CentOS6虛擬機擴展磁盤空間—lvm

CentOS6虛擬機擴展磁盤空間—lvm

本實驗基於CentOS 6.9，虛擬機有兩塊磁盤，/dev/sda做爲系統盤，/dev/sdb原來是一塊20G的磁盤，如今修改虛擬機的配置，擴展到40G。操做的是/dev/sdb

1、 咱們在pv和vg都是20G的時候，在vg_1上建立兩個lv
lvcreate -L 5G -n lv_b1 vg_1 #建立一個5G的lv，名字叫lv_b1

[root@CentOS69 ~]# lvcreate -L 14.79G -n lv_b2 vg_1 #建立一個14.97G的lv_b2
Rounding up size to full physical extent 14.79 GiB
Logical volume "lv_b2" created.
[root@CentOS69 ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
lv_b1 vg_1 -wi-a----- 5.00g
lv_b2 vg_1 -wi-a----- 14.79g

而後，建立兩個目錄，把這兩個lv掛載
[root@CentOS69 ~]# mkdir /mount1
[root@CentOS69 ~]# mkdir /mount2
[root@CentOS69 ~]# mkfs -t ext4 /dev/vg_1/lv_b1 #格式化
[root@CentOS69 ~]# mkfs -t ext4 /dev/vg_1/lv_b2 #格式化

[root@CentOS69 ~]# mount /dev/mapper/vg_1-lv_b1 /mount1 #掛載
[root@CentOS69 ~]# mount /dev/mapper/vg_1-lv_b2 /mount2 #掛載

[root@CentOS69 ~]# cp /etc/fstab /mount1 #複製一個文件到/mount1
[root@CentOS69 ~]# cp /etc/fstab /mount2 #複製一個文件到/mount2

2、 準備工做，安裝須要的軟件，先須要安裝epel的yum源，而後才能安裝後面的包，growpart這個軟件是咱們須要用到的，該軟件在epel源裏面

1. 安裝epel:
   yum install -y http://dl.Fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm

2. 安裝相關工具： yum install cloud-init cloud-utils-growpart dracut-modules-growroot -y

3. 從新生成initramfs
   dracut -f #覆蓋生成initramfs文件

3、 擴展之前的分區信息
注意：虛擬機在關機且沒有快照的狀況下才能進行擴展，對於阿里雲來說，磁盤擴容之後，須要在控制檯重啓服務器，才能看到增長的磁盤空間。

1. 查看磁盤原有的分區信息：
   [root@CentOS69 ~]# lsblk
   NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
   sdb 8:16 0 40G 0 disk #磁盤/dev/sdb顯示爲40GB
   ├─sdb1 8:17 0 203.9M 0 part
   └─sdb2 8:18 0 19.8G 0 part
   ├─vg_1-lv_b1 (dm-2) 253:2 0 5G 0 lvm /mount1
   └─vg_1-lv_b2 (dm-3) 253:3 0 14.8G 0 lvm /mount2

2.對磁盤分區進行擴容，將Free的空間都分配給/dev/sdb2
[root@CentOS69 ~]# growpart /dev/sdb 2
CHANGED: partition=2 start=417690 old: size=41511960 end=41929650 new: size=83457675,end=83875365

3.查看分區的空間信息，再次執行lsblk,
[root@CentOS69 ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sdb 8:16 0 40G 0 disk
├─sdb1 8:17 0 203.9M 0 part
└─sdb2 8:18 0 19.8G 0 part
├─vg_1-lv_b1 (dm-2) 253:2 0 5G 0 lvm /mount1
└─vg_1-lv_b2 (dm-3) 253:3 0 14.8G 0 lvm /mount2

4. 從內核讀取分區信息
   [root@CentOS69 ~]# partprobe
   Warning: WARNING: the kernel failed to re-read the partition table on /dev/sda (設備或資源忙). As a result, it may not reflect all of your changes until after reboot.
5. 此時須要重啓虛擬機，才能讀到新增的容量
   [root@CentOS69 ~]#reboot #重啓後，lsblk能看到/dev/sdb2的空間大小爲39.8G
   [root@CentOS69 ~]# mount /dev/mapper/vg_1-lv_b1 /mount1
   [root@CentOS69 ~]# mount /dev/mapper/vg_1-lv_b2 /mount2

可是sdb2是一個lvm，不能直接使用resize2fs擴容。

4、 對pv進行擴容，因爲咱們是在虛擬機上對/dev/sdb2磁盤分區進行了擴容，因此咱們使用pvresize對/dev/sdb2的PV進行擴容，擴容後，其大小顯示爲39.79g

1. 擴容以前的PV大小
   [root@CentOS69 ~]# pvs
   PV VG Fmt Attr PSize PFree
   /dev/sdb2 vg_1 lvm2 a--u 19.79g 19.79g

