centos5.5软件raid1+lvm逻辑卷标管理总结

上次有台机器用来做了samba服务器，感觉软件很重要所以想了想在找了一块80g的硬盘做了raid1镜像，花费了一天的时间一边实验一边总结,自己做个笔记以免以后忘记。

1.[root@zh888 ~]# rpm -q mdadm//先查询是否有mdadm的软件包。

mdadm-2.6.9-3.el5//说明有了，如果没有请用yum -y install来安装即可。

2.[root@zh888 ~]# fdisk -l//查看分区

Disk /dev/hda: 40.0 GB, 40020664320 bytes

255 heads, 63 sectors/track, 4865 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System

/dev/hda1 * 1 13 104391 83 Linux

/dev/hda2 14 144 1052257+ 82 Linux swap / Solaris

/dev/hda3 145 4865 37921432+ 83 Linux

Disk /dev/hdb: 80.0 GB, 80026361856 bytes

16 heads, 63 sectors/track, 155061 cylinders

Units = cylinders of 1008 * 512 = 516096 bytes

Disk /dev/hdb doesn't contain a valid partition table

Disk /dev/hdd: 81.9 GB, 81964302336 bytes

16 heads, 63 sectors/track, 158816 cylinders

Units = cylinders of 1008 * 512 = 516096 bytes

Disk /dev/hdd doesn't contain a valid partition table

[root@zh888 ~]# fdisk /dev/hdb//分区为fd类型/dev/hdd也是同样的操作。

Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel

Building a new DOS disklabel. Changes will remain in memory only,

until you decide to write them. After that, of course, the previous

content won't be recoverable.

The number of cylinders for this disk is set to 155061.

There is nothing wrong with that, but this is larger than 1024,

and could in certain setups cause problems with:

1) software that runs at boot time (e.g., old versions of LILO)

2) booting and partitioning software from other OSs

(e.g., DOS FDISK, OS/2 FDISK)

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

Command (m for help): n//new新分区

Command action

e extended

p primary partition (1-4)

p//主分区

Partition number (1-4): 1//第一个分区

First cylinder (1-155061, default 1): 回车

Using default value 1

Last cylinder or +size or +sizeM or +sizeK (1-155061, default 155061): 回车

Using default value 155061

Command (m for help): t//type类型

Selected partition 1

Hex code (type L to list codes): fd//fd类型

Changed system type of partition 1 to fd (Linux raid autodetect)

Command (m for help): w//保存写入

The partition table has been altered!

Calling ioctl() to re-read partition table.

Syncing disks.

3.[root@zh888 ~]# fdisk -l//在次查看硬盘类型

Disk /dev/hda: 40.0 GB, 40020664320 bytes

255 heads, 63 sectors/track, 4865 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System

/dev/hda1 * 1 13 104391 83 Linux

/dev/hda2 14 144 1052257+ 82 Linux swap / Solaris

/dev/hda3 145 4865 37921432+ 83 Linux

Disk /dev/hdb: 80.0 GB, 80026361856 bytes

16 heads, 63 sectors/track, 155061 cylinders

Units = cylinders of 1008 * 512 = 516096 bytes

Device Boot Start End Blocks Id System

/dev/hdb1 1 155061 78150712+ fd Linux raid autodetect//已经为linux raid了

Disk /dev/hdd: 81.9 GB, 81964302336 bytes

16 heads, 63 sectors/track, 158816 cylinders

Units = cylinders of 1008 * 512 = 516096 bytes

Device Boot Start End Blocks Id System

/dev/hdd1 1 158816 80043232+ fd Linux raid autodetect

4.[root@zh888 ~]#mdadm --create --verbose /dev/md0 --level=1 --raid-devices=2 /dev/hdb1 /dev/hdd1 //创建raid1命令可以用简写如下：

mdadm: array /dev/md0 started.

//[root@zh888 ~]#mdadm -C /dev/md0 -l1 -n2 -c128 /dev/hd[bd]也可以用这种方法创建。

mdadm: array /dev/md0 started.

5.[root@zh888 ~]# echo DEVICE /dev/hd[bd]>/etc/mdadm.conf

或cp /usr/share/doc/mdadm-2.5.4/mdadm.conf-example /etc/mdadm.conf

或echo DEVICE /dev/hd[bd]1 >>/etc/mdadm.conf

6.[root@zh888 ~]# mdadm --detail --scan>>/etc/mdadm.conf

或mdadm -Ds >>/etc/mdadm.conf

7.[root@zh888 ~]# cat /etc/mdadm.conf//查看mdadm.conf文件如下：

DEVICE /dev/hdb /dev/hdd

ARRAY /dev/md0 level=raid1 num-devices=2 metadata=0.90 UUID=57319c2a:090717a6:92042ec3:e00720c4

8.[root@zh888 ~]# mkfs.ext3 /dev/md0//格式化raid1.

mke2fs 1.39 (29-May-2006)

Filesystem label=

OS type: Linux

Block size=4096 (log=2)

Fragment size=4096 (log=2)

9781248 inodes, 19537664 blocks

976883 blocks (5.00%) reserved for the super user

First data block=0

Maximum filesystem blocks=0

597 block groups

32768 blocks per group, 32768 fragments per group

16384 inodes per group

Superblock backups stored on blocks:

32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,

4096000, 7962624, 11239424

Writing inode tables: done

Creating journal (32768 blocks): done

Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 21 mounts or

180 days, whichever comes first. Use tune2fs -c or -i to override.

