一、基本概念
1、LVM是邏輯盤卷管理（LogicalVolumeManager）的簡稱，它是Linux環境下對磁盤分區進行管理的一種機制，LVM是建立在硬盤和分區之上的一個邏輯層，來提高磁盤分區管理的靈活性。
2、why：通常在安裝Linux系統的時候對磁盤進行一盤的分區，一旦日后分區或整個磁盤的空間不夠用，就難以再擴容。但是使用lvm來管理磁盤的分區，由于是建立在磁盤和分區上的一個邏輯層，可以靈活管理存儲空間，而且可以跨硬盤進行管理存儲空間，而且不會對原有的數據文件造成損害。
3、lvm的基本術語
PV：Physical Volume，指磁盤分區或從邏輯上與磁盤分區具有同樣功能的設備（如RAID），是LVM的基本存儲邏輯塊，但和基本的物理存儲介質（如分區、磁盤等）比較，卻包含有與LVM相關的管理參數。
PE：Physical Extent，每一個物理卷PV被劃分為稱為PE（Physical Extents）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。所以物理卷（PV）由大小等同的基本單元PE組成。
VG：Volume Group，類似于非LVM系統中的物理磁盤，其由一個或多個物理卷PV組成。可以在卷組上創建一個或多個LV（邏輯卷）。
LV：Logical Volume，類似于非LVM系統中的磁盤分區，邏輯卷建立在卷組VG之上。在邏輯卷LV之上可以建立文件系統（比如/home或者/usr等）。
LE：Logical Extent，邏輯卷LV也被劃分為可被尋址的基本單位，稱為LE。在同一個卷組中，LE的大小和PE是相同的，并且一一對應。
上述的基本關系如下圖
二、LVM的建立（配置LVM的流程：fdisk創建分區及修改ID為8e–>把分區轉換為PV—>創建VG—>創建LV—>格式華LV—>mount文件系統
1、常用工具
pv管理工具：
pvs：簡要pv信息顯示
pvdisplay：顯示pv的詳細信息
pvcreate /dev/DEVICE: 創建pv
-v:顯示過程
-f:強制，
-uuid:直接指定UUID
vg管理工具：
vgs
vgdisplay
vgcreate [-s #[kKmMgGtTpPeE]] VolumeGroupName PhysicalDevicePath [PhysicalDevicePath...][-s #[kKmMgGtTpPeE]]指定PE大小
vgextend VolumeGroupName PhysicalDevicePath [PhysicalDevicePath...]
vgreduce VolumeGroupName PhysicalDevicePath [PhysicalDevicePath...]
先做pvmove
vgremove
lv管理工具：
lvs
lvdisplay
lvcreate -L #[mMgGtT] -n NAME VolumeGroup
lvremove /dev/VG_NAME/LV_NAME
擴展邏輯卷：
lvextend -L [+]#[mMgGtT] /dev/VG_NAME/LV_NAME
resize2fs /dev/VG_NAME/LV_NAME
df -lh
縮減邏輯卷：
umount /dev/VG_NAME/LV_NAME
e2fsck -f /dev/VG_NAME/LV_NAME
resize2fs /dev/VG_NAME/LV_NAME #[mMgGtT]
lvreduce -L [-]#[mMgGtT] /dev/VG_NAME/LV_NAME
mount
快照：snapshot
lvcreate -L #[mMgGtT] -p r -s -n snapshot_lv_name original_lv_name
-p, --permission {r|rw}
-n, --name LogicalVolume{Name|Path}
-s, --snapshot OriginalLogicalVolume{Name|Path}
2、lvm的構建過程
先給系統添加硬盤并分區
[root@localhost ~]# fdisk /dev/sdc WARNING: DOS-compatible mode is deprecated. It's strongly recommended to switch off the mode (command 'c') and change display units to sectors (command 'u'). Command (mforhelp): tSelected partition1Hex code (typeLtolist codes): 8e //需要把分區的id修改為Linux LVMChangedsystemtypeofpartition1to8e (Linux LVM) Command (mforhelp): pDisk /dev/sdc: 10.7 GB, 10737418240bytes255 heads, 63 sectors/track, 1305 cylinders Units = cylinders of16065 * 512 = 8225280bytesSector size (logical/physical): 512bytes / 512bytesI/O size (minimum/optimal): 512bytes / 512bytesDisk identifier: 0x16f72b9f Device Boot StartEnd Blocks IdSystem/dev/sdc1 11305104823818e Linux LVM
1）、將磁盤設定為PV
[root@localhost ~]# pvcreate /dev/sda5 Physical volume "/dev/sda5" successfully created [root@localhost ~]# pvcreate /dev/sdb1 Physical volume "/dev/sdb1" successfully created [root@localhost ~]# pvcreate /dev/sdc1 Physical volume "/dev/sdc1" successfully created [root@localhost ~]# pvs PV VG Fmt Attr PSize PFree /dev/sda2 VolGroup lvm2 a-- 58.59g 0 /dev/sda5 lvm2 --- 10.00g 10.00g /dev/sdb1 lvm2 --- 10.00g 10.00g /dev/sdc1 lvm2 --- 10.00g 10.00g [root@localhost ~]# pvdisplay /dev/sdb1"/dev/sdb1" is a new physical volume of "10.00 GiB" --- NEW Physical volume --- PV Name /dev/sdb1 VG Name PV Size 10.00 GiB Allocatable NO PE Size 0 Total PE 0 Free PE 0 Allocated PE 0 PV UUID GGKTNl-Yi0I-5RJX-WiHJ-iQSe-tvzO-vqRo8N
2）、建立VG
