服务器评测
一 什么是RAID10
RAID 10/01细分为RAID 1+0或RAID 0+1。
RAID 1+0是先镜射再分割资料，再将所有硬碟分为两组，视为是RAID 0的最低组合，然后将这两组各自视为RAID 1运作。
RAID 0+1则是跟RAID 1+0的程序相反，是先分割再将资料镜射到两组硬碟。它将所有的硬碟分为两组，变成RAID 1的最低组合，而将两组硬碟各自视为RAID 0运作。
效能上，RAID 0+1比RAID 1+0有着更快的读写速度。
可靠性上，当RAID 1+0有一个硬碟受损，其余三个硬碟会继续运作。RAID 0+1 只要有一个硬碟受损，同组RAID 0的另一只硬碟亦会停止运作，只剩下两个硬碟运作，可靠性较低。
因此，RAID 10远较RAID 01常用，零售主机板绝大部份支援RAID 0/1/5/10，但不支援RAID 01。
推荐阅读：
Debian软RAID安装笔记 – 使用mdadm安装RAID1 http://www.linuxidc.com/Linux/2013-06/86487.htm
RAID技术穷途末路了吗？ http://www.linuxidc.com/Linux/2013-06/86158.htm
常用RAID技术介绍以及示例演示(多图) http://www.linuxidc.com/Linux/2013-03/81481.htm
Linux实现最常用的磁盘阵列– RAID5 http://www.linuxidc.com/Linux/2013-01/77880.htm
RAID0+1和RAID5的性能测试结果 http://www.linuxidc.com/Linux/2012-07/65567.htm
二 RAID10演示
第一步 对磁盘进行分区
#分别对sdb sdc sde sde分区
[root@serv01 ~]# fdisk /dev/sdb
[root@serv01 ~]# fdisk /dev/sdc
[root@serv01 ~]# fdisk /dev/sdd
[root@serv01 ~]# fdisk /dev/sde
[root@serv01 ~]# ls /dev/sd
sda sda1 sda2 sda3 sda4 sda5 sdb sdb1 sdc sdc1 sdd sdd1 sde sde1 sdf sdg
[root@serv01 ~]# mdadm -C /dev/md0 -l 1 -n2 /dev/md0 /dev/md1
mdadm: device /dev/md0 not suitable for anystyle of array
第二步 创建RAID10
#创建/dev/md0，RAID1
[root@serv01 ~]# mdadm -C /dev/md0 -l 1 -n2 /dev/sdb1 /dev/sdc1
mdadm: Note: this array has metadata at thestart and
may not be suitable as a boot device. If you plan to
store ‘/boot’ on this device please ensure that
your boot-loader understands md/v1.x metadata, or use
–metadata=0.90
Continue creating array? y
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.
#创建/dev/md1，RAID1
[root@serv01 ~]# mdadm -C /dev/md1 -l 1 -n2 /dev/sdd1 /dev/sde1
mdadm: Note: this array has metadata at thestart and
may not be suitable as a boot device. If you plan to
store ‘/boot’ on this device please ensure that
your boot-loader understands md/v1.x metadata, or use
–metadata=0.90
Continue creating array? y
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md1 started.
#创建/dev/md10，RAID0
[root@serv01 ~]# mdadm -C /dev/md10 -l 0 -n2 /dev/md0 /dev/md1
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md10 started.
