LVM----從CentOS7預設安裝的/home中轉移空間到根目錄/
阿新 • • 發佈:2021-10-30
LVM----從CentOS7預設安裝的/home中轉移空間到根目錄/
一、基礎概念
Cent0S 7預設啟用LVM2(Logical Volume Manager),把機器的一塊硬碟分為兩個區sda1和sda2,其中分割槽sda1作為系統盤/boot掛載,少量空間;sda2作為一個物理卷並且完全作為邏輯卷組VG(Volume Group)centos,在這個邏輯卷組centos中建立三個邏輯卷LV(Logical Volume)root和home還有swap,分別掛載到根目錄/和/home以及swap。而兩個分割槽sda1和sda2上都建立了檔案系統XFS,檔案系統XFS作為RedHat的預設檔案系統也有它的考慮,成為繼ext3,ext4之後的主流檔案系統。 幾個概念的關係:M個物理硬碟HD或者物理硬碟中的分割槽一起組建為一個邏輯卷組VG及儲存池,在卷組VG中建立N個邏輯卷LV,在一個邏輯卷LV中建立檔案系統比如xfs。物理硬碟/分割槽、邏輯卷有最小基本定址單元,CentOS7預設的大小為4MB,二者一一對應,類似於連結或者變數引用,但是一個二者關係並非一直不變,因為物理硬碟可能發生變化而邏輯卷自動調整。建立卷組和邏輯卷,會類似於建立分割槽一樣在磁碟開始位置寫入卷的資訊VGDA(卷組描述符區域,Volume Group Descriptor Area)用於識別。邏輯卷的好處在於遮蔽物理底層支撐,可自由擴充套件變更,而不用擔心硬碟或者分割槽的物理空間侷限,也就不會存在為了擴充套件分割槽大小而去備份/擴充套件分割槽重新格式化硬碟等問題。 HD/分割槽--通過pvcreate->PV--通過vgcreate(vgchange)/vgextend-->VG--通過lvcreate/lvextend-->LV--通過mkfs-->FS--通過xfs_growfs等-->df磁碟生效 但是關鍵點在於,CentOS 7預設安裝時/home佔用太多空間,根目錄相較而言就小得多(只有50G),而OpenStack安裝以及儲存的東西都在根目錄下。上傳幾個映象說不定就把你的根目錄空間耗盡。不像其他檔案系統ext3,ext4或者reiserfs等,有命令(resize2fs,resize_reiserfs)直接支援縮小檔案系統的大小,預設安裝的xfs支援擴充套件增大但是不支援縮小空間!二、步驟概覽
三、相關命令
[root@sunli ~]# pv pvchange pvck pvcreate pvdisplay pvmove pvremove pvresize pvs pvscan [root@sunli ~]# vg vgcfgbackup vgck vgdisplay vgimport vgmknodes vgrename vgsplit vgcfgrestore vgconvert vgexport vgimportclone vgreduce vgs vgchange vgcreate vgextend vgmerge vgremove vgscan [root@sunli~]# lv lvchange lvdisplay lvmconf lvmdump lvmsadc lvremove lvs lvconvert lvextend lvmconfig lvmetad lvmsar lvrename lvscan lvcreate lvm lvmdiskscan lvmpolld lvreduce lvresize
四、預設安裝情況
# df -h //檢視磁碟使用情況,邏輯卷的掛載格式為/dev/mapper/VolumeGroupName-LogicalVolumeName Filesystem Size Used Avail Use% Mounted on /dev/mapper/centos-root 50G 4.8G 46G 10% / devtmpfs 3.9G 0 3.9G 0% /dev tmpfs 3.9G 140K 3.9G 1% /dev/shm tmpfs 3.9G 8.9M 3.9G 1% /run tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup /dev/mapper/centos-home 873G 12G 862G 2% /home /dev/sda1 494M 133M 362M 27% /boot
# cat /etc/fstab /dev/mapper/centos-root / xfs defaults 0 0 UUID=6abe266a-12fe-4361-9417-8d317bc25c8d /boot xfs defaults 0 0 /dev/mapper/centos-home /home xfs defaults 0 0 /dev/mapper/centos-swap swap swap defaults 0 0
# vgdisplay //檢視邏輯卷組情況 --- Volume group --- VG Name centos System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 6 VG Access read/write VG Status resizable MAX LV 0 Cur LV 3 Open LV 3 Max PV 0 Cur PV 1 Act PV 1 VG Size 931.02 GiB PE Size 4.00 MiB Total PE 238341 Alloc PE / Size 238325 / 930.96 GiB Free PE / Size 16 / 64.00 MiB VG UUID IFQnYm-fCLh-38mD-Duid-nYXQ-qktX-3F1atk
# lvdisplay //檢視邏輯卷情況,預設三個,root、home和交換空間swap --- Logical volume --- LV Path /dev/centos/swap LV Name swap VG Name centos LV UUID FGrPuO-2T02-1OfG-0dcz-oVTy-qcsh-IxEmd4 LV Write Access read/write LV Creation host, time localhost, 2015-11-11 04:46:00 +0800 LV Status available # open 2 LV Size 7.75 GiB Current LE 1984 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:1 --- Logical volume --- LV Path /dev/centos/home LV Name home VG Name centos LV UUID x7Oh0t-6R1x-ey7G-G5OX-PnBO-VI0C-kcRuvO LV Write Access read/write LV Creation host, time localhost, 2015-11-11 04:46:01 +0800 LV Status available # open 1 LV Size 873.21 GiB Current LE 223541 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:2 --- Logical volume --- LV Path /dev/centos/root LV Name root VG Name centos LV UUID PgscNL-rvyY-21Z1-tVe3-80vC-ONCw-VlvmYs LV Write Access read/write LV Creation host, time localhost, 2015-11-11 04:46:04 +0800 LV Status available # open 1 LV Size 50.00 GiB Current LE 12800 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:0
五、操作步驟