9.[root@zh888 ~]# mount /dev/md0 /home/samba/software/ //挂载/dev/md0设备到/home/samba/software目录中。

[root@zh888 ~]# mount//查看挂载的目录。

/dev/hda3 on / type ext3 (rw)

proc on /proc type proc (rw)

sysfs on /sys type sysfs (rw)

devpts on /dev/pts type devpts (rw,gid=5,mode=620)

/dev/hda1 on /boot type ext3 (rw)

tmpfs on /dev/shm type tmpfs (rw)

none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)

sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)

/dev/md0 on /home/samba/software type ext3 (rw)//已经挂载上/dev/md0

10.[root@zh888 ~]# cat /proc/mdstat //查看mdstat状态。

Personalities : [raid1]

md0 : active raid1 hdd[1] hdb[0]

78150656 blocks [2/2] [UU]

[======>..............] resync = 30.0% (23462656/78150656) finish=31.6min speed=28792K/sec

unused devices: <none>//正在同步设备。

11.[root@zh888 ~]# mdadm --detail /dev/md0//查看状态可以是-D参数

/dev/md0:

Version : 0.90

Creation Time : Thu Sep 1 18:01:12 2011

Raid Level : raid1

Array Size : 740263618 (74.53 GiB 74.53 GB)

Raid Devices : 2

Total Devices : 2

Preferred Minor : 0

Persistence : Superblock is persistent

Update Time : Thu Sep 1 18:01:12 2011

State : clean

Active Devices : 2

Working Devices : 2

Failed Devices : 0

Spare Devices : 0

Chunk Size : 128K

UUID : a55d24d1:f8be2ab8:e606decc:41c96122

Events : 0.1

Number Major Minor RaidDevice State

0 3 64 0 active sync /dev/hdb

1 22 64 1 active sync /dev/hdd

11.创建LVM

lvm就是逻辑卷管理器

步骤分为：

1 创建pv(物理卷)

2 创建vg(卷组)

3 创建lv(逻辑卷)

好处,为文件系统提供一个透明的磁盘接口,利于扩容之类的。

12.[root@zh888 ~]# pvcreate /dev/md0//创建pv物理卷

Physical volume "/dev/md0" successfully created

13.[root@zh888 ~]# vgcreate datavg /dev/md0//常见datavg

Volume group "datavg" successfully created

14.[root@zh888 ~]# vgdisplay -v//显示datavg信息

Finding all volume groups

Finding volume group "datavg"

--- Volume group ---

VG Name datavg

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 74.53 GB

PE Size 4.00 MB

Total PE 19079

Alloc PE / Size 0 / 0

Free PE / Size 19079 / 74.53 GB

VG UUID IfweOP-2jnU-4VME-25Dp-Uy2x-Bbfn-IDbjvH

--- Physical volumes ---

PV Name /dev/md0

PV UUID 2kshX3-T60n-DWwV-DjTF-DxLI-mrzz-Z6He7k

PV Status allocatable

Total PE / Free PE 19079 / 19079

从上面显示的卷信息得知，datavg卷只有74.53 GB可用。

15.[root@zh888 ~]# lvcreate datavg --name=datalv --size=74G

Logical volume "datalv" created

16.[root@zh888 ~]# vgdisplay -v

Finding all volume groups

Finding volume group "datavg"

--- Volume group ---

VG Name datavg

System ID

Format lvm2

Metadata Areas 1

Metadata Sequence No 2

VG Access read/write

VG Status resizable

MAX LV 0

Cur LV 1

Open LV 0

Max PV 0

Cur PV 1

Act PV 1

VG Size 74.53 GB

PE Size 4.00 MB

Total PE 19079

Alloc PE / Size 18944 / 74.00 GB

Free PE / Size 135 / 540.00 MB

VG UUID IfweOP-2jnU-4VME-25Dp-Uy2x-Bbfn-IDbjvH

--- Logical volume ---

LV Name /dev/datavg/datalv

VG Name datavg

LV UUID Ndzr97-yxOn-HP4P-CNZg-1jpG-RaS2-4EBgkh

LV Write Access read/write

LV Status available

# open 0

LV Size 74.00 GB

Current LE 18944

Segments 1

Allocation inherit

Read ahead sectors auto

- currently set to 256

Block device 253:0

--- Physical volumes ---

PV Name /dev/md0

PV UUID 2kshX3-T60n-DWwV-DjTF-DxLI-mrzz-Z6He7k

PV Status allocatable

Total PE / Free PE 19079 / 135

17.[root@zh888 ~]# mkfs -t ext3 /dev/datavg/datalv//格式化datalv逻辑卷

mke2fs 1.39 (29-May-2006)

Filesystem label=

OS type: Linux

Block size=4096 (log=2)

Fragment size=4096 (log=2)

9699328 inodes, 19398656 blocks

969932 blocks (5.00%) reserved for the super user

First data block=0

Maximum filesystem blocks=0

592 block groups

32768 blocks per group, 32768 fragments per group

16384 inodes per group

Superblock backups stored on blocks:

32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,

4096000, 7962624, 11239424

Writing inode tables: done

Creating journal (32768 blocks): done

Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 22 mounts or

180 days, whichever comes first. Use tune2fs -c or -i to override.

