Linux 磁碟組劃分詳細介紹

基本概念：
磁碟、分割槽、物理卷【物理部分】
卷組【中間部分】
邏輯卷、檔案系統【虛擬化後可控制部分】

1. pv vg lv 物理卷組邏輯
pvdisplay
vgdisplay
lvdisplay
pvs
vgs
lvs

2.檢視檔案系統及其掛載點
# df -h
檔案系統容量已用可用已用%% 掛載點
/dev/sda3 26G 16G 8.7G 64% /
tmpfs 1.9G 0 1.9G 0% /dev/shm
/dev/sda1 504M 37M 443M 8% /boot
/dev/sdb1 109G 69G 35G 67% /var/lib/mysql

檔案系統可以是邏輯卷，也可以直接為物理分割槽。
/dev/mapper/VolGroup-lv_root 邏輯卷
/dev/sdb1 物理分割槽

3.磁碟資訊檢視
# fdisk -l
Disk /dev/sda: 32.2 GB, 32212254720 bytes
64 heads, 32 sectors/track, 30720 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0006dbeb

Device Boot Start End Blocks Id System
/dev/sda1 * 2 513 524288 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 514 4609 4194304 82 Linux swap / Solaris
Partition 2 does not end on cylinder boundary.
/dev/sda3 4610 30720 26737664 83 Linux
Partition 3 does not end on cylinder boundary.

Disk /dev/sdb: 118.1 GB, 118111600640 bytes
255 heads, 63 sectors/track, 14359 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x276e626e

Device Boot Start End Blocks Id System
/dev/sdb1 1 14359 115338636 83 Linux

兩個物理硬碟：
Disk /dev/sda:
Disk /dev/sdb:
除了顯示硬碟分割槽，同時顯示邏輯卷資訊，邏輯卷以vg_開頭

fdisk /dev/sdb 對物理磁碟進行分割槽。

案例操作：
擴容；/ 目錄增加8G

機器原本/目錄有22G，屬於邏輯卷。因此可以直接增加，如果是直接的物理磁碟，則不能在該目錄擴容
[root@mysqlsource]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-LogVol01
22G 16G 4.7G 77% /
tmpfs 3.8G 224K 3.8G 1% /dev/shm
/dev/sda1 485M 34M 427M 8% /boot

新增加硬碟（/dev/sdb 16G）：
[root@mysqlsource]# fdisk -l
Disk /dev/sda: 32.2 GB, 32212254720 bytes
64 heads, 32 sectors/track, 30720 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0008c51d
Device Boot Start End Blocks Id System
/dev/sda1 * 2 501 512000 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 502 30720 30944256 8e Linux LVM
Partition 2 does not end on cylinder boundary.
Disk /dev/mapper/VolGroup-LogVol01: 23.1 GB, 23089643520 bytes
255 heads, 63 sectors/track, 2807 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/VolGroup-LogVol00: 8594 MB, 8594128896 bytes
255 heads, 63 sectors/track, 1044 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/sdb: 17.2 GB, 17179869184 bytes
64 heads, 32 sectors/track, 16384 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

可以對/dev/sdb 進行分割槽
fdisk /dev/sdb
看到新建分割槽sdb1
fdisk -l

然後對sdb1建立成物理卷，也可以直接把/dev/sdb建立成物理卷

建立物理卷：
[root@mysqlsource ~]# pvcreate /dev/sdb
Physical volume "/dev/sdb" successfully created

檢視卷組 VolGroup
[root@mysqlsource ~]# vgs
VG #PV #LV #SN Attr VSize VFree
VolGroup 1 2 0 wz--n- 29.51g 0

新建的物理分割槽，分配到卷組VolGroup
[root@mysqlsource ~]# vgextend VolGroup /dev/sdb
Volume group "VolGroup" successfully extended

檢視需要新增的lv卷
[root@mysqlsource ~]# lvs
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
LogVol00 VolGroup -wi-ao--- 8.00g
LogVol01 VolGroup -wi-ao--- 21.50g

增加lv卷lvextend -L +[??]g /dev/[vg]/[lv] （加8G）
[root@mysqlsource ~]# lvextend -L +8G /dev/VolGroup/LogVol01
Extending logical volume LogVol01 to 29.50 GiB
Logical volume LogVol01 successfully resized

線上擴容 resize2fs /dev/[vg]/[lv]
[root@mysqlsource ~]# resize2fs /dev/VolGroup/LogVol01
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/VolGroup/LogVol01 is mounted on /; on-line resizing required
old desc_blocks = 2, new_desc_blocks = 2
Performing an on-line resize of /dev/VolGroup/LogVol01 to 7734272 (4k) blocks.
The filesystem on /dev/VolGroup/LogVol01 is now 7734272 blocks long.

空間已擴充套件為30G
[root@mysqlsource ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-LogVol01
30G 16G 13G 56% /
tmpfs 3.8G 224K 3.8G 1% /dev/shm
/dev/sda1 485M 34M 427M 8% /boot

vgs可以看到VolGroup擴充套件了容量，VFreee是剩下可用容量，如果顯示8.00G，
[root@mysqlsource ~]# vgs
VG #PV #LV #SN Attr VSize VFree
VolGroup 2 2 0 wz--n- 45.50g 8.00g
[root@mysqlsource ~]#

把剩餘8G加上
[root@mysqlsource ~]# lvextend -L +8G /dev/VolGroup/LogVol01
Extending logical volume LogVol01 to 37.50 GiB
Insufficient free space: 2048 extents needed, but only 2047 available
[root@mysqlsource ~]#
[root@mysqlsource ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-LogVol01
30G 16G 13G 56% /
tmpfs 3.8G 224K 3.8G 1% /dev/shm
/dev/sda1 485M 34M 427M 8% /boot
[root@mysqlsource ~]# resize2fs /dev/VolGroup/LogVol01
resize2fs 1.41.12 (17-May-2010)
The filesystem is already 7734272 blocks long. Nothing to do!

