LVM簡介
Logical Volume Manager，縮寫為LVM，為邏輯捲軸管理員，主要分四層。
PV、VG、PE、LV。
本文在介紹如何使用VLM來管理PV、VG、PE、LV這幾個物件，讓你的兩顆硬碟變成一顆大硬碟。
下圖為LVM的結構，LV可以搭載著檔案系統，VG是將不同的硬碟變成一個群組（LV依附在VG身上），PV則是LVM的基本單位，可以是整顆硬碟，也可以是分割區（VG依附在PV身上）。
圖片取自維基百科
安裝LVM套件
| $apt-get install lvm2 dmsetup mdadm reiserfsprogs xfsprogs |
查看磁碟
由下列可知，共有兩顆硬碟，分別為sda、sdb。
其中sda已經被分割過了，分成sda1。
| $lsblk |
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 931.5G 0 disk
└─sda1 8:1 0 931.5G 0 part
sdb 8:16 0 931.5G 0 disk
|
管理硬碟
| $fdisk /dev/sda |
Welcome to fdisk (util-linux 2.29.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): m #指令查詢
Help:
Generic
d delete a partition
F list free unpartitioned space
l list known partition types
n add a new partition
p print the partition table
t change a partition type
v verify the partition table
i print information about a partition
Misc
m print this menu
x extra functionality (experts only)
Script
I load disk layout from sfdisk script file
O dump disk layout to sfdisk script file
Save & Exit
w write table to disk and exit
q quit without saving changes
Create a new label
g create a new empty GPT partition table
G create a new empty SGI (IRIX) partition table
o create a new empty DOS partition table
s create a new empty Sun partition table
Command (m for help): p #顯示磁碟分割區
Disk /dev/sda: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: C25BB6AD-BEB0-43F5-BDA2-34B067A5BEE5
Device Start End Sectors Size Type
/dev/sda1 2048 1953523711 1953521664 931.5G Microsoft basic data
Command (m for help): d #刪除sda1分割區
Selected partition 1
Partition 1 has been deleted.
Command (m for help): n #新增sda1分割區
Partition number (1-128, default 1): #Enter
First sector (34-1953525134, default 2048): #Enter
Last sector, +sectors or +size{K,M,G,T,P} (2048-1953525134, default 1953525134): [分割區大小]
#如:
#900G #輸入Enter直接將最大磁碟空間作為分割區
Created a new partition 1 of type 'Linux filesystem' and of size 931.5 GiB.
Partition #1 contains a ntfs signature.
Do you want to remove the signature? [Y]es/[N]o: Y
The signature will be removed by a write command.
Command (m for help): t #顯示分割區資訊
Selected partition 1
Hex code (type L to list all codes): L
1 EFI System C12A7328-F81F-11D2-BA4B-00A0C93EC93B
2 MBR partition scheme 024DEE41-33E7-11D3-9D69-0008C781F39F
3 Intel Fast Flash D3BFE2DE-3DAF-11DF-BA40-E3A556D89593
4 BIOS boot 21686148-6449-6E6F-744E-656564454649
5 Sony boot partition F4019732-066E-4E12-8273-346C5641494F
6 Lenovo boot partition BFBFAFE7-A34F-448A-9A5B-6213EB736C22
7 PowerPC PReP boot 9E1A2D38-C612-4316-AA26-8B49521E5A8B
8 ONIE boot 7412F7D5-A156-4B13-81DC-867174929325
9 ONIE config D4E6E2CD-4469-46F3-B5CB-1BFF57AFC149
10 Microsoft reserved E3C9E316-0B5C-4DB8-817D-F92DF00215AE
11 Microsoft basic data EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
12 Microsoft LDM metadata 5808C8AA-7E8F-42E0-85D2-E1E90434CFB3
13 Microsoft LDM data AF9B60A0-1431-4F62-BC68-3311714A69AD
14 Windows recovery environment DE94BBA4-06D1-4D40-A16A-BFD50179D6AC
15 IBM General Parallel Fs 37AFFC90-EF7D-4E96-91C3-2D7AE055B174
16 Microsoft Storage Spaces E75CAF8F-F680-4CEE-AFA3-B001E56EFC2D
17 HP-UX data 75894C1E-3AEB-11D3-B7C1-7B03A0000000
18 HP-UX service E2A1E728-32E3-11D6-A682-7B03A0000000
19 Linux swap 0657FD6D-A4AB-43C4-84E5-0933C84B4F4F
20 Linux filesystem 0FC63DAF-8483-4772-8E79-3D69D8477DE4
21 Linux server data 3B8F8425-20E0-4F3B-907F-1A25A76F98E8
22 Linux root (x86) 44479540-F297-41B2-9AF7-D131D5F0458A
23 Linux root (ARM) 69DAD710-2CE4-4E3C-B16C-21A1D49ABED3
24 Linux root (x86-64) 4F68BCE3-E8CD-4DB1-96E7-FBCAF984B709
25 Linux root (ARM-64) B921B045-1DF0-41C3-AF44-4C6F280D3FAE
26 Linux root (IA-64) 993D8D3D-F80E-4225-855A-9DAF8ED7EA97
27 Linux reserved 8DA63339-0007-60C0-C436-083AC8230908
28 Linux home 933AC7E1-2EB4-4F13-B844-0E14E2AEF915
29 Linux RAID A19D880F-05FC-4D3B-A006-743F0F84911E
30 Linux extended boot BC13C2FF-59E6-4262-A352-B275FD6F7172
31 Linux LVM E6D6D379-F507-44C2-A23C-238F2A3DF928
32 FreeBSD data 516E7CB4-6ECF-11D6-8FF8-00022D09712B
33 FreeBSD boot 83BD6B9D-7F41-11DC-BE0B-001560B84F0F
34 FreeBSD swap 516E7CB5-6ECF-11D6-8FF8-00022D09712B
Hex code (type L to list all codes): 31 #Linux LVM
Changed type of partition 'Linux filesystem' to 'Linux LVM'.
