1、破坏mbr表并修复
备份MBR分区表
[root@centos8 ~]#dd if=/dev/sda of=/data/dpt.img bs=1 count=64 skip=446
[root@centos8 ~]#scp /data/dpt.img 10.0.0.102:
破坏MBR分区表
[root@centos8 ~]#dd if=/dev/zero of=/dev/sda bs=1 count=64 seek=446（把分区表都写成0）
重启后无法启动系统
[root@centos8 ~]#reboot
用光盘启动,进入rescue mode,选第3项skip to shell
配置网络
#ifconfig ens160 10.0.0.8/24
#ip a a 10.0.0.8/24 dev/ens160
#scp 10.0.0.102:/root/dpt.img .
恢复MBR分区表
#dd if=dpt.img of=/dev/sda bs=1 seek=446
#exit
2、总结RAID的各个级别及其组合方式和性能的不同。
级别：多块磁盘组织在一起的工作方式有所不同
RAID-0：条带卷，strip，无容错能力，最少2块磁盘，读写性能提升
RAID-1：镜像卷，mirror，1/2空间，读性能提升，写性能略下降，最少2块磁盘
RAID-4：多块数据盘异或运算值存于专用校验盘，磁盘利用率 n-1/n，有冗余，至少3块磁盘
raid5 磁盘利用率 n-1/n 最少3块磁盘
raid6 磁盘利用率 n-2/n 最少4块磁盘
raid7 可以理解为一个独立存储计算机，自身带有操作系统和管理工具，可以独立运行，理论上性能最高的
raid10 磁盘利用率 1/2，先两两组合成raid1，再把这2组raid1组成raid0，最少4块磁盘，每组镜像最多坏1个磁盘，系统失败的几率是1/3
raid01 磁盘利用率 1/2，先两两组合成raid0，再把这2组raid0组成raid1，最少4块磁盘，系统失败几率是2/3.
raid50 先做成raid5，再做成raid0
JBOD：单纯的把几个硬盘组合成一个逻辑的大硬盘，没有其他作用。
3、创建一个2G的文件系统，块大小为2048byte，预留1%可用空间,文件系统 ext4，卷标为TEST，要求此分区开机后自动挂载至/test目录，且默认有acl挂载选项
[root@centos8 ~]# fdisk -l /dev/sdb #从/dev/sdb创建一个文件系统
[root@centos7 ~]# mke2fs -t ext4 -b 2048 -L 'TEST' -m 1 /dev/sdb1 #创建卷标为TEST格式为ext4的预留1%可用空间的文件系统
[root@centos7 ~]# blkid #查看新创建的文件系统的UUID
[root@centos7 ~]# vim /etc/fstab #写入fatab文件
4、创建一个至少有两个PV组成的大小为20G的名为testvg的VG;要求PE大小 为16MB, 而后在卷组中创建大小为5G的逻辑卷testlv;挂载至/users目录
查看当期那硬盘信息
[19:39:49 root@etcd3 ~]#lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 200G 0 disk
├─sda1 8:1 0 1G 0 part /boot
├─sda2 8:2 0 4G 0 part
└─sda3 8:3 0 195G 0 part /
sdb 8:16 0 20G 0 disk
sdc 8:32 0 20G 0 disk
sr0 11:0 1 7.7G 0 rom
开始编辑/devsdb，创建1个10G的分区
[19:39:53 root@etcd3 ~]#fdisk /dev/sdb
Welcome to fdisk (util-linux 2.32.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table.
Created a new DOS disklabel with disk identifier 0x1a14949a.
Command (m for help): n
Partition type
p primary (0 primary, 0 extended, 4 free)
e extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1):
First sector (2048-41943039, default 2048):
Last sector, +sectors or +size{K,M,G,T,P} (2048-41943039, default 41943039): +10G
Created a new partition 1 of type 'Linux' and of size 10 GiB.
Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'.
Command (m for help): p
Disk /dev/sdb: 20 GiB, 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
Disklabel type: dos
Disk identifier: 0x1a14949a
Device Boot Start End Sectors Size Id Type
/dev/sdb1 2048 20973567 20971520 10G 8e Linux LVM
Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
在/dev/sdc创建一个10G的分区
[19:41:10 root@etcd3 ~]#fdisk /dev/sdc
Welcome to fdisk (util-linux 2.32.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table.
Created a new DOS disklabel with disk identifier 0xbfcf6ce6.
Command (m for help): n
Partition type
p primary (0 primary, 0 extended, 4 free)
e extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1):
First sector (2048-41943039, default 2048):
Last sector, +sectors or +size{K,M,G,T,P} (2048-41943039, default 41943039): +10G
Created a new partition 1 of type 'Linux' and of size 10 GiB.
Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'.