[root@mysqlsource ~]# lvextend -L +7G /dev/VolGroup/LogVol01
Extending logical volume LogVol01 to 36.50 GiB
Logical volume LogVol01 successfully resized
[root@mysqlsource ~]# resize2fs /dev/VolGroup/LogVol01
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/VolGroup/LogVol01 is mounted on /; on-line resizing required
old desc_blocks = 2, new_desc_blocks = 3
Performing an on-line resize of /dev/VolGroup/LogVol01 to 9569280 (4k) blocks.
The filesystem on /dev/VolGroup/LogVol01 is now 9569280 blocks long.

[root@mysqlsource ~]# vgs
VG #PV #LV #SN Attr VSize VFree
VolGroup 2 2 0 wz--n- 45.50g 1020.00m
[root@mysqlsource ~]#

新建邏輯卷並且掛載磁碟

fdisk /dev/sdc 進行分割槽，分成一個/dev/sdbc1物理磁碟

pvcreate:
[root@mysqlsource ~]# pvcreate /dev/sdc1
Physical volume "/dev/sdc1" successfully created

pvremove:
[root@mysqlsource ~]# pvremove /dev/sdc1
Labels on physical volume "/dev/sdc1" successfully wiped

vgcreate:
[root@mysqlsource ~]# vgcreate VolGroup1 /dev/sdc1
Volume group "VolGroup1" successfully created
[root@mysqlsource ~]# vgs
VG #PV #LV #SN Attr VSize VFree
VolGroup 2 2 0 wz--n- 45.50g 1020.00m
VolGroup1 1 0 0 wz--n- 1020.00m 1020.00m
[root@mysqlsource ~]#

vgremove:
[root@mysqlsource ~]# vgremove VolGroup1
Volume group "VolGroup1" successfully removed
[root@mysqlsource ~]#

lvcreate:
[root@mysqlsource ~]# lvcreate -n LogVol02 -L 1020m VolGroup1
Logical volume "LogVol02" created
[root@mysqlsource ~]# lvs
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
LogVol00 VolGroup -wi-ao--- 8.00g
LogVol01 VolGroup -wi-ao--- 36.50g
LogVol02 VolGroup1 -wi-a---- 1020.00m
[root@mysqlsource ~]#

lvremove:
[root@mysqlsource ~]# lvremove /dev/VolGroup1/LogVol02
Do you really want to remove active logical volume LogVol02? [y/n]: y
Logical volume "LogVol02" successfully removed
[root@mysqlsource ~]#

[root@mysqlsource ~]# lvs
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
LogVol00 VolGroup -wi-ao--- 8.00g
LogVol01 VolGroup -wi-ao--- 36.50g
LogVol02 VolGroup1 -wi-a---- 1020.00m

格式化檔案系統
[root@mysqlsource ~]# mkfs.ext4 /dev/VolGroup1/LogVol02
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
65280 inodes, 261120 blocks
13056 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=268435456
8 block groups
32768 blocks per group, 32768 fragments per group
8160 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376

Writing inode tables: done
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 20 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@mysqlsource ~]#
[root@mysqlsource ~]#
[root@mysqlsource ~]# mkdir /test

掛載檔案系統
[root@mysqlsource ~]# mount /dev/VolGroup1/LogVol02 /test

檢視
[root@mysqlsource ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-LogVol01
36G 16G 19G 46% /
tmpfs 3.8G 224K 3.8G 1% /dev/shm
/dev/sda1 485M 34M 427M 8% /boot
/dev/mapper/VolGroup1-LogVol02
1004M 18M 936M 2% /test
[root@mysqlsource ~]#

/home的掛載裝置對應的邏輯卷非常大，但是/掛載的邏輯卷空間較小，需要減小/home邏輯卷，加大/對應的邏輯卷。

umount /home【首先必須卸下掛載點，umount時相關裝置必須是空閒的，但是像/及/root有些系統服務無法被終止，也就無法umount，因此像/ /root這些掛載點最好安裝的時候最好就有所規劃，但是我們可以讓他擴大還是沒有問題】

在umount過程中如果有裝置佔用情況可使用

fuser -m -k /home終止相關程式，再次umount /home成功

df 看不到 /home掛載點

必須先檢測裝置對映

e2fsck -f /dev/mapper/vg_dbcentos6-lv_home

減小/home大小，原有4G，減小到1G

resize2fs /dev/mapper/vg_dbcentos6-lv_home 1G

重新掛載

mount /dev/mapper/vg_dbcentos6-lv_home /home

df -h 看到/home只剩1G了

以上只是減少了檔案裝置的大小，還要進一步減小對應邏輯卷大小

lvresize -L 1G /dev/mapper/vg_dbcentos6-lv_home【此過程會提示可能丟資料，如果有必要，請先備份

/home下資料在做操作】

lvresize -L +3GM /dev/mapper/vg_dbcentos6-lv_root【lv_root邏輯卷新增3G】

resize2fs /dev/mapper/vg_dbcentos6-lv_root 【這個命令不帶引數，表示把多出來的容量都加到當前檔案系統】

df -h【看到容量增加了】

總結一下案例2的過程，先umount、接下來efsck -f、接下來resize2fs要減小的檔案系統、mount檔案系統、

lvresize要減小的邏輯卷、lvresize要增大的邏輯卷、resize2fs要增大的檔案系統。

Linux 磁碟組劃分詳細介紹

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