[root@localhost ~]# vgcreate -s 6M myvg /dev/sda5 /dev/sd[b-c]1 //創建一個名為myvg的VG，并且設定PE大小為6M Volume group "myvg" successfully created [root@localhost ~]# vgs VG #PV #LV #SN Attr VSize VFree VolGroup 130 wz--n- 58.59g 0 myvg 300 wz--n- 29.98g 29.98g [root@localhost ~]# vgdisplay myvg --- Volume group --- VG Name myvg System ID Format lvm2 Metadata Areas 3 Metadata Sequence No 1 VG Access read/write VG Status resizable MAX LV 0 Cur LV 0 Open LV 0 Max PV 0 Cur PV 3 Act PV 3 VG Size 29.98 GiB PE Size 6.00 MiB Total PE 5117 Alloc PE / Size 0 / 0 Free PE / Size 5117 / 29.98 GiB VG UUID WtwVcH-Ny7F-kAcN-MI5H-0AgA-b6rF-fUiuJB [root@localhost ~]# pvdisplay /dev/sda5 --- Physical volume --- PV Name /dev/sda5 VG Name myvg //顯示此PE已經加入到myvg卷組中 PV Size 10.00 GiB / not usable 2.54 MiB Allocatable yes PE Size 6.00 MiB //PE大小由VG創建時確定，所以現在才有顯示大小 Total PE 1707 Free PE 1707 Allocated PE 0 PV UUID flJPpR-s9VI-OO5N-iSOm-K1nN-thOl-XknRjP
3）、建立LV
[root@localhost ~]# lvcreate -L 10G -n mylv myvg //創建一個名為mylv 10G大小的LV Rounding up size to full physical extent 10.00 GiB Logical volume "mylv" created. [root@localhost ~]# lvs //顯示LV的簡要信息 LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert LogVol00 VolGroup -wi-ao---- 39.06g LogVol01 VolGroup -wi-ao---- 9.76g LogVol02 VolGroup -wi-ao---- 9.77g mylv myvg -wi-a----- 10.00g [root@localhost ~]# lvdisplay /dev/myvg/mylv --- Logical volume --- LV Path /dev/myvg/mylv LV Name mylv VG Name myvg LV UUID RFCRTA-hd1C-6DPh-tVdK-EVy7-mF47-0qfTJh LV Write Access read/write //默認為讀寫模式 LV Creation host, time localhost.localdomain, 2016-06-1117:42:47 +0800 LV Status available # open 0 LV Size 10.00 GiB //10G大小 Current LE 1707 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:3
4）、格式化LV并掛載
[root@localhost ~]# mke2fs -t ext4 -L "myLVM" /dev/myvg/mylv mke2fs 1.41.12 (17-May-2010) 警告: 512 塊未使用. 文件系統標簽=myLVM 操作系統:Linux塊大小=4096 (log=2) 分塊大小=4096 (log=2)Stride=0 blocks, Stripe width=0 blocks656640 inodes, 2621440 blocks131097 blocks (5.00%) reserved for the super user 第一個數據塊=0Maximum filesystem blocks=268435456080block groups32768 blocks per group, 32768 fragments per group8208 inodes per groupSuperblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632正在寫入inode表: 完成 Creating journal (32768 blocks): 完成 Writing superblocks and filesystem accounting information: 完成 This filesystem will be automatically checked every 26 mounts or180 days, whichever comes first. Use tune2fs -c or -i to override. [root@localhost ~]# blkid /dev/myvg/mylv /dev/myvg/mylv: LABEL="myLVM"UUID="384e1993-9517-423a-b69b-26bbad53c3d3"TYPE="ext4" [root@localhost ~]# mount /dev/myvg/mylv /backup/ [root@localhost ~]# mount | grep "mylv"/dev/mapper/myvg-mylv on /backup type ext4 (rw)
3、lvm的擴展
[root@localhost ~]# lvextend -L +5G /dev/myvg/mylv //給mylv增加5G的空間大小 Rounding size to boundary between physical extents: 5.00 GiB Size of logical volume myvg/mylv changed from 10.00 GiB (1707 extents) to 15.01 GiB (2561 extents). Logical volume mylv successfully resized [root@localhost ~]# lvdisplay /dev/myvg/mylv --- Logical volume --- LV Path /dev/myvg/mylv LV Name mylv VG Name myvg LV UUID RFCRTA-hd1C-6DPh-tVdK-EVy7-mF47-0qfTJh LV Write Access read/write LV Creation host, time localhost.localdomain, 