Logical Volume Managerを利用してみる。
物理ボリュームを論理ボリュームとして扱えるようにして柔軟なディスク管理を実行できるようにする。
PV(Physical Volume)から
VG(Volume Group)を作り
LV(Logical Volume)として柔軟に扱えるようにする。
手ごろなサンプルをawsのec2を用いて試します。
amazon-linuxを準備
- 一番小さなインスタンスでよし
初期状態
# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda 202:0 0 8G 0 disk
└─xvda1 202:1 0 8G 0 part /
# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 236M 56K 236M 1% /dev
tmpfs 246M 0 246M 0% /dev/shm
/dev/xvda1 7.8G 981M 6.7G 13% /
EBSをアタッチする
awsコンソールから15Gぶんをアタッチする。awsコンソール上では/dev/sdfとして見えるが、SSHでコマンドを発行して確認するとxvdfとして認識されている。
# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda 202:0 0 8G 0 disk
└─xvda1 202:1 0 8G 0 part /
xvdf 202:80 0 15G 0 disk
# fdisk -l
Disk /dev/xvda: 8589 MB, 8589934592 bytes, 16777216 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
Disk label type: gpt
# Start End Size Type Name
1 4096 16777182 8G Linux filesyste Linux
128 2048 4095 1M BIOS boot parti BIOS Boot Partition
Disk /dev/xvdf: 16.1 GB, 16106127360 bytes, 31457280 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
LVMとして管理できるようにする
fdiskコマンドで/dev/xvdf全体を設定する
# fdisk /dev/xvdf
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0xa7d87ac1.
Command (m for help): p
Disk /dev/xvdf: 16.1 GB, 16106127360 bytes, 31457280 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
Disk label type: dos
Disk identifier: 0xa7d87ac1
[root@ip-172-31-8-150 ~]# fdisk /dev/xvdf
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0xa3a6cc9c.
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p):
Using default response p
Partition number (1-4, default 1):
First sector (2048-31457279, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-31457279, default 31457279):
Using default value 31457279
Partition 1 of type Linux and of size 15 GiB is set
Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
PV(Physical Volume)を作成する
pvcreate, pvdisplayコマンドを利用します
# pvcreate /dev/xvdf1
Physical volume "/dev/sdf1" successfully created
# pvdisplay
"/dev/sdf1" is a new physical volume of "15.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdf1
VG Name
PV Size 15.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID gIK9sh-g23t-n0oB-k4yL-pfUe-Af1u-V7CmpQ
VG(Volume Group)を作成する
vgcreate, vgdisplay, vgscanコマンドを利用します。
# vgcreate VGroup /dev/xvdf1
Volume group "VGroup" successfully created
# vgdisplay
--- Volume group ---
VG Name VGroup
System ID
Format lvm2
Metadata Areas 1
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 1
Act PV 1
VG Size 15.00 GiB
PE Size 4.00 MiB
Total PE 3839
Alloc PE / Size 0 / 0
Free PE / Size 3839 / 15.00 GiB
VG UUID zZ2Sl1-uJr0-6U61-3YBW-FeDu-nv9W-ELGxR7
# vgscan
Reading all physical volumes. This may take a while...
Found volume group "VGroup" using metadata type lvm2
LV(Logical Volume)を作成する
lvcreate, lvdisplay, lvscanコマンドを利用します。
# lvcreate --name myspace -l 100%FREE VGroup
Logical volume "myspace" created.
# lvdisplay
--- Logical volume ---
LV Path /dev/VGroup/myspace
LV Name myspace
VG Name VGroup
LV UUID wMl2eq-Mkjh-TQip-Ntdd-K6Fo-v7HX-Tsm0Vw
LV Write Access read/write
LV Creation host, time ip-172-31-8-150, 2017-01-11 02:40:46 +0000
LV Status available
# open 0
LV Size 15.00 GiB
Current LE 3839
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
# lvscan
ACTIVE '/dev/VGroup/myspace' [15.00 GiB] inherit
現在の状態を確認する
# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda 202:0 0 8G 0 disk
└─xvda1 202:1 0 8G 0 part /
xvdf 202:80 0 15G 0 disk
└─xvdf1 202:81 0 15G 0 part
└─VGroup-myspace 253:0 0 15G 0 lvm
# fdisk -l
WARNING: fdisk GPT support is currently new, and therefore in an experimental phase. Use at your own discretion.
