system2之：4-LVM逻辑卷管理

LVM有扩容功能，无容错功能

物理卷：

[root@localhost ~]# pvscan

PV /dev/sda2 VG VolGroup lvm2 [19.51 GiB / 0 free]

Total: 1 [19.51 GiB] / in use: 1 [19.51 GiB] / in no VG: 0 [0 ]

[root@localhost ~]# pvcreate /dev/sd[bcd]

把bcd磁盘都设置为物理卷

Writing physical volume data to disk "/dev/sdb"

Physical volume "/dev/sdb" successfully created

Writing physical volume data to disk "/dev/sdc"

Physical volume "/dev/sdc" successfully created

Writing physical volume data to disk "/dev/sdd"

Physical volume "/dev/sdd" successfully created

[root@localhost ~]#

[root@localhost ~]# pvdisplay
显示物理卷信息

--- Physical volume --- 原来就有的

PV Name               /dev/sda2

VG Name               VolGroup

PV Size               19.51 GiB / not usable 3.00 MiB

Allocatable           yes (but full)

PE Size               4.00 MiB

Total PE              4994

Free PE               0

Allocated PE          4994

PV UUID Pap7Ba-SA2w-3Ymo-tLFS-QG8H-bPsl-Tf04iJ

以下是刚分配的

"/dev/sdb" is a new physical volume of "10.00 GiB"

--- NEW Physical volume ---

PV Name               /dev/sdb

VG Name

PV Size               10.00 GiB

Allocatable           NO

可以分配的

PE Size               0

Total PE              0

Free PE               0

Allocated PE          0

PV UUID               3XM4hj-w10O-YgTi-xEKW-05tA-dAZr-Ql3Ica

"/dev/sdc" is a new physical volume of "10.00 GiB"

--- NEW Physical volume ---

PV Name               /dev/sdc

VG Name

PV Size               10.00 GiB

Allocatable           NO

PE Size               0

Total PE              0

Free PE               0

Allocated PE          0

PV UUID               3Qc3sW-Hol0-ekui-2CbJ-ECuh-X3ao-Y0fGr5

"/dev/sdd" is a new physical volume of "10.00 GiB"

--- NEW Physical volume ---

PV Name               /dev/sdd

VG Name

PV Size               10.00 GiB

Allocatable           NO

PE Size               0

Total PE              0

Free PE               0

Allocated PE          0

PV UUID cTsZmX-mV5F-wYm2-l5O8-0pSD-otdT-rbaG5x

[root@localhost ~]# pvremove /dev/sdd

Labels on physical volume "/dev/sdd" successfully wiped

[root@localhost ~]# pvscan
PV /dev/sda2   VG VolGroup        lvm2 [19.51 GiB / 0    free]
PV /dev/sdb                       lvm2 [10.00 GiB]
PV /dev/sdc                       lvm2 [10.00 GiB]
Total: 3 [39.51 GiB] / in use: 1 [19.51 GiB] / in no VG: 2 [20.00 GiB]
[root@localhost ~]#

卷组：

[root@localhost ~]# vgscan

Reading all physical volumes. This may take a while...

Found volume group "VolGroup" using metadata type lvm2

[root@localhost ~]# vgcreate aligege /dev/sd[bc]
两种创建方法

[root@localhost ~]#
vgcreate aligege /dev/sdb /dev/sdc

Volume group "aligege" successfully created

[root@localhost ~]# vgscan

Reading all physical volumes. This may take a while...

