标签：M55 RAID No dev CentOS7 part 64 sdb root
2021-5-27
1.MBR修复
dd命令详解：
[root@centos6 ~]# dd --help
Usage: dd [OPERAND]...
or: dd OPTION
Copy a file, converting and formatting according to the operands.
bs=BYTES #一次读写块大小
cbs=BYTES convert BYTES bytes at a time
conv=CONVS convert the file as per the comma separated symbol list
count=N copy only N input blocks
ibs=BYTES read BYTES bytes at a time (default: 512)
if=FILE #输入文件名，缺省为标准输入
iflag=FLAGS read as per the comma separated symbol list
obs=BYTES write BYTES bytes at a time (default: 512)
of=FILE #输出文件名，缺省为标准输出
oflag=FLAGS write as per the comma separated symbol list
seek=BLOCKS #从输出文件开头跳过blocks个块后再开始复制
skip=BLOCKS #从输入文件开头跳过blocks个块后再开始复制
status=WHICH WHICH info to suppress outputting to stderr;
'noxfer' suppresses transfer stats, 'none' suppresses all
# skip是跳过if中的前多少字节
# seek是跳过of中的前多少字节
一、备份分区文件：
[root@localhost ~]# dd if=/dev/sda of=/data/dpt.img bs=1 count=64 skip=446
[root@localhost ~]# scp /data/dpt.img 10.0.0.6:
二、模拟破坏分区：
索引部分任意地方破导致启动不了，只备份446开始的64字节，破坏这64字节内容
[root@localhost ~]# dd if=/dev/zero of=/dev/sda bs=1 count=64 seek=446
三、救援
reboot
进入光盘救援模式，选择3直接进入shell环境。备注：选1会出错，硬盘挂载不起来
配置临时网络（此时没有网络）
ifconfig ens eth0（看ifconfig中失效网卡） 10.0.0.6/24
scp 10.0.0.16: /root/dpt.img
dd if=dpt.img of=/dev/sda bs=1 seek=446
exit
实战：模拟破坏mbr表并修复
#1.备份MBR分区表
[root@centos6 ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sr0 11:0 1 406M 0 rom
sda 8:0 0 200G 0 disk
├─sda1 8:1 0 500M 0 part /boot
└─sda2 8:2 0 199.5G 0 part
├─vg_centos6-lv_root (dm-0) 253:0 0 50G 0 lvm /
├─vg_centos6-lv_swap (dm-1) 253:1 0 3.9G 0 lvm [SWAP]
└─vg_centos6-lv_home (dm-2) 253:2 0 145.6G 0 lvm /home
[root@centos6 ~]# dd if=/dev/sda of=/tmp/dpt.img bs=1 count=64 skip=446
64+0 records in
64+0 records out
64 bytes (64 B) copied, 0.000830782 s, 77.0 kB/s
[root@centos6 ~]# scp /tmp/dpt.img 10.0.0.6:
The authenticity of host '10.0.0.6 (10.0.0.6)' can't be established.
RSA key fingerprint is ad:ce:fa:ec:a7:6d:0d:d1:90:92:e9:d1:b5:b3:79:46.
Are you sure you want to continue connecting (yes/no)? y
Please type 'yes' or 'no': yes
Warning: Permanently added '10.0.0.6' (RSA) to the list of known hosts.
root@10.0.0.6's password:
dpt.img 100% 64 0.1KB/s 00:00
#2.破坏MBR分区表
[root@centos6 ~]# dd if=/dev/zero of=/dev/sda bs=1 count=64 seek=446
64+0 records in
64+0 records out
64 bytes (64 B) copied, 0.000832751 s, 76.9 kB/s
[root@centos6 ~]# reboot
#3.之后无法正常启动，进入grub>;
#重启系统快速按F2键，进入BIOS界面，选择Boot选项，将光盘‘CD-ROM Drive’设置为第一个优先启动，F10保存
#4.进入救援模式‘rescue mode’,选择第3项 'skip to shell'
sh-4.1# ifconfig eth0 10.0.0.16/24
sh-4.1# scp 10.0.0.6:/root/dpt.img .
