Xen或者KVM线上主机的磁盘空间不足，需要增大硬盘，并且不能重启，这时候就需要热添加以扩充磁盘空间
说明：Xen和KVM主机都为CentOS 6.4 guest磁盘为lvm格式
先来说Xen吧，操作都一样的，虚拟机上测试
Xen的guest主机扩充根分区：
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# xm list #test2主机增大磁盘空间
Name ID Mem VCPUs State Time(s)
Domain-0 0 1024 4 r----- 80.8
test2 1 768 4 -b---- 25.8
# qemu-img info test2.qcow2 #现在为10G的磁盘
image: test2.qcow2
file
format
: raw
virtual size: 10G (10739318784 bytes)
disk size: 1.5G
# qemu-img create -f qcow2 -o size=5G,preallocation=metadata /data/testadd.qcow2 #新建一块5G的磁盘
Formatting
'/data/testadd.qcow2'
,
fmt
=qcow2 size=5368709120 encryption=off
cluster_size=65536 preallocation=
'metadata'
#防止出错，把preallocation=metadata去掉，或者qemu-img create -f raw /data/testadd.img 5G
# qemu-img info testadd.qcow2 #查看新建的磁盘
image: testadd.qcow2
file
format
: qcow2
virtual size: 5.0G (5368709120 bytes)
disk size: 912K
cluster_size: 65536
# virsh attach-disk test2 /data/testadd.qcow2 xvdb --cache=writeback --subdriver=qcow2 #对test2主机进行添加，xvdb
Disk attached successfully
# vim test2 #修改guest的配置文件，添加xvdb
name =
"test2"
memory =
"768"
disk = [
"file:/data/test2.qcow2,xvda,w"
,
"file:/data/testadd.qcow2,xvdb,w"
]
vif = [
"bridge=br0"
]
vcpus = 4
on_reboot =
"restart"
on_crash =
"destroy"
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接下来就是进入guest内的操作，先对其分区
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# fdisk -l ＃查看有没有刚添加的xvdb
Disk
/dev/xvdb
: 5369 MB, 5369757696 bytes
255 heads, 63 sectors
/track
, 652 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
# fdisk /dev/xvdb #进行分区，lvm格式
Command (m
for
help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-652, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-652, default 652):
Using default value 652
Command (m
for
help): t
Selected partition 1
Hex code (
type
L to list codes): 8e
Changed system
type
of partition 1 to 8e (Linux LVM)
Command (m
for
help): p
Disk
/dev/xvdb
: 5369 MB, 5369757696 bytes
255 heads, 63 sectors
/track
, 652 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: 0xb1ef0943
Device Boot Start End Blocks Id System
/dev/xvdb1
1 652 5237158+ 8e Linux LVM
Command (m
for
help): w
The partition table has been altered!
Calling ioctl() to re-
read
partition table.
Syncing disks.
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lvm磁盘分区
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[root@localhost ~]
# partx -a /dev/xvdb
BLKPG: Device or resource busy
error adding partition 1
[root@localhost ~]
# kpartx /dev/xvdb
xvdb1 : 0 10474317
/dev/xvdb
63
[root@localhost ~]
# partx -a /dev/xvdb1 /dev/xvdb
[root@localhost ~]
# pvcreate /dev/xvdb1
Physical volume
"/dev/xvdb1"
successfully created
[root@localhost ~]
# vgs #现在为10G的磁盘
VG
#PV #LV #SN Attr VSize VFree
VolGroup 1 2 0 wz--n- 9.51g 0
[root@localhost ~]
# vgextend VolGroup /dev/xvdb1
Volume group
"VolGroup"
successfully extended
[root@localhost ~]
# vgs #增大了5G的空间
VG
#PV #LV #SN Attr VSize VFree
VolGroup 2 2 0 wz--n- 14.50g 4.99g
[root@localhost ~]
# lvs
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
lv_root VolGroup -wi-ao--- 8.54g
lv_swap VolGroup -wi-ao--- 992.00m
[root@localhost ~]
# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
8.5G 695M 7.3G 9% /
tmpfs 371M 0 371M 0%
/dev/shm
/dev/xvda1
485M 32M 429M 7%
/boot
[root@localhost ~]
# lvextend -l +100%FREE /dev/VolGroup/lv_root
Extending logical volume lv_root to 13.53 GiB
Logical volume lv_root successfully resized
[root@localhost ~]
# resize2fs /dev/VolGroup/lv_root
resize2fs 1.41.12 (17-May-2010)
Filesystem at
/dev/VolGroup/lv_root
is mounted on /; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 1
Performing an on-line resize of
/dev/VolGroup/lv_root
to 3547136 (4k) blocks.
