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note_9.3_RAID以及watch

note_9.3_RAID以及watch

作者: 人間失格_430b | 来源:发表于2019-02-17 22:04 被阅读0次

RAID:

Redundant Arrays of Inexpensive(Independence) Disks

Berkeley: A case for Redundent Arrays of Inexpensive Disks RAID

提高IO能力：
  磁盘并行读写
提高耐用性：
  磁盘冗余来实现

级别：多块磁盘组织在一起的工作方式有所不同；
  RAID实现的方式：
    外接式磁盘阵列：通过扩展卡提供适配能力
    内接式RAID：主板集成RAID控制器
    Software RAID：

级别：level

  • RAID-0：0, 条带卷，strip;
  • RAID-1: 1, 镜像卷，mirror;
  • RAID-2
    ..
  • RAID-5：1块校验盘
  • RAID-6：2块校验盘
  • RAID10
  • RAID01

  • RAID-0:
    读、写性能提升；
    可用空间：N*min(S1,S2,...)
    无容错能力
    最少磁盘数：2, 2+

  • RAID-1：
    读性能提升、写性能略有下降；
    可用空间：1*min(S1,S2,...)
    有冗余能力（数据备份）
    最少磁盘数：2, 2+

  • RAID-4：
    至少3个盘，一个盘作检验盘

  • RAID-5：
    读、写性能提升
    可用空间：(N-1)*min(S1,S2,...)
    有容错能力：1块磁盘
    最少磁盘数：3, 3+
    循环存放校验数据

  • RAID-6：
    读、写性能提升
    可用空间：(N-2)*min(S1,S2,...)
    有容错能力：2块磁盘
    最少磁盘数：4, 4+

混合类型

  • RAID-10：
    读、写性能提升
    可用空间：N*min(S1,S2,...)/2
    有容错能力：每组镜像最多只能坏一块；
    最少磁盘数：4, 4+

  • RAID-01:

  • RAID-50、RAID7

JBOD：Just a Bunch Of Disks

功能：将多块磁盘的空间合并一个大的连续空间使用；
  可用空间：sum(S1,S2,...)

常用级别：RAID-0, RAID-1, RAID-5, RAID-10, RAID-50, JBOD

实现方式：

  硬件实现方式
  软件实现方式

CentOS 6上的软件RAID的实现：
  结合内核中的md(multi devices)

mdadm：模式化的工具

命令的语法格式：
  mdadm [mode] <raiddevice> [options] <component-devices>
支持的RAID级别：LINEAR, RAID0, RAID1, RAID4, RAID5, RAID6, RAID10;

模式：
  创建：-C
  装配: -A
  监控: -F
  管理：-f, -r, -a

<raiddevice>: /dev/md#
<component-devices>: 任意块设备

                    -C: 创建模式
                        -n #: 使用#个块设备来创建此RAID；
                        -l #：指明要创建的RAID的级别；
                        -a {yes|no}：自动创建目标RAID设备的设备文件；
                        -c CHUNK_SIZE:A suffix of 'K', 'M' or 'G' can be given
                        -x #: 指明空闲盘的个数；

                        例如：创建一个10G可用空间的RAID5；

                    -D：显示raid的详细信息；
                        mdadm -D /dev/md#

                    管理模式：
                        -f: 标记指定磁盘为损坏；
                        -a: 添加磁盘
                        -r: 移除磁盘

  • 观察md的状态：
      cat /proc/mdstat

  • 停止md设备：
      mdadm -S /dev/md#

watch命令：

  -n #: 刷新间隔，单位是秒

  watch -n# 'COMMAND'

报错

[root@localhost ~]# blkid
/dev/sdb5: LABEL="backup" UUID="5176d653-a095-4f5e-8646-2d0e26fc3315" TYPE="ext4" 
/dev/sdb6: LABEL="backup" UUID="1304b977-620e-41fc-9d7c-5b58d8b8500b" TYPE="ext4" 
/dev/sdb7: LABEL="backup" UUID="7e70c845-41f4-4330-b85d-18e4e2a36a24" TYPE="ext4" 
/dev/sdb8: LABEL="backup" UUID="beeb1218-e4bc-4d6d-ae5d-592a47a6f086" TYPE="ext4" 
/dev/sda1: UUID="6e0c483a-767f-4836-9722-4ee11ad0e354" TYPE="xfs" 
/dev/sda2: UUID="5l05VF-4oRE-Nbpz-YnuF-76il-fjGc-EfTwst" TYPE="LVM2_member" 
/dev/sr0: UUID="2018-11-25-23-54-16-00" LABEL="CentOS 7 x86_64" TYPE="iso9660" PTTYPE="dos" 
/dev/mapper/centos-root: UUID="bd000f98-9676-4f6d-810c-9c52a4f8f20c" TYPE="xfs" 
/dev/mapper/centos-swap: UUID="383176d7-ce29-4055-bfdc-93832f4610e8" TYPE="swap" 
/dev/mapper/centos-home: UUID="f061c27e-d48b-491f-bdf3-28545428d3b5" TYPE="xfs" 
[root@localhost ~]# mke2fs -t ext3 /dev/sdb{5,6,7,8}
mke2fs 1.42.9 (28-Dec-2013)
mke2fs: invalid blocks '/dev/sdb6' on device '/dev/sdb5'

