RAID(Reduntant Arrays of Independent Disks),即独立冗余磁盘阵列。
RAID的级别：
Raid 0: 条带
Raid 1: 镜像
Raid 2,3,4,5 等校验码类型
Raid 01, Raid 10, Raid 50 等等。
以下是模拟创建RAID1 （2G）的过程：
1、创建raid auto分区(fd)
[root@ant-colonies ~]# fdisk /dev/sda
...Command (m for help): t
Partition number (1-9): 8Hex code (type L to list codes): fdChanged system type of partition 8 to fd (Linux raid autodetect).../dev/sda8 3424 3685 2104483+ fd Linux raid autodetect
/dev/sda9 3686 3947 2104483+ fd Linux raid autodetect/dev/sda10 3948 4209 2104483+ fd Linux raid autodetect[root@ant-colonies ~]# partprobe #通知内核重新读取分区信息
[root@ant-colonies ~]# cat /proc/partitions
major minor #blocks name 8 0 125829120 sda... 8 8 2104483 sda8 8 9 2104483 sda9 8 10 2104483 sda10
2、将磁盘分区做成RAID盘
[root@ant-colonies ~]# mdadm -C /dev/md0 -a yes -l 1 -n 2 /dev/sda{8,9}
mdadm: Note: this array has metadata at the start 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=0.90Continue creating array? ymdadm: Defaulting to version 1.2 metadatamdadm: array /dev/md0 started.[root@ant-colonies ~]# fdisk -l
...
Disk /dev/md0: 2152 MB, 2152857600 bytes
2 heads, 4 sectors/track, 525600 cylindersUnits = cylinders of 8 * 512 = 4096 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x00000000[root@ant-colonies ~]# cat /proc/mdstat # 查看RAID信息配置文件
Personalities : [raid1] md0 : active raid1 sda9[1] sda8[0] 2102400 blocks super 1.2 [2/2] [UU] unused devices: <none>[root@ant-colonies ~]# mdadm -D /dev/md0 # 查看RAID的详细信息
/dev/md0: Version : 1.2 Creation Time : Fri Jan 20 05:29:57 2017 Raid Level : raid1 Array Size : 2102400 (2.01 GiB 2.15 GB) Used Dev Size : 2102400 (2.01 GiB 2.15 GB) Raid Devices : 2 Total Devices : 2 Persistence : Superblock is persistent Update Time : Fri Jan 20 05:30:08 2017 State : clean Active Devices : 2Working Devices : 2 Failed Devices : 0 Spare Devices : 0 Name : ant-colonies:0 (local to host ant-colonies) UUID : xxxxxxxxxxxxxxxx Events : 17 Number Major Minor RaidDevice State 0 8 8 0 active sync /dev/sda8 1 8 9 1 active sync /dev/sda9
3、格式化RAID
[root@ant-colonies ~]# mke2fs -j -E stride=16 /dev/md0
mke2fs 1.41.12 (17-May-2010)Filesystem label=OS type: LinuxBlock size=4096 (log=2)Fragment size=4096 (log=2)Stride=16 blocks, Stripe width=0 blocks131648 inodes, 525600 blocks26280 blocks (5.00%) reserved for the super userFirst data block=0Maximum filesystem blocks=54106521617 block groups32768 blocks per group, 32768 fragments per group7744 inodes per groupSuperblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912Writing inode tables: done Creating journal (16384 blocks): doneWriting superblocks and filesystem accounting information: doneThis filesystem will be automatically checked every 30 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override.
4、模拟磁盘损坏
[root@ant-colonies ~]# mdadm /dev/md0 -f /dev/sda8
mdadm: set /dev/sda8 faulty in /dev/md0[root@ant-colonies ~]# cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sda9[1] sda8[0](F) 2102400 blocks super 1.2 [2/1] [_U] unused devices: <none>[root@ant-colonies ~]# mdadm --detail /dev/md0/dev/md0: Version : 1.2 Creation Time : Fri Jan 20 05:29:57 2017 Raid Level : raid1 Array Size : 2102400 (2.01 GiB 2.15 GB) Used Dev Size : 2102400 (2.01 GiB 2.15 GB) Raid Devices : 2 Total Devices : 2 Persistence : Superblock is persistent Update Time : Fri Jan 20 05:55:52 2017 State : clean, degraded Active Devices : 1Working Devices : 1 Failed Devices : 1 Spare Devices : 0 Name : ant-colonies:0 (local to host ant-colonies) UUID : xxxxxxxxxxxxxxxx Events : 19 Number Major Minor RaidDevice State 0 0 0 0 removed 1 8 9 1 active sync /dev/sda9 0 8 8 - faulty /dev/sda85、移除损坏盘[root@ant-colonies ~]# mdadm /dev/md0 -r /dev/sda8
