• Linux软raid创建

      RAID: 

       HBA：基于主机的适配器 

       RAID：Redundent Array of Inexpensive Disks 廉价磁盘阵列

                                Independent       独立磁盘阵列

         Level：仅用于标识磁盘组合方式的不同，不能取代数据备份

            raid0，raid1，raid5，raid10，raid50，jbod

            raid0：提高读写性能，没有容错能力。至少需要两块磁盘 100%

            raid1：至少需要两块硬盘，镜像，硬件容错能力，读性能提升，写性能下降 50%

            raid4：至少需要三块硬盘，允许一块盘出错，读写性能提升，（n-1）/n

            raid5: 至少需要三块硬盘，允许一块盘出错，读写性能提升，（n-1）/n

            raid6: 至少需要四块磁盘，允许两块盘出错。读写性能提升，（n-2）/n

            raid10：至少需要四块磁盘。允许不同组内个各坏一块盘，读写性能提升，50%

            raid01：

            jbod：

          md，可以组合任何块设备

          mdadm，/etc/mdadm.conf

          mdadm:模式化的工具

            -A  Assemble 装配模式

            -C  Create 创建模式

              -n #：用于创建RAID设备的个数

              -x #: 热备磁盘的个数

              -l ：指定RAID级别

              -a ：=yes（自动为创建的RAID设备创建设备文件） md mdp part p 如何创建设备文件

              -c：指定块的大小，默认为512KB

            -F FOLLOW 监控

            -S 停止RAID

            -D --detail: 显示阵列详细信息

            Manage 管理模式专用项

              -f：模拟损害

              -r：模拟移除设备

              -a：模拟添加新设备

          watch 

            -n #:每个#执行一次指定的命令，单位为s

              [root@mail ~]# watch -n1 'cat /proc/mdstat'

       

      使用raid0创建一个6G大小的磁盘。

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        [root@mail ~]# fdisk /dev/sdc
        Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
        Building a new DOS disklabel with disk identifier 0xba68f31c.
        Changes will remain in memory only, until you decide to write them.
        After that, of course, the previous content won't be recoverable.
         
        Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
         
        WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
                 switch off the mode (command 'c') and change display units to
                 sectors (command 'u').
         
        Command (m for help): n
        Command action
           e   extended
           p   primary partition (1-4)
        p
        Partition number (1-4): 1
        First cylinder (1-2610, default 1):
        Using default value 1
        Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610): +6G
         
        Command (m for help): n
        Command action
           e   extended
           p   primary partition (1-4)
        p
        Partition number (1-4): 2
        First cylinder (785-2610, default 785):
        Using default value 785
        Last cylinder, +cylinders or +size{K,M,G} (785-2610, default 2610): +6G
         
        Command (m for help): t
        Partition number (1-4): 1
        Hex code (type L to list codes): fd
        Changed system type of partition 1 to fd (Linux raid autodetect)
         
        Command (m for help): t
        Partition number (1-4): 2
        Hex code (type L to list codes): fd
        Changed system type of partition 2 to fd (Linux raid autodetect)
         
        Command (m for help): w
        The partition table has been altered!
         
        Calling ioctl() to re-read partition table.
        Syncing disks.
        [root@mail ~]# mdadm -C /dev/md0 -a yes -l 0 -n 2 /dev/sdc{1,2}
        mdadm: Defaulting to version 1.2 metadata
        mdadm: array /dev/md0 started.
        [root@mail ~]# cat /proc/mdstat
        Personalities : [raid0]
        md0 : active raid0 sdc2[1] sdc1[0]
              12585984 blocks super 1.2 512k chunks
               
        unused devices: <none>
        [root@mail ~]# mdadm -D /dev/md0
        /dev/md0:
                Version : 1.2
          Creation Time : Tue May 10 20:19:43 2016
             Raid Level : raid0
             Array Size : 12585984 (12.00 GiB 12.89 GB)
           Raid Devices : 2
          Total Devices : 2
            Persistence : Superblock is persistent
         
