LVM原理及詳細操作

LVMLVM是在磁盤分區(qū)和文件系統(tǒng)之間添加的一個邏輯層，來為文件系統(tǒng)屏蔽下層磁盤分區(qū)布局，提供一個抽象的盤卷，在盤卷上建立文件系統(tǒng)。首先我們討論以下幾個LVM術(shù)語：*物理存儲介質(zhì)（Thephysicalmedia）這里指系統(tǒng)的存儲設(shè)備：硬盤，是存儲系統(tǒng)最低層的存儲單元。*物理卷（physicalvolume）物理卷就是指硬盤分區(qū)或從邏輯上與磁盤分區(qū)具有同樣功能的設(shè)備（如RAID），是LVM的基本存儲邏輯塊，但和基本的物理存儲介質(zhì)（如分區(qū)、磁盤等）比較，卻包含有與LVM相關(guān)的管理參數(shù)。*卷組（VolumeGroup）LVM卷組類似于非LVM系統(tǒng)中的物理硬盤，其由物理卷組成?？梢栽诰斫M上創(chuàng)建一個或多個“LVM分區(qū)”（邏輯卷），LVM卷組由一個或多個物理卷組成。*邏輯卷（logicalvolume）LVM的邏輯卷類似于非LVM系統(tǒng)中的硬盤分區(qū)，在邏輯卷之上可以建立文件系統(tǒng)（比如/home或者/usr等）。*PE（physicalextent）每一個物理卷被劃分為稱為PE(PhysicalExtents）的基本單元，具有唯一編號的PE是可以被LVM尋址的最小單元。PE的大小是可配置的，默認為4MB。*LE（logicalextent）邏輯卷也被劃分為被稱為LE(LogicalExtents）的可被尋址的基本單位。在同一個卷組中，LE的大小和PE是相同的，并且一一對應(yīng)。首先可以看到，物理卷（PV）被由大小等同的基本單元PE組成。一個卷組由一個或多個物理卷組成。從上圖可以看到，PE和LE有著一一對應(yīng)的關(guān)系。邏輯卷建立在卷組上。邏輯卷就相當(dāng)于非LVM系統(tǒng)的磁盤分區(qū)，可以在其上創(chuàng)建文件系統(tǒng)。下圖是磁盤分區(qū)、卷組、邏輯卷和文件系統(tǒng)之間的邏輯關(guān)系的示意圖：和非LVM系統(tǒng)將包含分區(qū)信息的元數(shù)據(jù)保存在位于分區(qū)的起始位置的分區(qū)表中一樣，邏輯卷以及卷組相關(guān)的元數(shù)據(jù)也是保存在位于物理卷起始Command(mforhelp):wThepartitiontablehasbeenaltered!Callingioctl()tore-readpartitiontable.Syncingdisks.//查看分區(qū)后的物理磁盤(none):/home/liuzq/Desktop#fdisk-lDisk/dev/sda:107.3GB,107374182400bytes255heads,63sectors/track,13054cylindersUnits=cylindersof16065*512=8225280bytesDiskidentifier:0x000cd6a5DeviceBootStartEndBlocksIdSystem/dev/sda11143114861682Linuxswap/Solaris/dev/sda2*14413054103707607+83LinuxDisk/dev/sdb:107.3GB,107374182400bytes255heads,63sectors/track,13054cylindersUnits=cylindersof16065*512=8225280bytesDiskidentifier:0xe5260b42DeviceBootStartEndBlocksIdSystem/dev/sdb1113054104856223+83Linux//進入LVM模式(none):/home/liuzq/Desktop#lvm//查看LVM磁盤狀態(tài)----目前沒有任何LVM磁盤信息lvm>lvmdiskscan/dev/sda1[1.10GB]/dev/root[98.90GB]/dev/sdb1[100.00GB]1disk2partitions0LVMphysicalvolumewholedisks0LVMphysicalvolumes//查看LVM的配置文件lvm>dumpconfigdevices{ dir="/dev" scan="/dev" filter=["r|/dev/.*/by-path/.*|","r|/dev/.*/by-id/.*|","a/.