2. 進行擴容
   [root@CentOS69 ~]# pvresize /dev/sdb2
   Physical volume "/dev/sdb2" changed
   1 physical volume(s) resized / 0 physical volume(s) not resized
   [root@CentOS69 ~]# pvs
   PV VG Fmt Attr PSize PFree
   /dev/sdb2 vg_1 lvm2 a--u 39.79g 39.79g

若是上述的命令不能生效，那麼能夠手工指定pv的大小，在實驗中，我使用上述命令有時不生效，下面是直接設定pv的大小的

[root@CentOS69 ~]# pvresize --setphysicalvolumesize 39.8G /dev/sdb2
WARNING: /dev/sdb2: Overriding real size. You could lose data.
Physical volume "/dev/sdb2" changed
1 physical volume(s) resized / 0 physical volume(s) not resized
[root@CentOS69 ~]# pvs
Device /dev/sdb2 has size of 41511960 sectors which is smaller than corresponding PV size of 83464601 sectors. Was device resized?
One or more devices used as PVs in VG vg_1 have changed sizes.
PV VG Fmt Attr PSize PFree
/dev/sda2 vg_centos69 lvm2 a--u 29.51g 0
/dev/sdb2 vg_1 lvm2 a--u 39.80g 20.00g

5、 pv擴展完成之後，vg直接能夠識別出39.8G空間了。並顯示出有20G的空白空間

vgextend VGtest /dev/sdb #這是網上的擴容命令

[root@CentOS69 ~]# vgs
Device /dev/sdb2 has size of 41511960 sectors which is smaller than corresponding PV size of 83464601 sectors. Was device resized?
One or more devices used as PVs in VG vg_1 have changed sizes.
VG #PV #LV #SN Attr VSize VFree
vg_1 1 2 0 wz--n- 39.80g 20.00g

6、lv擴容
在擴容前，推薦使用lsblk來看一下，是否能看到擴容之後的分區

1. 擴容前的lv

[root@CentOS69 ~]# lvs
Device /dev/sdb2 has size of 41511960 sectors which is smaller than corresponding PV size of 83464601 sectors. Was device resized?
One or more devices used as PVs in VG vg_1 have changed sizes.
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
lv_b1 vg_1 -wi-a----- 5.00g
lv_b2 vg_1 -wi-a----- 14.79g

擴容的man文檔

1. Extends the size of the logical volume "vg01/lvol10" by 54MiB on physical volume /dev/sdk3.
   This is only possible if /dev/sdk3 is a member of volume group vg01 and there are enough
   free physical extents in it:

lvextend -L +54 /dev/vg01/lvol10 /dev/sdk3

2. Extends the size of logical volume "vg01/lvol01" by the amount of free space on physical
   volume /dev/sdk3. This is equivalent to specifying "-l +100%PVS" on the command line:

lvextend /dev/vg01/lvol01 /dev/sdk3

2. 擴容lv，加其增長20G空間
   [root@CentOS69 ~]# lvextend -L +20G /dev/vg_1/lv_b2
   Size of logical volume vg_1/lv_b2 changed from 14.79 GiB (3787 extents) to 34.79 GiB (8907 extents).
   Logical volume lv_b2 successfully resized.

3. 查看空間
   [root@CentOS69 ~]# lvs
   LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
   lv_b1 vg_1 -wi-ao---- 5.00g
   lv_b2 vg_1 -wi-ao---- 34.79g

網上另外一種對lv進行擴容的方法：
lvresize -l +100%FREE -r /dev/vg_1/lv_b2

7、對文件系統進行擴容

1. 查看已掛載的文件系統的空間
   [root@CentOS69 ~]# df -h
   Filesystem Size Used Avail Use% Mounted on
   /dev/mapper/vg_1-lv_b1 4.8G 10M 4.6G 1% /mount1
   /dev/mapper/vg_1-lv_b2 15G 37M 14G 1% /mount2

2.擴容
[root@CentOS69 ~]# resize2fs -p /dev/vg_1/lv_b2
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/vg_1/lv_b2 is mounted on /mount2; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 3
Performing an on-line resize of /dev/vg_1/lv_b2 to 9120768 (4k) blocks.
The filesystem on /dev/vg_1/lv_b2 is now 9120768 blocks long.

3.接下來，再使用df來查看的時候，擴容成功了
[root@CentOS69 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_1-lv_b1 4.8G 10M 4.6G 1% /mount1
/dev/mapper/vg_1-lv_b2 35G 37M 34G 1% /mount2

總結：擴容的思路是：先給虛擬機增長磁盤空間，對於操做系統來說，這是物理層面的空間增長； 接着，讓內核能識別出多的空間，並把它分配給分區；由於使用了lvm，接下來要從PV到VG到lv分別進行擴容；最後面是讓文件系統擴容。