedon/dev/mapper/myvg-mylv12G149M12G2%/lvm缩减lvm的容量大小如下所示：pv /dev/sdb5,6,7,8，构成了myvg，然后把所有的容量都给了lv: mylv。挂载到了/lvm上。现在我们准备要缩减lv的容量，把/dev/sdb5从这个lv中进行移除那么也就是说，需要将这个lv缩减3.01G的容量或者说是减少385个PE的大小rootcentos6#pvsPVVGFmtAttrPSizePFree/dev/sdb5myvglvm2a-3.01g0/dev/sdb6myvglvm2a-3.01g0/dev/sdb7myvglvm2a-3.01g0/dev/sdb8myvglvm2a-3.01g0rootcentos6/#pvdisplay/dev/sdb6-Physicalvolume-PVName/dev/sdb6VGNamemyvgPVSize3.01GiB/notusable2.75MiBAllocatableyes(butfull)PESize8.00MiBTotalPE385FreePE0AllocatedPE385PVUUIDnBeeU0-GggM-2UHO-zZ7M-g27G-UX2C-Q61zzurootcentos6#lvsLV VG Attr LSizePoolOriginData%MoveLogCpy%SyncConvertmylvmyvg-wi-ao-12.03g rootcentos6#df-lh/lvmFilesystem SizeUsed Avail Use%Mountedon/dev/mapper/myvg-mylv12G149M12G2% /lvmrootcentos6#mount/dev/mapper/myvg-mylvon/lvmtypeext3(rw) 解决方案：先确定文件系统的剩余空间，再确定/dev/sdb5的容量。 如上已经明确了需求，但要注意：不能在线缩减lv的容量，而且这个缩减是和增加是相反的。一、将文件系统umount umount /lvm二、进行文件系统的检查rootcentos6#e2fsck-f/dev/myvg/mylve2fsck1.41.12(17-May-2010)Pass1:Checkinginodes,blocks,andsizesPass2:CheckingdirectorystructurePass3:CheckingdirectoryconnectivityPass4:CheckingreferencecountsPass5:Checkinggroupsummaryinformation/dev/myvg/mylv:13/794624files(0.0%non-contiguous),612597/3153920blocks三、缩减文件系统的容量rootcentos6#resize2fs/dev/myvg/mylv8900Mresize2fs1.41.12(17-May-2010)Resizingthefilesystemon/dev/myvg/mylvto2278400(4k)blocks.Thefilesystemon/dev/myvg/mylvisnow2278400blockslong.四、挂载文件系统rootcentos6#mount/dev/myvg/mylv/lvmrootcentos6#df-lh/lvmFilesystemSizeUsedAvailUse%Mountedon/dev/mapper/myvg-mylv8.6G2.2G6.0G27%/lvm五、 缩减lv的容量rootcentos6#lvresize-l-385/dev/myvg/mylvWARNING:Reducingactiveandopenlogicalvolumeto9.02GiBTHISMAYDESTROYYOURDATA(filesystemetc.)Doyoureallywanttoreducemylv?y/n:yReducinglogicalvolumemylvto9.02GiB （需要确认已存的数据要小于9.02G才可以按y）Logicalvolumemylvsuccessfullyresizedrootcentos6#vgdisplay-Volumegroup-VGNamemyvgSystemIDFormatlvm2MetadataAreas4MetadataSequenceNo5VGAccessread/writeVGStatusresizableMAXLV0CurLV1OpenLV1MaxPV0CurPV4ActPV4VGSize12.03GiBPESize8.00MiBTotalPE1540AllocPE/Size1155/9.02GiBFreePE/Size385/3.01GiB（现在再来看，已经有385个PE是空闲的了）VGUUID4r82zu-R0YK-fVVe-dTs6-bEtZ-i3rU-SI5xNT六、使用命令来查看哪个PV上有空闲的PE，并把/dev/sdb6的数据移到那个有空闲PE的PV上rootcentos6#pvdisplay-Physicalvolume-PVName/dev/sdb5VGNamemyvgPVSize3.01GiB/notusable2.75MiBAllocatableyes(butfull)PESize8.00MiBTotalPE385FreePE0AllocatedPE385PVUUIDAhsKzf-bnMj-Iefd-kI97-WtRX-S1IB-KEG24O-Physicalvolume-PVName/dev/sdb6VGNamemyvgPVSize3.01GiB/notusable2.75MiBAllocatableyes(butfull)PESize8.00MiBTotalPE385FreePE0AllocatedPE385PVUUIDnBeeU0-GggM-2UHO-zZ7M-g27G-UX2C-Q61zzu-Physicalvolume-PVName/dev/sdb7VGNamemyvgPVSize3.01GiB/notusable2.75MiBAllocatableyes(butfull)PESize8.00MiBTotalPE385FreePE0AllocatedPE385PVUUIDLRghKP-Ey0M-mSdx-BCZI-0rDV-OfyF-mGN9rg-Physicalvolume-PVName/dev/sdb8VGNamemyvgPVSize3.01GiB/notusable2.75MiBAllocatab