*/"] cache="/etc/lvm/.cache" write_cache_state=1 sysfs_scan=1 md_component_detection=1}dmeventd{ mirror_library="libdevmapper-event-lvm2mirror.so.2.02" snapshot_library="libdevmapper-event-lvm2snapshot.so.2.02"}activation{ missing_stripe_filler="/dev/ioerror" mirror_region_size=512 reserved_stack=256 reserved_memory=8192 process_priority=-18}global{ umask=63 test=0 activation=1 proc="/proc" locking_type=1 locking_dir="/var/lock/lvm"}shell{ history_size=100}backup{ backup=1 backup_dir="/etc/lvm/backup" archive=1 archive_dir="/etc/lvm/archive" retain_min=10 retain_days=30}log{ verbose=0 syslog=1 overwrite=0 level=0 indent=1 command_names=0 prefix=""}//創(chuàng)建PVlvm>pvcreate/dev/sdb1Nophysicalvolumelabelreadfrom/dev/sdb1Physicalvolume"/dev/sdb1"successfullycreated//查看PV狀態(tài)lvm>pvdisplay"/dev/sdb1"isanewphysicalvolumeof"100.00GB"---NEWPhysicalvolume---PVName/dev/sdb1VGNamePVSize100.00GBAllocatableNOPESize(KByte)0TotalPE0FreePE0AllocatedPE0PVUUID7daSq9-7KXU-Lvil-SUHc-ELrI-fyX7-FM9Bfy//再次查看LVM磁盤狀態(tài)lvm>lvmdiskscan/dev/sda1[1.10GB]/dev/root[98.90GB]/dev/sdb1[100.00GB]LVMphysicalvolume1disk1partition0LVMphysicalvolumewholedisks1LVMphysicalvolume//創(chuàng)建VGlvm>vgcreatevg_test/dev/sdb1Volumegroup"vg_test"successfullycreated//查看VG狀態(tài)lvm>vgdisplay---Volumegroup---VGNamevg_testSystemIDFormatlvm2MetadataAreas1MetadataSequenceNo1VGAccessread/writeVGStatusresizableMAXLV0CurLV0OpenLV0MaxPV0CurPV1ActPV1VGSize100.00GBPESize4.00MBTotalPE25599AllocPE/Size0/0FreePE/Size25599/100.00GBVGUUIDoSUogC-mV2F-b7Dg-5sFa-tztZ-NDh4-fpL6zu//查看所有VGlvm>vgsVG#PV#LV#SNAttrVSizeVFreevg_test100wz--n-100.00G100.00G//創(chuàng)建LVlvm>lvcreate--size10G--namelvm_u1vg_testLogicalvolume"lvm_u1"created//查看LV狀態(tài)lvm>lvsLVVGAttrLSizeOriginSnap%MoveLogCopy%Convertlvm_u1vg_test-wi-a-10.00Glvm>vgsVG#PV#LV#SNAttrVSizeVFreevg_test110wz--n-100.00G90.00G//退出LVM配置模式lvm>exitExiting.//ext3格式化邏輯卷(none):/home/liuzq/Desktop#mkfs-text3-j/dev/vg_test/lvm_u1mke2fs1.41.1(01-Sep-2008)Filesystemlabel=OStype:LinuxBlocksize=4096(log=2)Fragmentsize=4096(log=2)655360inodes,2621440blocks131072blocks(5.00%)reservedforthesuperuserFirstdatablock=0Maximumfilesystemblocks=268435456080blockgroups32768blockspergroup,32768fragmentspergroup8192inodespergroupSuperblockbackupsstoredonblocks: 32768,98304,163840,229376,294912,819200,884736,1605632Writinginodetables:doneCreatingjournal(32768blocks):doneWritingsuperblocksandfilesystemaccountinginformation:doneThisfilesystemwillbeautomaticallycheckedevery26mountsor180days,whichevercomesfirst.Usetune2fs-cor-itooverride.