The filesystem on
/dev/VolGroup/lv_root
is now 3547136 blocks long.
[root@localhost ~]
# df -h #磁盘增加好了
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
14G 698M 12G 6% /
tmpfs 371M 0 371M 0%
/dev/shm
/dev/xvda1
485M 32M 429M 7%
/boot
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KVM的guest热扩充磁盘空间
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[root@localhost ~]
# virsh list
Id Name State
----------------------------------------------------
1 bbotte running
# qemu-img info bbotte.qcow2
image: bbotte.qcow2
file
format
: qcow2
virtual size: 10G (10737418240 bytes)
disk size: 1.3G
cluster_size: 65536
# qemu-img create -f qcow2 -o size=5G,preallocation=metadata /var/kvm/bbotteadd.qcow2
Formatting
'/var/kvm/bbotteadd.qcow2'
,
fmt
=qcow2 size=5368709120 encryption=off cluster_size=65536 preallocation=
'metadata'
#防止出错，把preallocation=metadata去掉，或者qemu-img create -f raw /var/kvm/bbotteadd.img 5G
# virsh attach-disk bbotte /var/kvm/bbotteadd.qcow2 vdb --cache=writeback --subdriver=qcow2
Disk attached successfully
# virsh edit bbotte
<devices>
<emulator>
/usr/libexec/qemu-kvm
<
/emulator
>
<disk
type
=
'file'
device=
'disk'
>
<driver name=
'qemu'
type
=
'qcow2'
cache=
'writeback'
/>
<
source
file
=
'/var/kvm/bbotte.qcow2'
/>
<target dev=
'vda'
bus=
'virtio'
/>
<address
type
=
'pci'
domain=
'0x0000'
bus=
'0x00'
slot=
'0x05'
function
=
'0x0'
/>
<
/disk
>
##下面为添加的磁盘文件
<disk
type
=
'file'
device=
'disk'
>
<driver name=
'qemu'
type
=
'qcow2'
cache=
'writeback'
/>
<
source
file
=
'/var/kvm/bbotteadd.qcow2'
/>
#指定路径
<target dev=
'vdb'
bus=
'virtio'
/>
#指定磁盘名称vdb
<address
type
=
'pci'
domain=
'0x0000'
bus=
'0x00'
slot=
'0x07'
function
=
'0x0'
/>
#slot和其他的设备序列不要相同，如果相同，保存的时候会有提示
<
/disk
>
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到guest主机里面，会看到如下提示
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# pci 0000:00:07.0: BAR 1: assigned [mem 0x30000000-0x30000fff]
pci 0000:00:07.0: BAR 1:
set
to [mem 0x30000000-0x30000fff] (PCI address [0x30000000-0x30000fff]
pci 0000:00:07.0: BAR 0: assigned [io 0x1000-0x103f]
pci 0000:00:07.0: BAR 0:
set
to [io 0x1000-0x103f] (PCI address [0x1000-0x103f]
pci 0000:00:00.0: no hotplug settings from platform
pci 0000:00:00.0: using default PCI settings
pci 0000:00:01.0: no hotplug settings from platform
pci 0000:00:01.0: using default PCI settings
ata_piix 0000:00:01.1: no hotplug settings from platform
ata_piix 0000:00:01.1: using default PCI settings
piix4_smbus 0000:00:01.3: no hotplug settings from platform
piix4_smbus 0000:00:01.3: using default PCI settings
virtio-pci 0000:00:03.0: no hotplug settings from platform
virtio-pci 0000:00:03.0: using default PCI settings
uhci_hcd 0000:00:04.0: no hotplug settings from platform
uhci_hcd 0000:00:04.0: using default PCI settings
uhci_hcd 0000:00:04.1: no hotplug settings from platform
uhci_hcd 0000:00:04.1: using default PCI settings
uhci_hcd 0000:00:04.2: no hotplug settings from platform
uhci_hcd 0000:00:04.2: using default PCI settings
ehci_hcd 0000:00:04.7: no hotplug settings from platform
ehci_hcd 0000:00:04.7: using default PCI settings
virtio-pci 0000:00:05.0: no hotplug settings from platform
virtio-pci 0000:00:05.0: using default PCI settings
virtio-pci 0000:00:06.0: no hotplug settings from platform
virtio-pci 0000:00:06.0: using default PCI settings