2016-06-1117:42:47 +0800 LV Status available # open 1 LV Size 15.01 GiB //已增加了5G的大小 Current LE 2561 Segments 2 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:2[root@localhost ~]# resize2fs /dev/myvg/mylv //最后還需要重新調整對應的文件系統的大小resize2fs 1.41.12 (17-May-2010) Filesystem at /dev/myvg/mylv is mounted on /backup; on-line resizing required old desc_blocks = 1, new_desc_blocks = 1Performing an on-line resize of /dev/myvg/mylv to 3933696 (4k) blocks. The filesystem on /dev/myvg/mylv is now 3933696 blocks long. [root@localhost ~]# df -lh /dev/myvg/mylv Filesystem Size Used Avail Use% Mounted on /dev/mapper/myvg-mylv 15G 25M 14G 1% /backup //此時顯示文件系統大小也也擴容后大小
4、LVM的縮減
[root@localhost ~]# umount /backup/ //①先卸載 [root@localhost ~]# e2fsck -f /dev/myvg/mylv //②強制檢測 e2fsck 1.41.12 (17-May-2010) 第一步: 檢查inode,塊,和大小 第二步: 檢查目錄結構 第3步: 檢查目錄連接性 Pass 4: Checking reference counts 第5步: 檢查簇概要信息 myLVM: 12/993168 files (0.0% non-contiguous), 101500/3933696 blocks [root@localhost ~]# resize2fs /dev/myvg/mylv 5G //③先縮減文件系統的大小到5Gresize2fs 1.41.12 (17-May-2010) Resizing the filesystem on /dev/myvg/mylv to1310720 (4k) blocks. The filesystem on /dev/myvg/mylv isnow1310720 blocks long. [root@localhost ~]# lvreduce -L5G /dev/myvg/mylv //④再縮減LV到5G大小 Rounding sizeto boundary betweenphysical extents: 5.00 GiB WARNING: Reducing active logical volume to5.00 GiB THIS MAY DESTROY YOUR DATA (filesystem etc.)Do you really want to reduce mylv? [y/n]: y Sizeoflogical volume myvg/mylv changedfrom15.01 GiB (2561 extents) to5.00 GiB (854 extents). Logical volume mylv successfully resized [root@localhost ~]# lvdisplay /dev/myvg/mylv --- Logical volume --- LV Path /dev/myvg/mylv LV Name mylv VG Name myvg LV UUID RFCRTA-hd1C-6DPh-tVdK-EVy7-mF47-0qfTJh LV Write Accessread/write LV Creation host, time localhost.localdomain, 2016-06-1117:42:47 +0800 LV Status available # open0 LV Size5.00 GiB //此時以顯示為縮減后的大小 Current LE 854 Segments 1 Allocation inherit Read ahead sectors auto - currently setto256Block device 253:2 [root@localhost ~]# mount /dev/myvg/mylv /backup/ //最后重新掛載 [root@localhost ~]# df -lh /dev/myvg/mylv Filesystem Size Used Avail Use% Mounted on/dev/mapper/myvg-mylv 4.8G20M4.6G1% /backup //文件系統此時也為5G大小
4、快照功能的實現
[root@localhost ~]# lvcreate -p r -s -L 512M -n snmylv /dev/myvg/mylv //創建一個大小為512M 只有讀權限的快照卷 Rounding up size to full physical extent 516.00 MiB Logical volume "snmylv" created. [root@localhost ~]# ll /dev/myvg總用量 0lrwxrwxrwx. 1 root root 7 6月 11 18:51 mylv -> ../dm-2lrwxrwxrwx. 1 root root 7 6月 11 18:51 snaplv -> ../dm-6lrwxrwxrwx. 1 root root 7 6月 11 18:51 snmylv -> ../dm-8[root@localhost ~]# lvdisplay /dev/myvg/snmylv --- Logical volume --- LV Path /dev/myvg/snmylv LV Name snmylv VG Name myvg LV UUID QG7ORH-YRyE-RTFA-JRCe-WhGk-mXAL-rjo0sl LV Write Access read only //只讀權限 LV Creation host, time localhost.localdomain, 2016-06-11 18:51:15 +0800 LV snapshot status active destination for mylv LV Status available # open 0 LV Size 5.00 GiB //原卷大小 Current LE 854 COW-table size 516.00 MiB //快照卷大小 COW-table LE 86 Allocated to snapshot 0.00% Snapshot chunk size 4.00 KiB Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:8
原創文章，作者：mouse015110，如若轉載，請注明出處：http://www.www58058.com/18082