1. 備份/home中的使用者資料
[root@localhost /]# mkdir /backup && mv /home/* /backup [root@localhost /]# ls /home/
2. 解除安裝這個/home並刪除邏輯卷home
# umount /home # df -h //檢視磁碟情況 Filesystem Size Used Avail Use% Mounted on /dev/mapper/centos-root 50G 17G 34G 33% / devtmpfs 3.9G 0 3.9G 0% /dev tmpfs 3.9G 84K 3.9G 1% /dev/shm tmpfs 3.9G 9.0M 3.9G 1% /run tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup /dev/sda1 494M 133M 362M 27% /boot
# lvremove /dev/centos/home //刪除邏輯卷home Do you really want to remove active logical volume home? [y/n]: y Logical volume "home" successfully removed
# vgdisplay //檢視卷組可用空間 --- Volume group --- VG Name centos System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 7 VG Access read/write VG Status resizable MAX LV 0 Cur LV 2 Open LV 2 Max PV 0 Cur PV 1 Act PV 1 VG Size 931.02 GiB PE Size 4.00 MiB Total PE 238341 Alloc PE / Size 14784 / 57.75 GiB Free PE / Size 223557 / 873.27 GiB VG UUID IFQnYm-fCLh-38mD-Duid-nYXQ-qktX-3F1atk這裡注意,Free PE / Size 中顯示的空間為卷組的空閒空間873G,之前為64M,也就是剛才刪除的邏輯卷home所佔用的空間,我們就從這個當中拿出一部分比如50G作為home
3. 新建一個卷home,fdisk格式化為8e格式,檔案系統還是搞為xfs(同樣掛載到/home)
# lvcreate -L 50G -n home centos //L表示大小,預設單位為M;n表示卷名;這裡的centos是CentOS7安裝系統的時候就預設建立好的卷組名 WARNING: xfs signature detected on /dev/centos/home at offset 0. Wipe it? [y/n]: y Wiping xfs signature on /dev/centos/home. Logical volume "home" created.
# lvdisplay //檢視邏輯卷home --- Logical volume --- LV Path /dev/centos/home LV Name home VG Name centos LV UUID b5lLlv-FQPY-dT43-SmzV-sSLA-4QqP-gdQqAP LV Write Access read/write LV Creation host, time localhost, 2015-11-13 14:05:06 +0800 LV Status available # open 0 LV Size 50.00 GiB Current LE 12800 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:2
# vgdisplay //再次檢視卷組空間大小 --- Volume group --- VG Name centos System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 8 VG Access read/write VG Status resizable MAX LV 0 Cur LV 3 Open LV 2 Max PV 0 Cur PV 1 Act PV 1 VG Size 931.02 GiB PE Size 4.00 MiB Total PE 238341 Alloc PE / Size 27584 / 107.75 GiB Free PE / Size 210757 / 823.27 GiB VG UUID IFQnYm-fCLh-38mD-Duid-nYXQ-qktX-3F1atk
# vgchange -ay centos //可選步驟:啟用卷組centos,使得這個新建的home邏輯卷生效(用vgchange而不用lvchange) 3 logical volume(s) in volume group "centos" now active
# mkfs -t xfs /dev/centos/home //在新建的邏輯卷home上建立xfs檔案系統 meta-data=/dev/centos/home isize=256 agcount=4, agsize=3276800 blks = sectsz=4096 attr=2, projid32bit=1 = crc=0 finobt=0 data = bsize=4096 blocks=13107200, imaxpct=25 = sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0 ftype=0 log =internal log bsize=4096 blocks=6400, version=2 = sectsz=4096 sunit=1 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0
# mount /dev/centos/home /home/ //把這個新邏輯卷home掛到之前的資料夾/home中去,直接重啟用fstab來掛載也行
# df -h //現在來檢視磁碟使用情況 Filesystem Size Used Avail Use% Mounted on /dev/mapper/centos-root 50G 17G 34G 33% / devtmpfs 3.9G 0 3.9G 0% /dev tmpfs 3.9G 84K 3.9G 1% /dev/shm tmpfs 3.9G 9.0M 3.9G 1% /run tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup /dev/sda1 494M 133M 362M 27% /boot /dev/mapper/centos-home 50G 33M 50G 1% /home
# mv /backup/* /home/ //再把之前拷出來的東西拷回新建的/home中,拷貝完成就可以直接用這個普通使用者來桌面登入系統了,不用重啟
4. 最後再把釋放出來多餘的空間分配給root卷並xfs_growfs擴充套件檔案系統