            Update Time : Tue May 10 20:19:43 2016
                  State : clean
         Active Devices : 2
        Working Devices : 2
         Failed Devices : 0
          Spare Devices : 0
         
             Chunk Size : 512K
         
                   Name : mail.saviorsyang.com:0  (local to host mail.saviorsyang.com)
                   UUID : b5ec8803:366d2e9d:a1ddd0f2:58101d5c
                 Events : 0
         
            Number   Major   Minor   RaidDevice State
               0       8       33        0      active sync   /dev/sdc1
               1       8       34        1      active sync   /dev/sdc2
         
        [root@mail ~]# mke2fs -t ext4 /dev/md0
        mke2fs 1.43-WIP (20-Jun-2013)
        Filesystem label=
        OS type: Linux
        Block size=4096 (log=2)
        Fragment size=4096 (log=2)
        Stride=128 blocks, Stripe width=256 blocks
        786864 inodes, 3146496 blocks
        157324 blocks (5.00%) reserved for the super user
        First data block=0
        Maximum filesystem blocks=3225419776
        97 block groups
        32768 blocks per group, 32768 fragments per group
        8112 inodes per group
        Superblock backups stored on blocks:
          32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208
         
        Allocating group tables: done                           
        Writing inode tables: done                           
        Creating journal (32768 blocks):
        done
        Writing superblocks and filesystem accounting information: done
         
        [root@mail ~]# mkdir  /test/md0
        [root@mail ~]# mount /dev/md0 /test/md0
        [root@mail ~]# mount
        /dev/mapper/vg_demo-lv_root on / type ext4 (rw)
        proc on /proc type proc (rw)
        sysfs on /sys type sysfs (rw)
        devpts on /dev/pts type devpts (rw,gid=5,mode=620)
        tmpfs on /dev/shm type tmpfs (rw)
        /dev/sda1 on /boot type ext4 (rw)
        /dev/sdb1 on /student type ext4 (rw)
        /dev/sr0 on /mnt type iso9660 (ro)
        none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
        /dev/md0 on /test/md0 type ext4 (rw)

        使用raid1创建一个2G大小的磁盘。

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        [root@mail ~]# fdisk /dev/sdc
         
        WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
                 switch off the mode (command 'c') and change display units to
                 sectors (command 'u').
         
        Command (m for help): n
        Command action
           e   extended
           p   primary partition (1-4)
        e
        Partition number (1-4):
        Value out of range.
        Partition number (1-4): 3
        First cylinder (1569-2610, default 1569):
        Using default value 1569
        Last cylinder, +cylinders or +size{K,M,G} (1569-2610, default 2610):
        Using default value 2610
         
        Command (m for help): n
        Command action
           l   logical (5 or over)
           p   primary partition (1-4)
        l
        First cylinder (1569-2610, default 1569):
        Using default value 1569
        Last cylinder, +cylinders or +size{K,M,G} (1569-2610, default 2610): +2G
         
        Command (m for help): n
        Command action
           l   logical (5 or over)
           p   primary partition (1-4)
        l
        First cylinder (1831-2610, default 1831):
        Using default value 1831
        Last cylinder, +cylinders or +size{K,M,G} (1831-2610, default 2610): +2G
         
        Command (m for help): w
        The partition table has been altered!
         
        Calling ioctl() to re-read partition table.
         
        WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
        The kernel still uses the old table. The new table will be used at
        the next reboot or after you run partprobe(8) or kpartx(8)
        Syncing disks.
         
        [root@mail ~]# fdisk /dev/sdc
         
        WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
                 switch off the mode (command 'c') and change display units to
                 sectors (command 'u').
         
        Command (m for help): t
        Partition number (1-6): 5
        Hex code (type L to list codes): fd
        Changed system type of partition 5 to fd (Linux raid autodetect)
         
        Command (m for help): t
        Partition number (1-6): 6
        Hex code (type L to list codes): fd
        Changed system type of partition 6 to fd (Linux raid autodetect)
         
        Command (m for help): w
        The partition table has been altered!
         
        Calling ioctl() to re-read partition table.
         
        WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
        The kernel still uses the old table. The new table will be used at
        the next reboot or after you run partprobe(8) or kpartx(8)
        Syncing disks.
             
        [root@mail ~]# partx /dev/sdc
        # 1:        63- 12594959 ( 12594897 sectors,   6448 MB)
        # 2:  12594960- 25189919 ( 12594960 sectors,   6448 MB)
        # 3:  25189920- 41929649 ( 16739730 sectors,   8570 MB)
        # 4:         0-       -1 (        0 sectors,      0 MB)
        # 5:  25189983- 29398949 (  4208967 sectors,   2154 MB)
        # 6:  29399013- 33607979 (  4208967 sectors,   2154 MB)
         
        [root@mail ~]# cat /proc/partitions
        major minor  #blocks  name
         
           8       32   20971520 sdc
           8       33    6297448 sdc1
           8       34    6297480 sdc2
           8       35         31 sdc3
           8       37    2104483 sdc5
           8       38    2104483 sdc6
           8        0   52428800 sda
           8        1     512000 sda1
           8        2   51915776 sda2
           8       16  524288000 sdb
           8       17  524281243 sdb1
           8       48   20971520 sdd
          11        0    3763200 sr0
         252        0   47816704 dm-0
         252        1    4096000 dm-1
           9        0   12585984 md0
        [root@mail ~]# mdadm -C /dev/md1 -a yes -l 1 -n 2 /dev/sdc{5,6}
        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=0.90
        Continue creating array? yes
        mdadm: Defaulting to version 1.2 metadata
        mdadm: array /dev/md1 started.
        [root@mail ~]# cat /proc/mdstat
        Personalities : [raid0] [raid1]
        md1 : active raid1 sdc6[1] sdc5[0]
              2102400 blocks super 1.2 [2/2] [UU]
              [=================>...]  resync = 85.5% (1800064/2102400) finish=0.0min speed=200007K/sec
               
        md0 : active raid0 sdc2[1] sdc1[0]
              12585984 blocks super 1.2 512k chunks
               
        unused devices: <none>
        [root@mail ~]# cat /proc/mdstat
        Personalities : [raid0] [raid1]
        md1 : active raid1 sdc6[1] sdc5[0]
              2102400 blocks super 1.2 [2/2] [UU]
               
        md0 : active raid0 sdc2[1] sdc1[0]
              12585984 blocks super 1.2 512k chunks
               
        unused devices: <none>
         
         
        [root@mail ~]#
        [root@mail ~]# mke2fs -t ext4 /dev/md1
        mke2fs 1.43-WIP (20-Jun-2013)
        Filesystem label=
        OS type: Linux
        Block size=4096 (log=2)
        Fragment size=4096 (log=2)
        Stride=0 blocks, Stripe width=0 blocks
        131648 inodes, 525600 blocks
        26280 blocks (5.00%) reserved for the super user
        First data block=0
        Maximum filesystem blocks=541065216
        17 block groups
        32768 blocks per group, 32768 fragments per group
        7744 inodes per group
        Superblock backups stored on blocks:
            32768, 98304, 163840, 229376, 294912
         
        Allocating group tables: done                           
        Writing inode tables: done                           
        Creating journal (16384 blocks): done
        Writing superblocks and filesystem accounting information: done
         
        [root@mail ~]# mkdir -pv /test/md1
        [root@mail ~]# mount /dev/md1 /test/md1
        [root@mail ~]# mount
        /dev/mapper/vg_demo-lv_root on / type ext4 (rw)
        proc on /proc type proc (rw)
        sysfs on /sys type sysfs (rw)
        devpts on /dev/pts type devpts (rw,gid=5,mode=620)
        tmpfs on /dev/shm type tmpfs (rw)
        /dev/sda1 on /boot type ext4 (rw)
        /dev/sdb1 on /student type ext4 (rw)
        /dev/sr0 on /mnt type iso9660 (ro)
        none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
        /dev/md1 on /test/md1 type ext4 (rw)
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    2. 原文地址：https://www.cnblogs.com/Saviorsyang/p/5738394.html
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