本文系轉載,在此跟原作者表示感謝,轉載也就是做個備忘
原文地址:http://blog.csdn.net/evandeng2009/article/details/49814097
原文如下:
一、基礎概念
Cent0S 7默認啓用LVM2(Logical Volume Manager),把機器的一塊硬盤分爲兩個區sda1和sda2,其中分區sda1作爲系統盤/boot掛載,少量空間;sda2作爲一個物理卷並且完全作爲邏輯卷組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。而兩個分區sda1和sda2上都建立了文件系統XFS,文件系統XFS作爲RedHat的默認文件系統也有它的考慮,成爲繼ext3,ext4之後的主流文件系統。
幾個概念的關係:M個物理硬盤HD或者物理硬盤中的分區一起組建爲一個邏輯卷組VG及存儲池,在卷組VG中創建N個邏輯卷LV,在一個邏輯卷LV中創建文件系統比如xfs。物理硬盤/分區、邏輯卷有最小基本尋址單元,CentOS7默認的大小爲4MB,二者一一對應,類似於鏈接或者變量引用,但是一個二者關係並非一直不變,因爲物理硬盤可能發生變化而邏輯卷自動調整。創建卷組和邏輯卷,會類似於創建分區一樣在磁盤開始位置寫入卷的信息VGDA(卷組描述符區域,Volume Group Descriptor Area)用於識別。邏輯卷的好處在於屏蔽物理底層支撐,可自由擴展變更,而不用擔心硬盤或者分區的物理空間侷限,也就不會存在爲了擴展分區大小而去備份/擴展分區重新格式化硬盤等問題。
HD/分區--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磁盤生效
但是關鍵點在於,CentOS 7默認安裝時/home佔用太多空間,根目錄相較而言就小得多(只有50G),而OpenStack安裝以及存儲的東西都在根目錄下。上傳幾個鏡像說不定就把你的根目錄空間耗盡。不像其他文件系統ext3,ext4或者reiserfs等,有命令(resize2fs,resize_reiserfs)直接支持縮小文件系統的大小,默認安裝的xfs支持擴展增大但是不支持縮小空間!
二、步驟概覽
所以下面要做的步驟大概爲:(直接root用戶登錄系統,本機或者ssh root過去,如果使用當前普通用戶會遇到點不必要的麻煩)
1. 備份/home/用戶文件,要是沒啥內容則忽略這步(爲什麼非要這個/home,刪掉直接用root?還是保留它,它存在也有道理的,再說生產環境還是不要只用root)
2. umount /home 卸載並lvremove刪除這個home邏輯卷,釋放它的空間,vgdisplay查看卷組可用空間大小
3. lvcreate新建一個新的home卷,並在其上mkfs建立xfs文件系統,(分配掛載到/home - 不用更改/etc/fstab,重啓即可,) 拷貝回來之前的內容
(這個時候空餘的空間隨便你分配,可以再建立別的邏輯卷,或者直接空閒下來以後使用,也可以直奔主題的走下面的第四步)
4. 把之前的home邏輯卷釋放並分配新卷home之後剩下的空間,lvextend分配給root卷,並用命令xfs_growfs擴展它的文件系統空間
三、相關命令
看看大概的命令有哪些
# pv
- pvchange pvck pvcreate pvdisplay pvmove pvremove pvresize pvs pvscan
# vb
- vgcfgbackup vgchange vgconvert vgdisplay vgextend vgimportclone vgmknodes vgremove vgs
- vgsplit vgcfgrestore vgck vgcreate vgexport vgimport vgmerge vgreduce vgrename
- vgscan
- lvchange lvcreate lvextend lvmchange lvmdiskscan lvmetad lvmsar lvremove lvresize lvscan
- lvconvert lvdisplay lvm
四、默認安裝情況
# df -h //查看磁盤使用情況,邏輯卷的掛載格式爲/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
- /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
- --- 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 //查看邏輯卷情況,默認三個,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中的用戶數據[root@localhost /]# mkdir /backup && mv /home/* /backup
[root@localhost /]# ls /home/
2. 卸載這個/home並刪除邏輯卷home
# umount /home
# df -h //查看磁盤情況
- 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 //查看卷組可用空間
- --- 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
3. 新建一個卷home,fdisk格式化爲8e格式,文件系統還是搞爲xfs(同樣掛載到/home)
# lvcreate -L 50G -n home centos //L表示大小,默認單位爲M;n表示卷名;這裏的centos是CentOS7安裝系統的時候就默認建立好的卷組名
- 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 //查看邏輯卷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
- --- 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:激活卷組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
- 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
# df -h //現在來查看磁盤使用情況
- 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
4. 最後再把釋放出來多餘的空間分配給root卷並xfs_growfs擴展文件系統
# 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着;+號表示在原來的基礎上額外增加,不要加好則設定爲具體額度
- 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 //查看邏輯卷和卷組情況,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
# df -h //不使用xfs_growfs擴展文件系統,磁盤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
- 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
- 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