mdadm: hot removed /dev/sda8 from /dev/md0[root@ant-colonies ~]# mdadm -D /dev/md0/dev/md0: Version : 1.2 Creation Time : Fri Jan 20 05:29:57 2017 Raid Level : raid1 Array Size : 2102400 (2.01 GiB 2.15 GB) Used Dev Size : 2102400 (2.01 GiB 2.15 GB) Raid Devices : 2 Total Devices : 1 Persistence : Superblock is persistent Update Time : Fri Jan 20 06:02:20 2017 State : clean, degraded Active Devices : 1Working Devices : 1 Failed Devices : 0 Spare Devices : 0 Name : ant-colonies:0 (local to host ant-colonies) UUID : 7e24b602:766c7d33:85e03d1a:868c3d08 Events : 20 Number Major Minor RaidDevice State 0 0 0 0 removed 1 8 9 1 active sync /dev/sda9[root@ant-colonies ~]# cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sda9[1] 2102400 blocks super 1.2 [2/1] [_U] unused devices: <none>6、添加新盘到阵列[root@ant-colonies ~]# mdadm /dev/md0 -a /dev/sda10 # 不需要重新格式化mdadm: added /dev/sda10[root@ant-colonies ~]# cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sda10[2] sda9[1] 2102400 blocks super 1.2 [2/2] [UU] unused devices: <none>7、增加热备盘[root@ant-colonies ~]# mdadm /dev/md0 -a /dev/sda8
mdadm: added /dev/sda8[root@ant-colonies ~]# cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sda8[3](S) sda10[2] sda9[1] 2102400 blocks super 1.2 [2/2] [UU] unused devices: <none>[root@ant-colonies ~]# mdadm -D /dev/md0/dev/md0: Version : 1.2 Creation Time : Fri Jan 20 05:29:57 2017 Raid Level : raid1 Array Size : 2102400 (2.01 GiB 2.15 GB) Used Dev Size : 2102400 (2.01 GiB 2.15 GB) Raid Devices : 2 Total Devices : 3 Persistence : Superblock is persistent Update Time : Fri Jan 20 06:11:46 2017 State : clean Active Devices : 2Working Devices : 3 Failed Devices : 0 Spare Devices : 1 Name : ant-colonies:0 (local to host ant-colonies) UUID : xxxxxxxxxxxxxxxx Events : 40 Number Major Minor RaidDevice State 2 8 10 0 active sync /dev/sda10 1 8 9 1 active sync /dev/sda9 3 8 8 - spare /dev/sda88、停止RAID阵列[root@ant-colonies ~]# mdadm -S /dev/md0
mdadm: stopped /dev/md0[root@ant-colonies ~]# cat /proc/mdstat Personalities : [raid1] unused devices: <none>[root@ant-colonies ~]# mdadm -D /dev/md0mdadm: cannot open /dev/md0: No such file or directory9、重新启动RAID阵列[root@ant-colonies ~]# mdadm -A /dev/md0 /dev/sda{9,10,8}
mdadm: /dev/md0 has been started with 2 drives and 1 spare.[root@ant-colonies ~]# mdadm -D --scan # 查看磁盘阵列的磁盘数据信息
ARRAY /dev/md0 metadata=1.2 name=ant-colonies:0 UID=7e24b602:766c7d33:85e03d1a:868c3d08[root@ant-colonies ~]# mdadm -D --scan > /etc/mdadm.conf # 将磁盘阵列信息添加到系统配置文件，当阵列重新装配时系统会自动挂载对应的磁盘[root@ant-colonies ~]# mdadm --stop /dev/md0mdadm: stopped /dev/md0[root@ant-colonies ~]# mdadm -A /dev/md0mdadm: /dev/md0 has been started with 2 drives.
10、模拟RAID阵列一块盘损坏，热备盘自动启用作为镜像
[root@ant-colonies ~]# mdadm /dev/md0 --fail /dev/sda10
mdadm: set /dev/sda10 faulty in /dev/md0[root@ant-colonies ~]# cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sda10[2](F) sda8[3] sda9[1] 2102400 blocks super 1.2 [2/1] [_U] [===============>.....] recovery = 76.0% (1600000/2102400) finish=0.0min speed=228571K/sec # 显示系统在恢复数据至sda8 unused devices: <none>[root@ant-colonies ~]# cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sda10[2](F) sda8[3] sda9[1] 2102400 blocks super 1.2 [2/2] [UU] unused devices: <none>[root@ant-colonies ~]# watch -n 2 `cat /proc/mdstat` # watch每2s执行一次cat，动态查看数据恢复情况附：
mdadm: 将任何块设备做成RAID
模式化的命令： 创建模式 -C 专用选项： -l: 级别 -n #: 设备个数 -a {yes|no}: 是否自动为其创建设备文件 -c: CHUNK大小, 2^n，默认为64K -x #: 指定空闲盘个数 管理模式 --add, --remove, --fail mdadm /dev/md# --fail /dev/sda7 监控模式 -F 增长模式 -G 装配模式 -A查看RAID阵列的详细信息mdadm -D /dev/md# --detail 停止阵列： mdadm -S /dev/md# --stop
watch: 周期性地执行指定命令，并以全屏方式显示结果
-n #：指定周期长度，单位为秒，默认为2格式： watch -n # 'COMMAND' 将当前RAID信息保存至配置文件，以便以后进行装配：mdamd -D --scan > /etc/mdadm.confmke2fs -j -E stride=16 /dev/md2 // stride=chuncks/blocksizes (指定stride即条带大小)