Command (m for help): p
Disk /dev/sdc: 20 GiB, 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
Disklabel type: dos
Disk identifier: 0xbfcf6ce6
Device Boot Start End Sectors Size Id Type
/dev/sdc1 2048 20973567 20971520 10G 8e Linux LVM
Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
创建完成后继续查看分区信息
[19:43:07 root@etcd3 ~]#lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 200G 0 disk
├─sda1 8:1 0 1G 0 part /boot
├─sda2 8:2 0 4G 0 part
└─sda3 8:3 0 195G 0 part /
sdb 8:16 0 20G 0 disk
└─sdb1 8:17 0 10G 0 part
sdc 8:32 0 20G 0 disk
└─sdc1 8:33 0 10G 0 part
sr0 11:0 1 7.7G 0 rom
在/dev/sdb1和/dev/sdc1上创建物理卷
[19:43:25 root@etcd3 ~]#pvcreate /dev/sdb1
Physical volume "/dev/sdb1" successfully created.
[19:46:13 root@etcd3 ~]#pvcreate /dev/sdc1
Physical volume "/dev/sdc1" successfully created.
创建物理卷组，将上面的物理卷加入其中
[19:46:17 root@etcd3 ~]#vgcreate -s 16M testvg /dev/sdb1 /dev/sdc1
Volume group "testvg" successfully created
[19:47:35 root@etcd3 ~]#vgs
VG #PV #LV #SN Attr VSize VFree
testvg 2 0 0 wz--n- <19.97g <19.97g
在testvgz中创建大小为5G的逻辑卷
[19:47:38 root@etcd3 ~]#lvcreate -n testlv -L 5G testvg
Logical volume "testlv" created.
[19:49:01 root@etcd3 ~]#lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
testlv testvg -wi-a----- 5.00g
创建文件系统
[19:49:06 root@etcd3 ~]#mkfs.ext4 /dev/testvg/testlv
mke2fs 1.45.4 (23-Sep-2019)
Creating filesystem with 1310720 4k blocks and 327680 inodes
Filesystem UUID: a85dca48-8dc0-474e-81c9-dbe1d2476833
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736
Allocating group tables: done
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done
查看新创建的逻辑卷的UUID
[19:49:44 root@etcd3 ~]#blkid
/dev/sda1: UUID="d748f17d-7af2-4187-a919-bcbdfc3267e3" TYPE="ext4" PARTUUID="67bc259b-01"
/dev/sda2: UUID="5847e7d9-47ab-4d4a-8179-ffd024a2fa99" TYPE="swap" PARTUUID="67bc259b-02"
/dev/sda3: UUID="642d007c-6670-4c6f-828f-054866c78a31" TYPE="xfs" PARTUUID="67bc259b-03"
/dev/sr0: UUID="2020-06-08-22-08-25-00" LABEL="CentOS-8-2-2004-x86_64-dvd" TYPE="iso9660" PTUUID="545ce9a4" PTTYPE="dos"
/dev/sdb1: UUID="zh2ivK-RPfl-7Zpe-tfvb-bVYa-ddcw-k3UHYf" TYPE="LVM2_member" PARTUUID="1a14949a-01"
/dev/sdc1: UUID="Pfzulg-sKJr-FvKn-7ePE-ur0W-l25R-c7vnaM" TYPE="LVM2_member" PARTUUID="bfcf6ce6-01"
/dev/mapper/testvg-testlv: UUID="a85dca48-8dc0-474e-81c9-dbe1d2476833" TYPE="ext4"
创建users目录
[19:51:58 root@etcd3 ~]#mkdir /users
在/etc/fatab配置文件中添加UUID
[19:52:28 root@etcd3 ~]#vim /etc/fstab
UUID=642d007c-6670-4c6f-828f-054866c78a31 / xfs defaults 0 0
UUID=d748f17d-7af2-4187-a919-bcbdfc3267e3 /boot ext4 defaults 1 2
UUID=5847e7d9-47ab-4d4a-8179-ffd024a2fa99 swap swap defaults 0 0
UUID=a85dca48-8dc0-474e-81c9-dbe1d2476833 /users ext4 defaults 0 0
挂载
[19:55:23 root@etcd3 ~]#mount -a
查看
[19:55:27 root@etcd3 ~]#lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 200G 0 disk
├─sda1 8:1 0 1G 0 part /boot
├─sda2 8:2 0 4G 0 part
└─sda3 8:3 0 195G 0 part /
sdb 8:16 0 20G 0 disk
└─sdb1 8:17 0 10G 0 part
└─testvg-testlv 253:0 0 5G 0 lvm /users
sdc 8:32 0 20G 0 disk
└─sdc1 8:33 0 10G 0 part
sr0 11:0 1 7.7G 0 rom
[19:55:32 root@etcd3 ~]#df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 460M 0 460M 0% /dev
tmpfs 477M 0 477M 0% /dev/shm
tmpfs 477M 6.7M 470M 2% /run
tmpfs 477M 0 477M 0% /sys/fs/cgroup
/dev/sda3 195G 2.8G 193G 2% /
/dev/sda1 976M 118M 792M 13% /boot
tmpfs 96M 0 96M 0% /run/user/0
/dev/mapper/testvg-testlv 4.9G 20M 4.6G 1% /users