Found volume group "aligege" using metadata type lvm2

Found volume group "VolGroup" using metadata type lvm2

[root@localhost ~]#

[root@localhost ~]# vgdisplay

--- Volume group ---

VG Name               aligege

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               19.99 GiB

PE Size               4.00 MiB

Total PE              5118

Alloc PE / Size       0 / 0

Free PE / Size       5118 / 19.99 GiB

VG UUID               U1swqi-DDR9-0jHR-1Lh5-yq6c-iav6-Wtj185

--- Volume group ---

VG Name               VolGroup

System ID

Format                lvm2

Metadata Areas        1

Metadata Sequence No 3

VG Access             read/write

VG Status             resizable

MAX LV                0

Cur LV                2

Open LV               2

Max PV                0

Cur PV                1

Act PV                1

VG Size               19.51 GiB

PE Size               4.00 MiB
卷组分配后PE也就分配了，之前没有

Total PE              4994

Alloc PE / Size       4994 / 19.51 GiB

Free PE / Size       0 / 0

VG UUID               j3HHZT-spWa-PQtD-mA3c-hNNK-t0gk-QfkENs

[root@localhost ~]#

[root@localhost ~]# vgremove aligege

Volume group "aligege" successfully removed

[root@localhost ~]#

逻辑卷操作：

[root@localhost ~]# lvcreate -L 15G -n HR-cost aligege

Logical volume "HR-cost" created

[root@localhost ~]# lvdisplay

--- Logical volume ---

LV Path                /dev/aligege/HR-cost

LV Name                HR-cost

VG Name                aligege

LV UUID                HlViMr-3lCN-JAK3-muyt-y1Js-2CWW-G3JmaB

LV Write Access        read/write

LV Creation host, time localhost.localdomain, 2013-07-20 19:01:20 +0800

LV Status              available

# open                 0

LV Size                15.00 GiB

Current LE             3840

Segments               2

Allocation             inherit

Read ahead sectors     auto

- currently set to     256

Block device           253:2

--- Logical volume ---

LV Path                /dev/VolGroup/lv_root

LV Name                lv_root

VG Name                VolGroup

LV UUID                APrXHZ-xATh-g51W-7Hpc-UQYL-50oM-xpY7py

LV Write Access        read/write

LV Creation host, time localhost.localdomain, 2013-07-18 21:12:47 +0800

LV Status              available

# open                 1

LV Size                17.48 GiB

Current LE             4474

Segments               1

Allocation             inherit

Read ahead sectors     auto

- currently set to     256

Block device           253:0

--- Logical volume ---

LV Path                /dev/VolGroup/lv_swap

LV Name                lv_swap

VG Name                VolGroup

LV UUID                wG2cMD-ZHph-bgXH-3H1k-x04e-YKFi-bazXir

LV Write Access        read/write

LV Creation host, time localhost.localdomain, 2013-07-18 21:12:51 +0800

LV Status              available

# open                 1

LV Size                2.03 Gi
B

Current LE             520

Segments               1

Allocation             inherit

Read ahead sectors     auto

- currently set to     256

Block device           253:1

[root@localhost ~]#

格式化

[root@localhost ~]# mkfs.ext4 /dev/aligege/HR-cost

挂载使用

[root@localhost ~]# mkdir /HR

[root@localhost ~]# mount /dev/aligege/HR-cost /HR

[root@localhost ~]# df -Th

文件系统    类型      容量已用可用已用%% 挂载点

/dev/mapper/VolGroup-lv_root

              ext4     18G 1.8G   15G 11% /

tmpfs        tmpfs    516M     0 516M   0% /dev/shm

/dev/sda1     ext4    485M   31M 429M   7% /boot

/dev/mapper/aligege-HR--cost

              ext4     15G 166M   14G   2% /HR

[root@localhost ~]#

也可以使用分区，这里直接用的是磁盘
，道理是差不多的。

扩容：

vgextend 卷组名字磁盘物理卷名字

[root@localhost ~]# pvcreate /dev/sd[defg]

Writing physical volume data to disk "/dev/sdd"

Physical volume "/dev/sdd" successfully created

Writing physical volume data to disk "/dev/sde"

Physical volume "/dev/sde" successfully created

Writing physical volume data to disk "/dev/sdf"

Physical volume "/dev/sdf" successfully created

Writing physical volume data to disk "/dev/sdg"

Physical volume "/dev/sdg" successfully created

[root@localhost ~]# vgextend aligege /dev/sd[defg]