[root@serv01 ~]# cat /proc/mdstat
Personalities : [raid1] [raid0]
md10 : active raid0 md1[1] md0[0]
4188160 blocks super 1.2 512k chunks
md1 : active raid1 sde1[1] sdd1[0]
2095415 blocks super 1.2 [2/2] [UU]
md0 : active raid1 sdc1[1] sdb1[0]
2095415 blocks super 1.2 [2/2] [UU]
unused devices: <none>
[root@serv01 ~]# mkfs.ext4 /dev/md10
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=128 blocks, Stripe width=256 blocks
262144 inodes, 1047040 blocks
52352 blocks (5.00%) reserved for the superuser
First data block=0
Maximum filesystem blocks=1073741824
32 block groups
32768 blocks per group, 32768 fragments pergroup
8192 inodes per group
Superblock backups stored on blocks:
32768,98304, 163840, 229376, 294912, 819200, 884736
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystemaccounting information: done
This filesystem will be automaticallychecked every 39 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@serv01 ~]# mkdir /web
[root@serv01 ~]# mount /dev/md10 /web
[root@serv01 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 9.7G 1.1G 8.1G 12% /
tmpfs 385M 0 385M 0% /dev/shm
/dev/sda1 194M 25M 160M 14% /boot
/dev/sda5 4.0G 137M 3.7G 4% /opt
/dev/sr0 3.4G 3.4G 0 100% /iso
/dev/md10 4.0G 72M 3.7G 2% /web
[root@serv01 ~]# mdadm –detail –scan
ARRAY /dev/md0 metadata=1.2name=serv01.host.com:0 UUID=78656148:8251f76a:a758c84e:f8927ae0
ARRAY /dev/md1 metadata=1.2name=serv01.host.com:1 UUID=176f932e:a6451cd4:860a9cf7:847b51b7
ARRAY /dev/md10 metadata=1.2name=serv01.host.com:10 UUID=0428d240:4e9d097a:80bfe439:2802ff3e
[root@serv01 ~]# mdadm –detail –scan >/etc/mdadm.conf
[root@serv01 ~]# vim /etc/fstab
[root@serv01 ~]# echo “/dev/md10 /webext4 defaults 1 2” >> /etc/fstab
第三步 重启后发现系统坏掉，很显然RAID10不能正常使用
[root@serv01 ~]# reboot
#重启后系统不能正常启动，把添加到fstab中的关于RAID10的那一行删除
#硬RAID才可以实现这个功能，软RAID只能做演示
#注意：默认跟分区是以只读的形式挂载，需要重新挂载
[root@serv01 ~]# mount -o remount,rw /
第四步 固定名字，也不能正常使用
[root@serv01 ~]# mdadm –assemble /dev/md10/dev/md0 /dev/md1
mdadm: no correct container type: /dev/md0
mdadm: /dev/md0 has no superblock -assembly aborted
[root@serv01 ~]# mdadm –assemble /dev/md0/dev/sdb1 /dev/sdc1
mdadm: cannot open device /dev/sdb1: Deviceor resource busy
mdadm: /dev/sdb1 has no superblock -assembly aborted
[root@serv01 ~]# mdadm –assemble /dev/md0/dev/sdc1 /dev/sdc1
[root@serv01 ~]# mdadm –manage /dev/md0–stop
mdadm: stopped /dev/md0
[root@serv01 ~]# mdadm –manage /dev/md1–stop
mdadm: stopped /dev/md1
[root@serv01 ~]# mdadm –assemble /dev/md0/dev/sdb1 /dev/sdc1
mdadm: /dev/md0 has been started with 2drives.
[root@serv01 ~]# mdadm –assemble /dev/md1/dev/sdd1 /dev/sde1
mdadm: /dev/md1 has been started with 2drives.
[root@serv01 ~]# mdadm –assemble /dev/md10/dev/md0 /dev/md1
mdadm: /dev/md10 has been started with 2drives.
[root@serv01 ~]# cat /proc/mdstat
Personalities : [raid1] [raid0]
md10 : active raid0 md0[0] md1[1]
4188160 blocks super 1.2 512k chunks
md1 : active raid1 sdd1[0] sde1[1]
2095415 blocks super 1.2 [2/2] [UU]
md0 : active raid1 sdb1[0] sdc1[1]
2095415 blocks super 1.2 [2/2] [UU]
unused devices: <none>
第五步 实验完毕，停掉硬盘，清空磁盘
[root@serv01 ~]# mdadm –manage /dev/md0–stop
mdadm: Cannot get exclusive access to/dev/md0:Perhaps a running process, mounted filesystem or active volume group?
[root@serv01 ~]# mdadm –manage /dev/md10–stop
mdadm: stopped /dev/md10
[root@serv01 ~]# mdadm –manage /dev/md0–stop
mdadm: stopped /dev/md0
[root@serv01 ~]# mdadm –manage /dev/md1–stop
mdadm: stopped /dev/md1
[root@serv01 ~]# mdadm –misc –zero-superblock/dev/sdb1
[root@serv01 ~]# mdadm –misc–zero-superblock /dev/sdc1
[root@serv01 ~]# mdadm –misc–zero-superblock /dev/sdd1
[root@serv01 ~]# mdadm –misc–zero-superblock /dev/sde1
[root@serv01 ~]# mdadm -E /dev/sdb1
mdadm: No md superblock detected on/dev/sdb1.
[root@serv01 ~]# mdadm -E /dev/sdd1
mdadm: No md superblock detected on/dev/sdd1.
[root@serv01 ~]# mdadm -E /dev/sdc1
mdadm: No md superblock detected on/dev/sdc1.
[root@serv01 ~]# mdadm -E /dev/sde1
mdadm: No md superblock detected on/dev/sde1.
三 相关文章
磁盘管理——RAID 0 http://www.linuxidc.com/Linux/2013-08/88577.htm
磁盘管理——RAID 1 http://www.linuxidc.com/Linux/2013-08/88616.htm
磁盘管理——RAID 5 http://www.linuxidc.com/Linux/2013-08/89040.htm