[root@localhost ~]# mdadm -C -n 3 -l 1 -a yes -c 128K -x 1 /dev/sdb{5,6,7}
mdadm: device /dev/sdb5 exists but is not an md array.
[root@localhost ~]# mdadm -C /dev/md0 -n 3 -l 1 -a yes -c 128K -x 1 /dev/sdb{5,6,7}
mdadm: You haven't given enough devices (real or missing) to create this array

练习

1.创建一个可用空间为5G的RAID1设备，要求其chunk大小为128k，文件系统为ext4，有一个空闲盘，开机可自动挂载至/backup目录；
2.创建一个可用空间为10G的RAID10设备，要求其chunk大小为256k，文件系统为ext4，开机可自动挂载至/mydata目录；

A1

创建4个5G的分区并标为RAID并重读分区表

[root@localhost ~]# fdisk /dev/sdb
Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.


Command (m for help): n
Partition type:
   p   primary (0 primary, 0 extended, 4 free)
   e   extended
Select (default p): e
Partition number (1-4, default 1): 
First sector (2048-41943039, default 2048): 
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): 
Using default value 41943039
Partition 1 of type Extended and of size 20 GiB is set

Command (m for help): n
Partition type:
   p   primary (0 primary, 1 extended, 3 free)
   l   logical (numbered from 5)
Select (default p): l
Adding logical partition 5
First sector (4096-41943039, default 4096): 
Using default value 4096
Last sector, +sectors or +size{K,M,G} (4096-41943039, default 41943039): +5G
Partition 5 of type Linux and of size 5 GiB is set

Command (m for help): n
Partition type:
   p   primary (0 primary, 1 extended, 3 free)
   l   logical (numbered from 5)
Select (default p): l
Adding logical partition 6
First sector (10491904-41943039, default 10491904): 
Using default value 10491904
Last sector, +sectors or +size{K,M,G} (10491904-41943039, default 41943039): +5G
Partition 6 of type Linux and of size 5 GiB is set

Command (m for help): n
Partition type:
   p   primary (0 primary, 1 extended, 3 free)
   l   logical (numbered from 5)
Select (default p): l 
Adding logical partition 7
First sector (20979712-41943039, default 20979712): 
Using default value 20979712
Last sector, +sectors or +size{K,M,G} (20979712-41943039, default 41943039): +5G
Partition 7 of type Linux and of size 5 GiB is set

Command (m for help): n
Partition type:
   p   primary (0 primary, 1 extended, 3 free)
   l   logical (numbered from 5)
Select (default p): l
Adding logical partition 8
First sector (31467520-41943039, default 31467520): 
Using default value 31467520
Last sector, +sectors or +size{K,M,G} (31467520-41943039, default 41943039): 
Using default value 41943039
Partition 8 of type Linux and of size 5 GiB is set

Command (m for help): t
Partition number (1,5-8, default 8): 5
Hex code (type L to list all codes): fd
Changed type of partition 'VMware VMFS' to 'Linux raid autodetect'

Command (m for help): t
Partition number (1,5-8, default 8): 6
Hex code (type L to list all codes): fd
Changed type of partition 'Linux' to 'Linux raid autodetect'

Command (m for help): t
Partition number (1,5-8, default 8): 7
Hex code (type L to list all codes): fd
Changed type of partition 'Linux' to 'Linux raid autodetect'

Command (m for help): t
Partition number (1,5-8, default 8): 
Hex code (type L to list all codes): fd
Changed type of partition 'Linux' to 'Linux raid autodetect'

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
[root@localhost ~]# fdisk -l /dev/sdb

Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x13ceef16

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048    41943039    20970496    5  Extended
/dev/sdb5            4096    10489855     5242880   fd  Linux raid autodetect
/dev/sdb6        10491904    20977663     5242880   fd  Linux raid autodetect
/dev/sdb7        20979712    31465471     5242880   fd  Linux raid autodetect
/dev/sdb8        31467520    41943039     5237760   fd  Linux raid autodetect
[root@localhost ~]# partx -a /dev/sdb
partx: /dev/sdb: error adding partition 1
partx: /dev/sdb: error adding partitions 5-8
[root@localhost ~]# cat /proc/partitions
major minor  #blocks  name