Volume group "aligege" successfully extended

[root@localhost ~]# vgdisplay

--- Volume group ---

VG Name               aligege

System ID

Format                lvm2

Metadata Areas        6

Metadata Sequence No 3

VG Access             read/write

VG Status             resizable

MAX LV                0

Cur LV                1

Open LV               1

Max PV                0

Cur PV                6

Act PV                6

VG Size               59.98 GiB
   扩容成功

PE Size               4.00 MiB

Total PE              15354

Alloc PE / Size       3840 / 15.00 GiB

Free PE / Size       11514 / 44.98 GiB

VG UUID               sDhCUJ-XsJf-Yt0B-bKSt-kbF9-XU09-8jrzjT

[root@localhost ~]# lvextend -L +20G /dev/aligege/HR-cost

Extending logical volume HR-cost to 35.00 GiB

Logical volume HR-cost successfully resized

[root@localhost ~]#

[root@localhost ~]# df -Th

文件系统    类型      容量已用可用已用%% 挂载点

/dev/mapper/VolGroup-lv_root

              ext4     18G 1.8G   15G 11% /

tmpfs        tmpfs    516M     0 516M   0% /dev/shm

/dev/sda1     ext4    485M   31M 429M   7% /boot

/dev/mapper/aligege-HR--cost

              ext4     15G 166M   14G   2% /HR

[root@localhost ~]#

这里还是15G？？为什么？

要
重新识别一下：

[root@localhost ~]#
resize2fs /dev/aligege/HR-cost

resize2fs 1.41.12 (17-May-2010)

Filesystem at /dev/aligege/HR-cost is mounted on /HR; on-line resizing required

old desc_blocks = 1, new_desc_blocks = 3

Performing an on-line resize of /dev/aligege/HR-cost to 9175040 (4k) blocks.

The filesystem on /dev/aligege/HR-cost is now 9175040 blocks long.

[root@localhost ~]#

[root@localhost ~]# df -Th

文件系统    类型      容量已用可用已用%% 挂载点

/dev/mapper/VolGroup-lv_root

              ext4     18G 1.8G   15G 11% /

tmpfs        tmpfs    516M     0 516M   0% /dev/shm

/dev/sda1     ext4    485M   31M 429M   7% /boot

/dev/mapper/aligege-HR--cost

              ext4     35G 173M   33G   1% /HR

[root@localhost ~]#

这样就变成35G了。

system2之：4-LVM逻辑卷管理

[root@localhost ~]# umount /dev/aligege/HR-cost

[root@localhost ~]# df -Th

文件系统    类型      容量已用可用已用%% 挂载点

/dev/mapper/VolGroup-lv_root

              ext4     18G 1.8G   15G 11% /

tmpfs        tmpfs    516M     0 516M   0% /dev/shm

/dev/sda1     ext4    485M   31M 429M   7% /boot

[root@localhost ~]# lvremove /dev/aligege/HR-cost

Do you really want to remove active logical volume HR-cost? [y/n]: y

Logical volume "HR-cost" successfully removed

[root@localhost ~]# vgremove /dev/aligege

Volume group "aligege" successfully removed

[root@localhost ~]# pvremove /dev/sdb[bcdefg]

Physical Volume /dev/sdb[bcdefg] not found

[root@localhost ~]# pvremove /dev/sd[bcdefg]

Labels on physical volume "/dev/sdb" successfully wiped

Labels on physical volume "/dev/sdc" successfully wiped

Labels on physical volume "/dev/sdd" successfully wiped

Labels on physical volume "/dev/sde" successfully wiped

Labels on physical volume "/dev/sdf" successfully wiped

Labels on physical volume "/dev/sdg" successfully wiped

[root@localhost ~]#

5，6可以做也可以不做，6是相对于分区来说的，直接在磁盘进行不需要。

PV--》VG--》LV这个过程可以形象的跟建设一个公司筹集资金，再计划资金的使用一样。如下图：

这样理解起来就简单很多了。

安装系统的时候，红帽默认采用lvm方式

boot分区不能创建LVM

LVM的优点是当/分区空间不足的时候还可以扩容。

RAID

独立磁盘冗余数组
（
RAID,RedundantArray ofIndependentDisks
），旧称
廉价磁盘冗余数组
（
RAID,RedundantArray ofInexpensiveDisks
），简称
硬盘阵列
。其基本思想就是把多个相对便宜的硬盘组合起来，成为一个硬盘阵列组，使性能达到甚至超过一个价格昂贵、容量巨大的硬盘。