//使用LVM//首先創(chuàng)建掛載點(none):/home/liuzq/Desktop#mkdir/mnt/u1//掛載卷(none):/home/liuzq/Desktop#mount/dev/vg_test/lvm_u1/mnt/u1///檢查磁盤空間(none):/home/liuzq/Desktop#df-m/mnt/u1/Filesystem1M-blocksUsedAvailableUse%Mountedon/dev/mapper/vg_test-lvm_u11008015194172%/mnt/u1(none):/home/liuzq/Desktop#ls/mnt/u1/lost+found(none):/home/liuzq/Desktop#ll/boot/total14056-rw-------1rootroot5122012-12-2009:15backup_mbrlrwxrwxrwx1rootroot12012-12-2009:00boot->.-rw-r--r--1rootroot12362009-02-2406:40boot.readme-rw-r--r--1rootroot901372009-02-2803:09config-9-5-defaultdrwxr-xr-x2rootroot5682012-12-2009:15grublrwxrwxrwx1rootroot262012-12-2009:21initrd->initrd-9-5-default-rw-r--r--1rootroot61993942012-12-2009:21initrd-9-5-default-rw-r--r--1rootroot4352002012-12-2009:15message-rw-r--r--1rootroot1412062009-02-2803:13symsets-9-5-default.tar.gz-rw-r--r--1rootroot4048042009-02-2803:12symtypes-9-5-default.gz-rw-r--r--1rootroot1195802009-02-2803:10symvers-9-5-default.gz-rw-r--r--1rootroo02-2803:01System.map-9-5-default-rw-r--r--1rootroot30043232009-02-2803:09vmlinux-9-5-default.gzlrwxrwxrwx1rootroot272012-12-2009:06vmlinuz->vmlinuz-9-5-default-rw-r--r--1rootroot25371842009-02-2803:01vmlinuz-9-5-default//在新建文件系統(tǒng)里復(fù)制一個大文件例如在/boot目錄里挑個內(nèi)核文件復(fù)制到/mnt/u1(none):/home/liuzq/Desktop#cp/boot/vmlinux-9-5-default.gz/mnt/u1///對復(fù)制過來的文件運行md5sum并保存校驗值留待后用(none):/home/liuzq/Desktop#md5sum/mnt/u1/vmlinux-9-5-default.gz71603654a26edc4faa85054cbe2900be/mnt/u1/vmlinux-9-5-default.gz(none):/home/liuzq/Desktop#ll/mnt/u1/total2956drwx------2rootroot163842013-01-0501:43lost+found-rw-r--r--1rootroot30043232013-01-0501:51vmlinux-9-5-default.gz//擴大LVM卷假定空間不夠用準備向LVM卷增加更多空間。首先卸載該卷并使用lvresize命令調(diào)整卷大小。然后還必須用e2fsck檢查整個文件系統(tǒng)并運行resize2fs調(diào)整該卷上ext3文件系統(tǒng)的大小//卸載(none):/home/liuzq/Desktop#umount/mnt/u1///調(diào)整卷大小(none):/home/liuzq/Desktop#lvresize--size20G/dev/vg_test/lvm_u1Extendinglogicalvolumelvm_u1to20.00GBLogicalvolumelvm_u1successfullyresized//檢查文件系統(tǒng)(none):/home/liuzq/Desktop#e2fsck-f/dev/vg_test/lvm_u1e2fsck1.41.1(01-Sep-2008)Pass1:Checkinginodes,blocks,andsizesPass2:CheckingdirectorystructurePass3:CheckingdirectoryconnectivityPass4:CheckingreferencecountsPass5:Checkinggroupsummaryinformation/dev/vg_test/lvm_u1:12/655360files(0.0%non-contiguous),80431/2621440blocks//調(diào)整文件系統(tǒng)大小(none):/home/liuzq/Desktop#resize2fs/dev/vg_test/lvm_u120Gresize2fs1.41.1(01-Sep-2008)Resizingthefilesystemon/dev/vg_test/lvm_u1to5242880(4k)blocks.Thefilesystemon/dev/vg_test/lvm_u1isnow5242880blockslong.