磁盘及文件系统管理应用实例

1.创建一个10G的分区，并格式化为ext4文件系统
- 要求其block大小为2048，预留空间百分比为2，卷标为MYDATA，默认挂载属性包含acl
- 挂载至/data/mydata目录，要求挂载时禁止程序自动运行，且不更新文件的访问时间戳

[root@master ~]# fdisk /dev/sdb
    Command (m for help): n   
    Partition type:
      p   primary (0 primary, 0 extended, 4 free)
      e   extended
    Select (default p): p
    Partition number (1-4, default 1): 1
    First sector (2048-41943039, default 2048):
    Using default value 2048
    Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): +10G
    Partition 1 of type Linux and of size 10 GiB is set    
    Command (m for help): w
    The partition table has been altered!

    [root@master ~]# mke2fs -t ext4 -b 2048 -m 2 -L MYDATA  /dev/sdb1
    [root@master ~]# tune2fs -o acl /dev/sdb1

    [root@master ~]# mount -o noexec,noatime /dev/sdb1 /data/mydata

2.创建一个大小为1G的swap分区，并创建好文件系统，并启用之，写一个脚本
- 获取并列出当前系统上的所有磁盘设备
- 显示每个磁盘设备上每个分区的相关的空间使用信息

[root@master ~]# fdisk /dev/sdb
    Command (m for help): n
    Partition type:
       p   primary (1 primary, 0 extended, 3 free)
       e   extended
    Select (default p): p
    Partition number (2-4, default 2): 2
    First sector (20973568-41943039, default 20973568):
    Using default value 20973568
    Last sector, +sectors or +size{K,M,G} (20973568-41943039, default 41943039): +1G
    Partition 2 of type Linux and of size 1 GiB is set
    Command (m for help): t
    Partition number (1,2, default 2): 2
    Hex code (type L to list all codes): L
    Hex code (type L to list all codes): 82
    Changed type of partition 'Linux' to 'Linux swap / Solaris'
    Command (m for help): w
    The partition table has been altered!

    [root@master ~]# mkswap -L SWAP /dev/sdb2
    [root@master ~]# swapon /dev/sdb2

    #!/bin/bash
    #
    disks=`fdisk -l|grep -o '^Disk /dev/[sh]d[a-z]'|cut -d' ' -f2`
    echo $disks
    for i in $disks;do
        fdisk -l $i
    done

3.总结RAID的各个级别及其组合方式和性能的不同
RAID（冗余磁盘阵列）是将多块磁盘当做一块物理磁盘来使用，以达到容错或者提高读写性能的优势。按照组织起来的工作方式的不同，我们可以将RAID分为不同的级别，其中常见的有RAID0、RAID1、RAID5、RAID10
- RAID0
  - 俗称条带卷，实现将文件分成多个chunk后同时并行存储到多个盘中。
  - 特性
```
读写性能得到提升
无冗余能力
最少磁盘数为2
可用空间为容量最小的磁盘*磁盘数
```
- RAID1
  - 俗称镜像卷，在存储数据的同时需要再复制一份存入另一个磁盘中。
  - 特性
```
读性能提升，写性能下降
有冗余能力
最少磁盘数为2，偶数
可用空间小于1/2
```
- RAID5
  - 将文件分成多个chunk，两两chunk之间作异或运算，各盘轮流存储校验码
  - 特点
```
读写性能提升
有冗余能力
最少磁盘数为3
可用空间为容量最小的磁盘*（磁盘数-1）
```
- RAID10
  - 先两两做raid1，后将多组raid1组织成raid0
  - 特点
```
读写性能提升
有冗余能力
最小磁盘数4
可用空间为容量最小的磁盘*磁盘数/2
```

4.创建一个大小为10G的RAID1，要求有一个空闲盘，而且chunk大小为128k

[root@master ~]# fdisk /dev/sdb
  Command (m for help): n
  Partition type:
     p   primary (0 primary, 0 extended, 4 free)
     e   extended
  Select (default p): p
  Partition number (1-4, default 1): 1
  First sector (2048-104857599, default 2048):
  Using default value 2048
  Last sector, +sectors or +size{K,M,G} (2048-104857599, default 104857599): +10G
  Partition 1 of type Linux and of size 10 GiB is set
  Command (m for help): n
  Partition type:
     p   primary (1 primary, 0 extended, 3 free)
     e   extended
  Select (default p): p
  Partition number (2-4, default 2): 2
  First sector (20973568-104857599, default 20973568): +10G
  Value out of range.
  First sector (20973568-104857599, default 20973568):
  Using default value 20973568
  Last sector, +sectors or +size{K,M,G} (20973568-104857599, default 104857599): +10G
  Partition 2 of type Linux and of size 10 GiB is set
  Command (m for help): n
  Partition type:
     p   primary (2 primary, 0 extended, 2 free)
     e   extended
  Select (default p): p
  Partition number (3,4, default 3): 3
  First sector (41945088-104857599, default 41945088):
  Using default value 41945088
  Last sector, +sectors or +size{K,M,G} (41945088-104857599, default 104857599): +10G
  Partition 3 of type Linux and of size 10 GiB is set
  Command (m for help): t
  Partition number (1-3, default 3): 1
  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 (1-3, default 3): 2
  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 (1-3, default 3): 3
  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!

  [root@master ~]# mdadm -C /dev/md0 -n 2 -c 128 -x 1 -l 1 -a yes /dev/sdb{1,2,3}
  mdadm: Defaulting to version 1.2 metadata
  mdadm: array /dev/md0 started.

5.创建一个大小为4G的RAID5设备，chunk大小为256k，格式化ext4文件系统，要求可开机自动挂载至/backup目录，且不更新访问时间戳，且支持acl功能
“`

[root@master ~]# fdisk /dev/sdb
  Command (m for help): n
  All primary partitions are in use
  Adding logical partition 5
  First sector (62918656-104857599, default 62918656):
  Using default value 62918656
  Last sector, +sectors or +size{K,M,G} (62918656-104857599, default 104857599): +2G
  Partition 5 of type Linux and of size 2 GiB is set
  Command (m for help): n
  All primary partitions are in use
  Adding logical partition 6
  First sector (67115008-104857599, default 67115008):
  Using default value 67115008
  Last sector, +sectors or +size{K,M,G} (67115008-104857599, default 104857599): +2G
  Partition 6 of type Linux and of size 2 GiB is set
  Command (m for help): n
  All primary partitions are in use
  Adding logical partition 7
  First sector (71311360-104857599, default 71311360):
  Using default value 71311360
  Last sector, +sectors or +size{K,M,G} (71311360-104857599, default 104857599): +2G
  Partition 7 of type Linux and of size 2 GiB is set
  Command (m for help): w
  The partition table has been altered!

  [root@master ~]# mdadm -C /dev/md1 -n 3 -c 256  -l 5 -a yes /dev/sdb{5,6,7}
  mdadm: Defaulting to version 1.2 metadata
  mdadm: array /dev/md1 started.

  [root@master ~]# mke2fs -t ext4  /dev/md1
  [root@master ~]# mkdir /backup
  [root@master ~]# mount -o auto /dev/md1 /backup

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