详细介绍参看：
http://zh.wikipedia.org/wiki/RAID

RAID卡

图：

在服务器里，硬件RAID用的比较多。

RAID 0：条带卷（
）

将多个磁盘合并成一个大的磁盘，不具有冗余，并行
I/O
，速度最快。

只需要2块以上的硬盘即可，成本低，可以提高整个磁盘的性能和吞吐量，读写速度快。（没有容错功能）

RAID 1：镜像卷

50%空间利用率

有容错功能

坏一块另外一块可以顶上，一般拿两块磁盘做镜像卷
（两块磁盘一模一样）

RAID 4：带校验的条带

都是放到一块磁盘上的，

RAID 5

是一种储存性能、数据安全和存储成本兼顾的存储解决方案。它使用的是Disk Striping（硬盘分区）技术。RAID 5 至少需要三颗硬盘

（n-1）/n利用率

有容错功能，最多可以坏一块

RAID 6

与RAID 5相比，
RAID 6
增加了第二个独立的奇偶校验信息块
，所以最多可以坏两块。
至少四块，利用率（n-1）/n

RAID 10：镜像+条带

4块磁盘，有容错功能，最多可以坏2块磁盘
（利用率50%）

RAID 10/01:细分为RAID 1+0或RAID 0+1

性能上，RAID 0+1比RAID 1+0有着更快的读写速度。

可靠性上，当RAID 1+0有一个硬盘受损，其余三个硬盘会继续运作。RAID 0+1 只要有一个硬盘受损，同组RAID 0的另一只硬盘亦会停止运作，只剩下两个硬盘运作，可靠性较低。

因此，RAID 10远较RAID 01常用，零售
主板
绝大部份支持RAID 0/1/5/10，但不支持RAID 01。

硬RAID可以直接通过RAID卡恢复，软raid则要经过cpu

这几个一般选RAID6，最多可以坏两块。

mdadm命令

用途：创建，修改监控RAID阵列

1。新建raid5卷，使用4块磁盘作raid5，1块磁盘作热备

mdadm -C /dev/md1 -l5 -n4 -x1 /dev/sd[efghi] 会自动抽取一块做热备

2。格式化raid5设备

mkfs.ext3 /dev/md1

3.挂载使用
mkdir /music
mount /dev/md1 /music

4.自动挂载功能，修改/etc/fstab文件，添加

/dev/md1 /music ext3 defaults 0 0

让其中的一块失效，然后看raid5是否能够继续使用

mdadm /dev/md1 -f /dev/sde

使用cat /proc/mdstat命令查看修复过程

删除有问题的磁盘，添加一个好的磁盘作热备，要求磁盘>容量一致

mdadm /dev/md1 -r /dev/sde -a /dev/sdk

=======

[root@localhost ~]# cat /proc/mdstat 查看raid的构建过程

Personalities : [raid6] [raid5] [raid4]

md5 : active raid5 sde[5] sdf[4](S) sdd[2] sdc[1] sdb[0]

      3144192 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/3] [UUU_]

      [=============>.......] recovery = 68.5% (719232/1048064) finish=0.0min speed=143846K/sec



unused devices: <none>

[root@localhost ~]# cat /proc/mdstat

Personalities : [raid6] [raid5] [raid4]

md5 : active raid5 sde[5] sdf[4](S) sdd[2] sdc[1] sdb[0]

      3144192 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]



unused devices: <none>

[root@localhost ~]#

[UUUU]---》表示4个use：在使用

做raid5最好五个容量都是一样的，一个厂家

[root@localhost ~]#
mdadm -D /dev/md5

/dev/md5:

        Version : 1.2

Creation Time : Sun Jul 21 01:21:33 2013

     Raid Level : raid5

     Array Size : 3144192 (3.00 GiB 3.22 GB)

Used Dev Size : 1048064 (1023.67 MiB 1073.22 MB)

   Raid Devices : 4

Total Devices : 5

    Persistence : Superblock is persistent

Update Time : Sun Jul 21 01:21:44 2013

State : clean

Active Devices : 4

Working Devices : 5

Failed Devices : 0

Spare Devices : 1

Layout : left-symmetric

Chunk Size : 512K

Name : localhost.localdomain:5 (local to host localhost.localdomain)

           UUID : 4e379d32:20a354d7:c6baee5e:68bd25cb

         Events : 18

                    主编号   副编号

    Number   Major   Minor   RaidDevice State

       0       8       16        0      active sync   /dev/sdb

       1       8       32        1      active sync   /dev/sdc

       2       8       48        2      active sync   /dev/sdd

       5       8       64        3      active sync   /dev/sde

4 8 80 - spare /dev/sdf
热备（spare）

[root@localhost ~]#

[root@localhost ~]# mdadm -Ds

ARRAY /dev/md5 metadata=1.2 spares=1 name=localhost.localdomain:5 UUID=4e379d32:20a354d7:c6baee5e:68bd25cb