pci 0000:00:07.0: no hotplug settings from platform
pci 0000:00:07.0: using default PCI settings
virtio-pci 0000:00:07.0: enabling device (0000 -> 0003)
virtio-pci 0000:00:07.0: PCI INT A -> Link[LNKC] -> GSI 11 (level, high) -> IRQ 11
vdb: unknown partition table
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进行磁盘扩充
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# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
8.4G 918M 7.1G 12% /
tmpfs 372M 0 372M 0%
/dev/shm
/dev/vda1
485M 32M 428M 7%
/boot
# fdisk -l
Disk
/dev/vdb
: 5368 MB, 5368709120 bytes
16 heads, 63 sectors
/track
, 10402 cylinders
Units = cylinders of 1008 * 512 = 516096 bytes
Sector size (logical
/physical
): 512 bytes / 512 bytes
I
/O
size (minimum
/optimal
): 512 bytes / 512 bytes
Disk identifier: 0x00000000
[root@localhost ~]
# lvs
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
lv_root VolGroup -wi-ao---- 8.51g
lv_swap VolGroup -wi-ao---- 1.00g
[root@localhost ~]
# vgextend VolGroup /dev/vdb
No physical volume label
read
from
/dev/vdb
Physical volume
/dev/vdb
not found
Physical volume
"/dev/vdb"
successfully created
Volume group
"VolGroup"
successfully extended
[root@localhost ~]
# lvextend -l +100%FREE /dev/mapper/VolGroup-lv_root
Extending logical volume lv_root to 13.50 GiB
Logical volume lv_root successfully resized
[root@localhost ~]
# resize2fs /dev/mapper/VolGroup-lv_root
resize2fs 1.41.12 (17-May-2010)
Filesystem at
/dev/mapper/VolGroup-lv_root
is mounted on /; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 1
Performing an on-line resize of
/dev/mapper/VolGroup-lv_root
to 3539968 (4k) blocks.
The filesystem on
/dev/mapper/VolGroup-lv_root
is now 3539968 blocks long.
[root@localhost ~]
# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
14G 920M 12G 8% /
tmpfs 372M 0 372M 0%
/dev/shm
/dev/vda1
485M 32M 428M 7%
/boot
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扩充磁盘有危险，请结合自己的环境及设置调整，先在测试机操作
重启方式添加磁盘文件扩充磁盘空间：
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# qemu-img create -f qcow2 -o size=100G,preallocation=metadata /var/xen/centos3.qcow2
# qemu-img info centos3.qcow2
image: centos3.qcow2
file
format
: qcow2
virtual size: 100G (107374182400 bytes)
disk size: 49G
cluster_size: 65536
#已经是100G空间的guest主机，下面再增大100G空间
# qemu-img resize centos3.qcow2 +100G #增加100G空间
# qemu-img info centos3.qcow2
image: centos3.qcow2
file
format
: qcow2
virtual size: 200G (214748364800 bytes)
disk size: 49G
cluster_size: 65536
#img格式增大硬盘容量
dd
if
=
/dev/zero
bs=8k count=125000 >>
/data/centos65
.img
125000+0 records
in
125000+0 records out
1024000000 bytes (1.0 GB) copied, 14.1461 s, 72.4 MB
/s
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然后进入guest主机，如上Xen主机扩充磁盘的方式进行添加。
也可以进入guest主机，把新添加的磁盘文件分区后新建文件夹，进行挂载
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# fdisk -l
# fdisk /dev/xvdb
# partx -a /dev/xvdb
BLKPG: Device or resource busy
error adding partition 1
# kpartx /dev/xvdb
xvdb1 : 0 4294961622
/dev/xvdb
63
# partx -a /dev/xvdb1 /dev/xvdb
# mkfs.ext4 /dev/xvdb1
# mkdir /data
# vim /etc/fstab
/dev/xvdb1
/data
ext4 defaults 0 0
# mount -a
# df -h
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另：qcow2文件只能增大不能减小，lvm磁盘格式没有ext的速度快
增大磁盘容量方法是灵活的，谨慎操作
本文转自 bbotte 51CTO博客，原文链接：http://blog.51cto.com/bbotte/1630880，如需转载请自行联系原作者