在上面的例子中卷和文件系統(tǒng)的大小都調(diào)整為20G。下面重新掛載卷檢查磁盤空間和之前計算的md5sum//重新掛載(none):/home/liuzq/Desktop#mount/dev/vg_test/lvm_u1/mnt/u1(none):/home/liuzq/Desktop#df-m/mnt/u1/Filesystem1M-blocksUsedAvailableUse%Mountedon/dev/mapper/vg_test-lvm_u120159159189771%/mnt/u1(none):/home/liuzq/Desktop#ll/mnt/u1/total2956drwx------2rootroot163842013-01-0501:43lost+found-rw-r--r--1rootroot30043232013-01-0501:51vmlinux-9-5-default.gz(none):/home/liuzq/Desktop#md5sum/mnt/u1/vmlinux-9-5-default.gz71603654a26edc4faa85054cbe2900be/mnt/u1/vmlinux-9-5-default.gz(none):/home/liuzq/Desktop#lvmlvm>lvsLVVGAttrLSizeOriginSnap%MoveLogCopy%Convertlvm_u1vg_test-wi-ao20.00Glvm>vgsVG#PV#LV#SNAttrVSizeVFreevg_test110wz--n-100.00G80.00Glvm>lvdisplay---Logicalvolume---LVName/dev/vg_test/lvm_u1VGNamevg_testLVUUIDhO9SlO-6t9u-nHfE-tm0V-SQPC-827D-1EksZTLVWriteAccessread/writeLVStatusavailable#open1LVSize20.00GBCurrentLE5120Segments1AllocationinheritReadaheadsectorsauto-currentlysetto256Blockdevice253:0lvm>exitExiting.(none):/home/liuzq/Desktop#(none):/home/liuzq/Desktop#lvsLVVGAttrLSizeOriginSnap%MoveLogCopy%Convertlvm_u1vg_test-wi-ao20.00G縮小LVM卷縮減現(xiàn)有LVM卷里不需要的空間時也可以使用lvresize。和前面一樣在調(diào)整卷大小之前先卸載這個卷然后運行e2fsck檢查文件系統(tǒng)和resize2fs調(diào)整成較小尺寸(none):/home/liuzq/Desktop#umount/mnt/u1/(none):/home/liuzq/Desktop#e2fsck-f/dev/vg_test/lvm_u1e2fsck1.41.1(01-Sep-2008)Pass1:Checkinginodes,blocks,andsizesPass2:CheckingdirectorystructurePass3:CheckingdirectoryconnectivityPass4:CheckingreferencecountsPass5:Checkinggroupsummaryinformation/dev/vg_test/lvm_u1:12/1310720files(0.0%non-contiguous),122833/5242880blocks(none):/home/liuzq/Desktop#resize2fs/dev/vg_test/lvm_u115Gresize2fs1.41.1(01-Sep-2008)Resizingthefilesystemon/dev/vg_test/lvm_u1to3932160(4k)blocks.Thefilesystemon/dev/vg_test/lvm_u1isnow3932160blockslong.(none):/home/liuzq/Desktop#lvresize--size15G/dev/vg_test/lvm_u1WARNING:Reducingactivelogicalvolumeto15.00GBTHISMAYDESTROYYOURDATA(filesystemetc.)Doyoureallywanttoreducelvm_u1?[y/n]:yReducinglogicalvolumelvm_u1to15.00GBLogicalvolumelvm_u1successfullyresiz