Command (m for help): w #寫入磁碟
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
|
查看分割區
| $fdisk -l |
Disk /dev/sda: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: C25BB6AD-BEB0-43F5-BDA2-34B067A5BEE5
Device Start End Sectors Size Type
/dev/sda1 2048 1953525134 1953523087 931.5G Linux LVM
Disk /dev/sdb: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 728CE52E-6C1B-4E7F-A83B-C18F1CD262BB
Device Start End Sectors Size Type
/dev/sdb1 2048 1953525134 1953523087 931.5G Linux LVM
|
建立LVM 物理卷
PV：物理卷，是LVM系統的最底層的，可以是整顆硬碟，也可以是分割區。
| $pvcreate /dev/sda1 /dev/sdb1 |
| Physical volume "/dev/sda1" successfully created. Physical volume "/dev/sdb1" successfully created. |
刪除LVM分割區為
pvremove /dev/sda1 /dev/sdb1
| $pvdisplay |
"/dev/sda1" is a new physical volume of "931.51 GiB"
--- NEW Physical volume ---
PV Name /dev/sda1
VG Name
PV Size 931.51 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID NtfgYB-D5IM-SRnU-gyXV-ZGCt-Pedw-6nZ0VT
"/dev/sdb1" is a new physical volume of "931.51 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb1
VG Name
PV Size 931.51 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID JebAUY-8Oes-Rh2g-g2vN-m3HP-MzgX-lE4oMn
|
建立LVM 卷組
範例將為此卷組命名為storage
| $ vgcreate storage /dev/sda1 /dev/sdb1 |
Volume group "storage" successfully created
|
查看卷組
| $vgdisplay |
--- Volume group ---
VG Name storage
System ID
Format lvm2
Metadata Areas 2
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 2
Act PV 2
VG Size 1.82 TiB
PE Size 4.00 MiB
Total PE 476932
Alloc PE / Size 0 / 0
Free PE / Size 476932 / 1.82 TiB
VG UUID 9nb5e5-cNqZ-OaDm-3b5H-G0WO-2Maq-KNcN8j
|
重新掃描LVM的VG並刷新快取
| $vgscan |
Reading volume groups from cache.
Found volume group "storage" using metadata type lvm2
|
建立LVM 邏輯卷
LV：邏輯卷，是從VG分出來的一段小空間，可建立檔案系統（EXT3、FAT、NTFS.....）
範例中直接將VG分給LV 1.8TB，使用的卷組為storage，邏輯卷命名為file。
| $lvcreate --name file --size 1.8T storage |
Rounding up size to full physical extent 1.80 TiB
Logical volume "file" created.
|
查看邏輯卷
| $lvdisplay |
--- Logical volume ---
LV Path /dev/storage/file
LV Name file
VG Name storage
LV UUID epxcZ2-7XL3-KjB3-9EP1-gQ7B-BWro-XZ33Vr
LV Write Access read/write
LV Creation host, time raspberrypi, 2018-09-19 23:54:37 +0800
LV Status available
# open 0
LV Size 1.80 TiB
Current LE 471860
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 254:0
|
重新掃描LVM的LV並刷新快取
| $lvscan |
ACTIVE '/dev/storage/file' [1.80 TiB] inherit
|
建立檔案系統
範例file的檔案系統使用FAT，可依使用改變。
| $mkfs.fat /dev/storage/file |
mkfs.fat 4.1 (2017-01-24)
|
查看磁碟
| $lsblk |
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 931.5G 0 disk
└─sda1 8:1 0 931.5G 0 part
└─storage-file 254:0 0 1.8T 0 lvm /media/storage
sdb 8:16 0 931.5G 0 disk
└─sdb1 8:17 0 931.5G 0 part
└─storage-file 254:0 0 1.8T 0 lvm /media/storage
mmcblk0 179:0 0 29.6G 0 disk
├─mmcblk0p1 179:1 0 1.4G 0 part
├─mmcblk0p2 179:2 0 1K 0 part
├─mmcblk0p5 179:5 0 32M 0 part /media/pi/SETTINGS
├─mmcblk0p6 179:6 0 69M 0 part /boot
└─mmcblk0p7 179:7 0 28.1G 0 part /
|
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