   2        0          4 fd0
   8       16   20971520 sdb
   8       17          1 sdb1
   8       21    5242880 sdb5
   8       22    5242880 sdb6
   8       23    5242880 sdb7
   8       24    5237760 sdb8
   8        0  125829120 sda
   8        1    1048576 sda1
   8        2  124779520 sda2
  11        0    4481024 sr0
 253        0   52428800 dm-0
 253        1    2097152 dm-1
 253        2   70246400 dm-2

格式化RAID

[root@localhost ~]# mke2fs -t ext4 -L backUp /dev/md0
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=backUp
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
327680 inodes, 1309440 blocks
65472 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=1342177280
40 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks: 
    32768, 98304, 163840, 229376, 294912, 819200, 884736

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

挂载

[root@localhost ~]# mount -L backUp /backup
[root@localhost ~]# mount
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime,seclabel)
...
/dev/md0 on /backup type ext4 (rw,relatime,seclabel,data=ordered)

设置开机自动挂载

[root@localhost ~]# backUp /backup ext4 defaults 0 0 >> /etc/fstab

A2

组成RAID10

[root@localhost ~]# mdadm -C /dev/md0 -l 10 -n 4 -a yes -c 256K /dev/sdb{5,6,7,8}
mdadm: /dev/sdb5 appears to contain an ext2fs file system
       size=5242880K  mtime=Wed Dec 31 19:00:00 1969
mdadm: /dev/sdb5 appears to be part of a raid array:
       level=raid1 devices=2 ctime=Sun Feb 17 08:35:31 2019
mdadm: /dev/sdb6 appears to contain an ext2fs file system
       size=5242880K  mtime=Wed Dec 31 19:00:00 1969
mdadm: /dev/sdb6 appears to be part of a raid array:
       level=raid1 devices=2 ctime=Sun Feb 17 08:35:31 2019
mdadm: /dev/sdb7 appears to contain an ext2fs file system
       size=5242880K  mtime=Wed Dec 31 19:00:00 1969
mdadm: /dev/sdb7 appears to be part of a raid array:
       level=raid1 devices=2 ctime=Sun Feb 17 08:35:31 2019
mdadm: /dev/sdb8 appears to contain an ext2fs file system
       size=5237760K  mtime=Sun Feb 17 08:40:08 2019
Continue creating array? y
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1] [raid10] 
md0 : active raid10 sdb8[3] sdb7[2] sdb6[1] sdb5[0]
      10465280 blocks super 1.2 256K chunks 2 near-copies [4/4] [UUUU]
      
unused devices: <none>
[root@localhost ~]# mdadm -D /dev/md0
/dev/md0:
           Version : 1.2
     Creation Time : Sun Feb 17 08:58:06 2019
        Raid Level : raid10
        Array Size : 10465280 (9.98 GiB 10.72 GB)
     Used Dev Size : 5232640 (4.99 GiB 5.36 GB)
      Raid Devices : 4
     Total Devices : 4
       Persistence : Superblock is persistent

       Update Time : Sun Feb 17 08:58:21 2019
             State : clean 
    Active Devices : 4
   Working Devices : 4
    Failed Devices : 0
     Spare Devices : 0

            Layout : near=2
        Chunk Size : 256K

Consistency Policy : resync

              Name : localhost.localdomain:0  (local to host localhost.localdomain)
              UUID : 777c686f:0bac4cbb:2ab8268d:585480b0
            Events : 17

    Number   Major   Minor   RaidDevice State
       0       8       21        0      active sync set-A   /dev/sdb5
       1       8       22        1      active sync set-B   /dev/sdb6
       2       8       23        2      active sync set-A   /dev/sdb7
       3       8       24        3      active sync set-B   /dev/sdb8

格式化md0

[root@localhost ~]# mke2fs -t ext4 -L myData /dev/md0
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=myData
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=64 blocks, Stripe width=128 blocks
654080 inodes, 2616320 blocks
130816 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2151677952
80 block groups
32768 blocks per group, 32768 fragments per group
8176 inodes per group
Superblock backups stored on blocks: 
    32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

挂载

root@localhost ~]# mount -L myData /mydata
[root@localhost ~]# fdisk -l /dev/md0

Disk /dev/md0: 10.7 GB, 10716446720 bytes, 20930560 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 262144 bytes / 524288 bytes

设置fstab文件

[root@localhost ~]# myData /mydata ext4 defaults 0 0 >> /etc/fstab

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