Disk /dev/xvda: 8589 MB, 8589934592 bytes, 16777216 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
Disk label type: gpt
# Start End Size Type Name
1 4096 16777182 8G Linux filesyste Linux
128 2048 4095 1M BIOS boot parti BIOS Boot Partition
Disk /dev/xvdf: 16.1 GB, 16106127360 bytes, 31457280 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
Disk label type: dos
Disk identifier: 0xa3a6cc9c
Device Boot Start End Blocks Id System
/dev/xvdf1 2048 31457279 15727616 8e Linux LVM
Disk /dev/mapper/VGroup-myspace: 16.1 GB, 16101933056 bytes, 31449088 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
利用可能にする
ファイルシステムを作成する
# mkfs.ext4 /dev/VGroup/myspace
mke2fs 1.42.12 (29-Aug-2014)
Creating filesystem with 3931136 4k blocks and 983040 inodes
Filesystem UUID: bf4aaeb0-e7e9-43cf-b089-6f70c0a717f3
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208
Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
LV(Logical Volumne)をマウントする
# mkdir /mnt/myspace
# mount /dev/VGroup/myspace /mnt/myspace
# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 236M 68K 236M 1% /dev
tmpfs 246M 0 246M 0% /dev/shm
/dev/xvda1 7.8G 981M 6.7G 13% /
/dev/mapper/VGroup-myspace 15G 38M 14G 1% /mnt/myspace
ラベルを作成しfstabに設定する
# e2label /dev/VGroup/myspace /myspace
# cat /etc/fstab
#
LABEL=/ / ext4 defaults,noatime 1 1
LABEL=/myspace /mnt/myspace ext4 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
再起動後もmountされた状態で起動していることを確認する
LV(Logical Volume)をサイズを変更してみる
/dev/xvdfの全部を使い切っている状態なので下記の順番で試してみる
- LVサイズを縮小する
- LVサイズを元に戻す
- EBSを新規にアタッチしてLVを拡張する
LVサイズを縮小する
ブロックサイズを確認する
# blockdev --getbsz /dev/VGroup/myspace
4096
10Gに変更するのでブロック数を検出する
割り切れない場合はブロックサイズを1切り上げればよいと。
# echo "(1 * 1024 * 1024 * 1024 * 10) % 4096" | bc
0
# echo "(1 * 1024 * 1024 * 1024 * 10) / 4096" | bc
2621440
確認コマンド(e2fsck)を実行してからブロックサイズを変更(resize2fs)
# e2fsck -f /dev/VGroup/myspace
e2fsck 1.42.12 (29-Aug-2014)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/myspace: 12/983040 files (0.0% non-contiguous), 104065/3931136 blocks
# resize2fs /dev/VGroup/myspace 2621440
resize2fs 1.42.12 (29-Aug-2014)
Resizing the filesystem on /dev/VGroup/myspace to 2621440 (4k) blocks.
The filesystem on /dev/VGroup/myspace is now 2621440 (4k) blocks long.
# e2fsck /dev/VGroup/myspace
e2fsck 1.42.12 (29-Aug-2014)
/myspace: clean, 12/655360 files, 82544/2621440 blocks
LVサイズを縮小する(lvreduce)
# lvreduce -L10G /dev/VGroup/myspace
WARNING: Reducing active logical volume to 10.00 GiB
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce myspace? [y/n]: y
Size of logical volume VGroup/myspace changed from 15.00 GiB (3839 extents) to 10.00 GiB (2560 extents).
Logical volume myspace successfully resized
マウントして確認してみる
# mount /dev/VGroup/myspace /mnt/myspace/
# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 236M 68K 236M 1% /dev
tmpfs 246M 0 246M 0% /dev/shm
/dev/xvda1 7.8G 981M 6.7G 13% /
/dev/mapper/VGroup-myspace 9.8G 34M 9.2G 1% /mnt/myspace
# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda 202:0 0 8G 0 disk
└─xvda1 202:1 0 8G 0 part /
xvdf 202:80 0 15G 0 disk
└─xvdf1 202:81 0 15G 0 part
└─VGroup-myspace 253:0 0 10G 0 lvm /mnt/myspace
LVサイズを元に戻す
細かい計算は省くｗ
# umount /dev/VGroup/myspace
# lvextend -L 15G /dev/VGroup/myspace
Insufficient free space: 1280 extents needed, but only 1279 available
# lvextend -L 14.9G /dev/VGroup/myspace
Rounding size to boundary between physical extents: 14.90 GiB
Size of logical volume VGroup/myspace changed from 10.00 GiB (2560 extents) to 14.90 GiB (3815 extents).
Logical volume myspace successfully resized
LVを拡張したのでチェックし(e2fsck)、ブロック数を拡張する(resize2fs)
# e2fsck -f /dev/VGroup/myspace
e2fsck 1.42.12 (29-Aug-2014)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/myspace: 12/655360 files (0.0% non-contiguous), 82544/2621440 blocks
# resize2fs /dev/VGroup/myspace
resize2fs 1.42.12 (29-Aug-2014)
Resizing the filesystem on /dev/VGroup/myspace to 3906560 (4k) blocks.