18. [root@zh888 ~]# lvdisplay 查看lv逻辑卷然后 /dev/datavg/datalv /home/samba/software ext3 default 0 0 写入/etc/fstab中让系统开机启动挂载。

--- Logical volume ---

LV Name /dev/datavg/datalv

VG Name datavg

LV UUID Ndzr97-yxOn-HP4P-CNZg-1jpG-RaS2-4EBgkh

LV Write Access read/write

LV Status available

# open 0

LV Size 74.00 GB

Current LE 18944

Segments 1

Allocation inherit

Read ahead sectors auto

- currently set to 256

Block device 253:0

raid1和raid0测试速度。

19.[root@zh888 software]# dd if=/dev/zero of=file bs=1024k count=1k//测试raid0的速度

1024+0 records in

1024+0 records out

1073741824 bytes (1.1 GB) copied, 15.3735 seconds, 69.8 MB/s

写了1.1G的数据花费了15.3秒，

20.[root@zh888 software]# dd if=/dev/zero of=file bs=1024k count=1k//raid1的速度

1024+0 records in

1024+0 records out

1073741824 bytes (1.1 GB) copied, 29.8514 seconds, 36.0 MB/s

有一些特殊的设备文件。例如/dev/zero文件代表一个永远输出 0的设备文件，使用它作输入可以得到全为空的文件。因此可用来创建新文件和以覆盖的方式清除旧文件。下面使用dd命令将从zero设备中创建一个10K大小（bs决定每次读写1024字节，count定义读写次数为10次），但内容全为0的文件。

# dd if=/dev/zero of=file count=10 bs=1024

　　10+0 records in

　　10+0 records out

　　10240 bytes transferred in 0.001408 secs (7267903 b ytes/sec)

可以通过使用dd if=/dev/zero of=/file 来测试磁盘的纯写入性能

使用dd if=/file of=/dev/null 来测试磁盘的纯读取性能

使用dd if=/file1 of=/file2 来测试磁盘的读写性能

21.补充点mdadm的知识点

dadm有7中模式，下面列出了7种模式的命令格式，详细的选项，请参考man手册。

ASSEMBLE MODE :madam --assemble md-device options-and-component-devices

mdadm --assembel --scan md-devices-and-options

mdamd --assembel --scan options

BUILD MODE: mdadm --build device --chunk=X --level=Y --raid-devices=Z devices

CREATE MODE: mdadm --create device --chunk=X --level=Y --raid-devices=Z devices

MANAGE MODE: mdadm device options devices

MISC MODE: mdadm options ... devices ...

MONITOR MODE: mdadm --monitor options... devices...

GROW MODE:

1.查看

MISC模式

#mdadm --detail /dev/md0

#mdadm -D /dev/md0

2.停止

MISC模式

#mdadm -S /dev/md0

3.启动

ASSEMBLE模式

#mdadm -A /dev/md0 /dev/sd[bcd]1

启动指定的RAID，可以理解为将一个raid重新装配到系统中。

如果在前面已经配置了/etc/mdadm.conf文件，可以使用：

#mdadm -As /dev/md0

4.添加删除磁盘

mdadm可以在Manage模式下，对运行中的阵列进行添加及删除磁盘。常用于标识failed磁盘，增加spare（冗余）磁盘，以及替换磁盘等。

# mdadm /dev/md0 --fail /dev/sdd --remove /dev/sdd

# mdadm -D /dev/md0

# mdadm /dev/md0 --add /dev/sdd

# mdadm -D /dev/md0

--fail指定坏磁盘,--remove移走。

需要注意的是，对于某些RAID级别，如RAID0，是不能用--fail --remove --add的。

5.监控

MONITOR模式

# nohup mdadm --monitor --mail root --delay 200 /dev/md0 &

每200秒监控一次，当RAID出现错误时，发送邮件给root用户。

6.增加spare磁盘

可以通过在创建的时候指定冗余磁盘

#mdadm --create --verbose /dev/md0 --level=3 --raid-devices=3 -x1 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1

-x(--spare-devices=)参数指定冗余磁盘的数量。另外，对于full的阵列（例如已经有2个磁盘的RAID1），则直接使用-add参数，mdadm会自动把冗余的磁盘作为spare disk。

7.删除RAID

#mdadm -S /dev/md0

或

#rm /dev/md0

删除/etc/mdadm.conf文件；去除/etc/fstab文件中相关的行。

最后，用fdisk对磁盘进行重新分区。

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