# lvextend -L +823G /dev/centos/root //把剩下的823G現在分配給root卷,剩下那點渣渣空間讓它閒著;+號表示在原來的基礎上額外增加,不要加好則設定為具體額度 Size of logical volume centos/root changed from 50.00 GiB (12800 extents) to 873.00 GiB (223488 extents). Logical volume root successfully resized
# lvdisplay //檢視邏輯卷和卷組情況,這下root的空間就多達到873G,之前的是50G --- Logical volume --- LV Path /dev/centos/root LV Name root VG Name centos LV UUID PgscNL-rvyY-21Z1-tVe3-80vC-ONCw-VlvmYs LV Write Access read/write LV Creation host, time localhost, 2015-11-11 04:46:04 +0800 LV Status available # open 1 LV Size 873.00 GiB Current LE 223488 Segments 2 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:0
# vgchange -ay centos //可選步驟:再次啟用下卷組centos
# df -h //不使用xfs_growfs擴充套件檔案系統,磁碟是不認得多的空間的 Filesystem Size Used Avail Use% Mounted on /dev/mapper/centos-root 50G 4.8G 46G 10% / devtmpfs 3.9G 0 3.9G 0% /dev tmpfs 3.9G 140K 3.9G 1% /dev/shm tmpfs 3.9G 9.0M 3.9G 1% /run tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup /dev/sda1 494M 133M 362M 27% /boot /dev/mapper/centos-home 50G 12G 39G 23% /home
# xfs_growfs /dev/centos/root //擴充套件root卷 meta-data=/dev/mapper/centos-root isize=256 agcount=4, agsize=3276800 blks = sectsz=4096 attr=2, projid32bit=1 = crc=0 finobt=0 data = bsize=4096 blocks=13107200, imaxpct=25 = sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0 ftype=0 log =internal bsize=4096 blocks=6400, version=2 = sectsz=4096 sunit=1 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0 data blocks changed from 13107200 to 228851712
# df -h //再看root大小已經生效,800多G了 Filesystem Size Used Avail Use% Mounted on /dev/mapper/centos-root 873G 4.8G 869G 1% / devtmpfs 3.9G 0 3.9G 0% /dev tmpfs 3.9G 140K 3.9G 1% /dev/shm tmpfs 3.9G 9.0M 3.9G 1% /run tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup /dev/sda1 494M 133M 362M 27% /boot /dev/mapper/centos-home 50G 12G 39G 23% /home
六、命令彙總
簡單總結下,就是下面幾條命令:# mkdir /backup # mv /home/* /backup/ # umount /home # lvremove /dev/centos/home # lvcreate -L 50G -n home cents # mkfs -t xfs /dev/centos/home # mv /backup/* /home/ # lvextend -L +xxxG /dev/centos/root # xfs_growfs root # rm -rf /backup
新盤做LVM,思路---PV----VG---LV
lsblk ##建立PV pvcreate /dev/sdb ##檢視當前PV pvscan 或者 pvs ##建立VG vgcreate datevg /dev/sdb (datavg是起的VG名字) ##檢視當前VG vgscan ##加入新的PV到VG datevg vgextend datevg /dev/sdc #建立LV lvcreate -L 200M -n lv1 datavg (-L(指定lv的大小) 指定為200m lv1為起的LV名字 從datevg裡建立) ## 檢視LV lvscan /dev/datevg/lv1 200m ##格式化,建立檔案系統掛載 mkfs.xfs /dev/datevg/lv1 或者 mkfs.ext4 /dev/datevg/lv1 mkdir /mnt/lv1 ##臨時掛載 mount /dev/datevg/lv1 /mnt/lv1 mount -a df -h (df-Th) 加上TYPE 型別 LVM完成
LVM的解除安裝 [root@localhost ~]# lvremove /dev/datavg/lv1 [root@localhost ~]# vgremove datavg [root@localhost ~]# pvremove /dev/sdb