The filesystem on /dev/VGroup/myspace is now 3906560 (4k) blocks long.
マウントして確認する
# mount /dev/VGroup/myspace /mnt/myspace
# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 236M 68K 236M 1% /dev
tmpfs 246M 0 246M 0% /dev/shm
/dev/xvda1 7.8G 981M 6.7G 13% /
/dev/mapper/VGroup-myspace 15G 38M 14G 1% /mnt/myspace
# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda 202:0 0 8G 0 disk
└─xvda1 202:1 0 8G 0 part /
xvdf 202:80 0 15G 0 disk
└─xvdf1 202:81 0 15G 0 part
└─VGroup-myspace 253:0 0 14.9G 0 lvm /mnt/myspace
EBSを新規にアタッチしてLVを拡張する
awsコンソール上からEBSを新規にアタッチするawsコンソール上から/dev/sdgとして確認できるがコマンド上だと/dev/xvdgとなる
# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda 202:0 0 8G 0 disk
└─xvda1 202:1 0 8G 0 part /
xvdf 202:80 0 15G 0 disk
└─xvdf1 202:81 0 15G 0 part
└─VGroup-myspace 253:0 0 14.9G 0 lvm /mnt/myspace
xvdg 202:96 0 7G 0 disk
# fdisk -l /dev/xvdg
Disk /dev/xvdg: 7516 MB, 7516192768 bytes, 14680064 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
パーティションを作成する。前の方の手順と同じ
# fdisk /dev/xvdg
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0x3cc33416.
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p):
Using default response p
Partition number (1-4, default 1):
First sector (2048-14680063, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-14680063, default 14680063):
Using default value 14680063
Partition 1 of type Linux and of size 7 GiB is set
Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
# fdisk -l /dev/xvdg
Disk /dev/xvdg: 7516 MB, 7516192768 bytes, 14680064 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
Disk label type: dos
Disk identifier: 0x3cc33416
Device Boot Start End Blocks Id System
/dev/xvdg1 2048 14680063 7339008 8e Linux LVM
PV(Physical Volume)の作成
# pvcreate /dev/xvdg1
Physical volume "/dev/sdg1" successfully created
# pvdisplay /dev/xvdg1
"/dev/sdg1" is a new physical volume of "7.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdg1
VG Name
PV Size 7.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID 7mj34f-MimX-sPAX-dYHg-OpqE-L0O8-xH3hjL
VG(Volume Group)を拡張する。新しいEBSぶんの7Gが増加している。
# vgextend VGroup /dev/xvdg1
Volume group "VGroup" successfully extended
# vgdisplay
--- Volume group ---
VG Name VGroup
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 5
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 0
Max PV 0
Cur PV 2
Act PV 2
VG Size 21.99 GiB
PE Size 4.00 MiB
Total PE 5630
Alloc PE / Size 3815 / 14.90 GiB
Free PE / Size 1815 / 7.09 GiB
VG UUID zZ2Sl1-uJr0-6U61-3YBW-FeDu-nv9W-ELGxR7
# vgextend VGroup /dev/xvdg1
Volume group "VGroup" successfully extended
# lvextend -L 21.5G /dev/VGroup/myspace
Size of logical volume VGroup/myspace changed from 14.90 GiB (3815 extents) to 21.50 GiB (5504 extents).
Logical volume myspace successfully resized
# e2fsck -f /dev/VGroup/myspace
e2fsck 1.42.12 (29-Aug-2014)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/myspace: 12/983040 files (0.0% non-contiguous), 104065/3906560 blocks
# resize2fs /dev/VGroup/myspace
resize2fs 1.42.12 (29-Aug-2014)
Resizing the filesystem on /dev/VGroup/myspace to 5636096 (4k) blocks.
The filesystem on /dev/VGroup/myspace is now 5636096 (4k) blocks long.
拡張できていることを確認する
# mount /dev/VGroup/myspace /mnt/myspace/
[root@ip-172-31-8-150 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 236M 76K 236M 1% /dev
tmpfs 246M 0 246M 0% /dev/shm
/dev/xvda1 7.8G 983M 6.7G 13% /
/dev/mapper/VGroup-myspace 22G 42M 20G 1% /mnt/myspace
[root@ip-172-31-8-150 ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda 202:0 0 8G 0 disk
└─xvda1 202:1 0 8G 0 part /
xvdf 202:80 0 15G 0 disk
└─xvdf1 202:81 0 15G 0 part
└─VGroup-myspace 253:0 0 21.5G 0 lvm /mnt/myspace
xvdg 202:96 0 7G 0 disk
└─xvdg1 202:97 0 7G 0 part
└─VGroup-myspace 253:0 0 21.5G 0 lvm /mnt/myspace