sh-4.1# dd if=dpt.img of=/dev/sda bs=1 seek=446
sh-4.1# exit
2.RAID级别及组合方式和性能
RAID介绍
RAID:Redundant Arrays of Inexpensive Disks,廉价磁盘冗余阵列。
多个磁盘组合成一个阵列提供更好的性能、冗余，或者两者都提供。
RAID级别及组合方式和性能
RAID-0 #以chunk为单位，读写数据，读、写性能提升，最少磁盘数：2,2+，无容错能力
RAID-1 #读性能提升，写性能略有下降，有冗余能力，最少磁盘数：2,2N
RAID-4 #多块数据盘异或运算值存于专用校验盘，有冗余能力，至少3块硬盘实现
RAID-5 #读、写性能提升、有容错能力：允许最多1块磁盘损坏，最少磁盘数：3,3+
RAID-6 #读、写性能提升、有容错能力：允许最多2块磁盘损坏，最少磁盘数：4,4+
RAID-10 #读、写性能提升、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 #多块磁盘先实现RAID0，再组合成RAID1
RAID-50 #多块磁盘先实现RAID5，再组合成RAID0
3.创建文件系统
磁盘及文件系统基本命令介绍：
#磁盘分区等相关命令：
lsblk： #列出块设备信息（list block devices） -f输出文件系统信息
blkid： #打印块设备属性
fdisk： #操作磁盘分区表
pvcreate： #初始化LVM使用的物理卷
mkfs.ext4： #创建一个ext4文件系统
mount： #挂载一个文件系统到分区表
vgcreate： #创建一个卷组
vgs： #显示卷组信息
lvcreate： #创建一个逻辑卷
lvs： #显示逻辑卷信息
实战：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
#1.新增一个20G大小的sdb硬盘，做实验操作
[root@CentOS7 ~]# 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 [SWAP]
└─sda3 8:3 0 100G 0 part /
sdb 8:16 0 20G 0 disk
sr0 11:0 1 4G 0 rom
#2.在sdb上创建2G分区
[root@centos6 ~]# fdisk /dev/sdb
Command (m for help): m
Command action
a toggle a bootable flag
b edit bsd disklabel
c toggle the dos compatibility flag
d delete a partition
g create a new empty GPT partition table
G create an IRIX (SGI) partition table
l list known partition types
m print this menu
n add a new partition
o create a new empty DOS partition table
p print the partition table
q quit without saving changes
s create a new empty Sun disklabel
t change a partition's system id
u change display/entry units
v verify the partition table
w write table to disk and exit
x extra functionality (experts only)
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):
First sector (2048-41943039, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): +2G
Partition 1 of type Linux and of size 2 GiB is set
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
#3.在sdb分区上创建文件系统
[root@CentOS7 ~]# mkfs.ext4 -b 2048 -m 1 -L TEST /dev/sdb1
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=TEST
OS type: Linux
Block size=2048 (log=1)
Fragment size=2048 (log=1)
Stride=0 blocks, Stripe width=0 blocks
131072 inodes, 1048576 blocks
10485 blocks (1.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=269484032
64 block groups
16384 blocks per group, 16384 fragments per group
2048 inodes per group
Superblock backups stored on blocks:
16384, 49152, 81920, 114688, 147456, 409600, 442368, 802816
Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
#4.查看分区结果
[root@CentOS7 ~]# blkid
/dev/sda1: UUID="9a8e98ca-f998-4af2-9dae-28a78e2e4838" TYPE="xfs"
/dev/sda2: UUID="bbb7b1c6-74d0-499b-8d71-7b6240b0fcb5" TYPE="swap"
/dev/sda3: UUID="14e56b7c-4eff-4c7d-bf27-0d1ec866a3fb" TYPE="xfs"
/dev/sdb1: LABEL="TEST" UUID="e84464e9-70bb-4c87-869e-7e2e3e8a5c76" TYPE="ext4"
/dev/sr0: UUID="2015-12-09-23-14-10-00" LABEL="CentOS 7 x86_64" TYPE="iso9660" PTTYPE="dos"
[root@CentOS7 ~]# 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 [SWAP]
└─sda3 8:3 0 100G 0 part /
sdb 8:16 0 20G 0 disk
└─sdb1 8:17 0 2G 0 part
sr0 11:0 1 4G 0 rom
#5.将分区挂载到指定文件夹/test
[root@CentOS7 ~]# mkdir /test
[root@CentOS7 ~]# echo 'UUUUID=e84464e9-70bb-4c87-869e-7e2e3e8a5c76 /test ext4 acl 0 0' >> /etc/fstab
[root@CentOS7 ~]# cat /etc/fstab
#
# /etc/fstab
# Created by anaconda on Tue Apr 20 21:28:17 2021
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=14e56b7c-4eff-4c7d-bf27-0d1ec866a3fb / xfs defaults 0 0
UUID=9a8e98ca-f998-4af2-9dae-28a78e2e4838 /boot xfs defaults 0 0
UUID=bbb7b1c6-74d0-499b-8d71-7b6240b0fcb5 swap swap defaults 0 0
UUUUID=e84464e9-70bb-4c87-869e-7e2e3e8a5c76 /test ext4 acl 0 0
#6.使挂载生效
[root@CentOS7 ~]# mount -a
#7.查看挂载文件系统
[root@CentOS7 ~]# 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 [SWAP]
└─sda3 8:3 0 100G 0 part /
sdb 8:16 0 20G 0 disk
└─sdb1 8:17 0 2G 0 part /test
sr0 11:0 1 4G 0 rom
实战：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
#1.查看磁盘，新增了一个10G盘sdc
[root@CentOS7 ~]# 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 [SWAP]
└─sda3 8:3 0 100G 0 part /
sdb 8:16 0 20G 0 disk
└─sdb1 8:17 0 2G 0 part /test
sdc 8:32 0 10G 0 disk
sr0 11:0 1 4G 0 rom
#2.在sdc创建10G分区
[root@CentOS7 ~]# fdisk /dev/sdc
Welcome to fdisk (util-linux 2.23.2).