[root@localhost ~]#

[root@localhost ~]# mdadm /dev/md5 -f /dev/sdd 损坏一块

mdadm: set /dev/sdd faulty in /dev/md5

[root@localhost ~]# cat /proc/mdstat

Personalities : [raid6] [raid5] [raid4]

md5 : active raid5 sde[5] sdf[4] sdd[2](F) sdc[1] sdb[0]

      3144192 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/3]
[UU_U]

      [=>...................] recovery = 9.5% (100480/1048064) finish=0.1min speed=100480K/sec



unused devices: <none>

[root@localhost ~]#

[root@localhost ~]# cat /proc/mdstat

Personalities : [raid6] [raid5] [raid4]

md5 : active raid5 sde[5] sdf[4] sdd[2](F) sdc[1] sdb[0]

      3144192 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4]
[UUUU]
一会儿又被备用的修复了



unused devices: <none>

[root@localhost ~]#

[root@localhost ~]# mdadm /dev/md5 -f /dev/sde 再毁坏一块

mdadm: set /dev/sde faulty in /dev/md5

[root@localhost ~]# cat /proc/mdstat

Personalities : [raid6] [raid5] [raid4]

md5 : active raid5 sde[5](F) sdf[4] sdd[2](F) sdc[1] sdb[0]

      3144192 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/3] [UUU_]



unused devices: <none>

[root@localhost ~]# cd /file 但是还能访问，有容错功能

[root@localhost file]# ls

lost+found

[root@localhost file]# mkdir haha

[root@localhost file]# ls

haha lost+found

[root@localhost file]#

[root@localhost file]# mdadm -D /dev/md5

Number   Major   Minor   RaidDevice State

       0       8       16        0      active sync   /dev/sdb

       1       8       32        1      active sync   /dev/sdc

       4       8       80        2      active sync   /dev/sdf

       3       0        0        3      removed

2 8 48 - faulty spare /dev/sdd

5 8 64 - faulty spare /dev/sde

[root@localhost file]# mdadm /dev/md5 -r /dev/sd[de]

mdadm: hot removed /dev/sdd from /dev/md5 热移除

mdadm: hot removed /dev/sde from /dev/md5

[root@localhost file]#

[root@localhost file]# mdadm -D /dev/md5

[root@localhost file]# mdadm /dev/md5 -a /dev/sd[h] 新增

mdadm: added /dev/sdh

[root@localhost file]# mdadm /dev/md5 -a /dev/sd[g]

mdadm: added /dev/sdg

[root@localhost file]# mdadm -D /dev/md5

/dev/md5:

        Version : 1.2

Creation Time : Sun Jul 21 01:21:33 2013

     Raid Level : raid5

     Array Size : 3144192 (3.00 GiB 3.22 GB)

Used Dev Size : 1048064 (1023.67 MiB 1073.22 MB)

   Raid Devices : 4

Total Devices : 5

    Persistence : Superblock is persistent

Update Time : Sun Jul 21 01:50:03 2013

State : clean

Active Devices : 4

Working Devices : 5

Failed Devices : 0

Spare Devices : 1

Layout : left-symmetric

Chunk Size : 512K

Name : localhost.localdomain:5 (local to host localhost.localdomain)

UUID : 4e379d32:20a354d7:c6baee5e:68bd25cb

Events : 72

Number   Major   Minor   RaidDevice State

       0       8       16        0      active sync   /dev/sdb

       1       8       32        1      active sync   /dev/sdc

       4       8       80        2      active sync   /dev/sdf

       5       8      112        3      active sync   /dev/sdh

6 8 96 - spare /dev/sdg 把最后建的当备用

[root@localhost file]#

system2之：4-LVM逻辑卷管理

先将磁盘做成RAID再做成pv，然后再化LVM（物理卷不一定是硬盘，也可以是 RAID）

因为RAID有容错功能，pv能够扩容，二者结合性能更好。

秒客网

system2之：4-LVM逻辑卷管理

相关文章