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p):
Using default response p
Partition number (1-4, default 1):
First sector (2048-20971519, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519): +10G
Value out of range.
Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519): +9G
Partition 1 of type Linux and of size 9 GiB is set
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: 10.7 GB, 10737418240 bytes, 20971520 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: 0x625894bd
Device Boot Start End Blocks Id System
/dev/sdc1 2048 18876415 9437184 8e Linux LVM
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
#3.在sdc1分区和sdb上分别创建物理卷（PV）
#pvcreate依赖包lvm2-2.02.180-10.el7_6.8.x86_64
[root@CentOS7 ~]# yum provides pvcreate
7:lvm2-2.02.180-10.el7_6.8.x86_64 : Userland logical volume management tools
Repo : update
Matched from:
Filename : /usr/sbin/pvcreate
[root@CentOS7 ~]# yum -y install lvm2-2.02.180-10.el7_6.8.x86_64
#4.在sdc1分区和sdb上分别创建物理卷（pv）
[root@CentOS7 ~]# pvcreate /dev/sdc1
Physical volume "/dev/sdc1" successfully created.
[root@CentOS7 ~]# pvcreate /dev/sdb
WARNING: dos signature detected on /dev/sdb at offset 510. Wipe it? [y/n]: y
Wiping dos signature on /dev/sdb.
Physical volume "/dev/sdb" successfully created.
[root@CentOS7 ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sdb lvm2 --- 20.00g 20.00g
/dev/sdc1 lvm2 --- 9.00g 9.00g
#5.创建物理卷组testvg（vg）,并将创建的pv加入其中
[root@CentOS7 ~]# vgcreate -s 16M testvg /dev/sdb /dev/sdc1
Volume group "testvg" successfully created
[root@CentOS7 ~]# vgs
VG #PV #LV #SN Attr VSize VFree
testvg 2 0 0 wz--n- <28.97g <28.97g
#6.在testvg中创建大小为5G的逻辑卷（LV）
[root@CentOS7 ~]# lvcreate -n testlv -L 5G testvg
WARNING: ext4 signature detected on /dev/testvg/testlv at offset 1080. Wipe it? [y/n]: y
Wiping ext4 signature on /dev/testvg/testlv.
Logical volume "testlv" created.
[root@CentOS7 ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
testlv testvg -wi-a----- 5.00g
#6.创建文件系统
[root@CentOS7 ~]# mkfs.ext4 /dev/testvg/testlv
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
327680 inodes, 1310720 blocks
65536 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
#7.确认BLKID并加入/etc/fstab
[root@CentOS7 ~]# blkid
/dev/sda1: UUID="9a8e98ca-f998-4af2-9dae-28a78e2e4838" TYPE="xfs"
/dev/sda2: UUID="bbb7b1c6-74d0-499b-8d71-7b6240b0fcb5" TYPE="swap"
/dev/sda3: UUID="14e56b7c-4eff-4c7d-bf27-0d1ec866a3fb" TYPE="xfs"
/dev/sdb: UUID="nQf48z-QM6T-QTXA-MwWj-G44h-XQbq-x9wMie" TYPE="LVM2_member"
/dev/sdc1: UUID="WqmKbk-4Ka4-1OQO-JoHt-iHY3-A7RO-ke9Y7U" TYPE="LVM2_member"
/dev/sr0: UUID="2015-12-09-23-14-10-00" LABEL="CentOS 7 x86_64" TYPE="iso9660" PTTYPE="dos"
/dev/mapper/testvg-testlv: UUID="9e33092d-7dd0-41b8-b576-337cc13c6ee8" TYPE="ext4"
[root@CentOS7 ~]# echo 'UUID=9e33092d-7dd0-41b8-b576-337cc13c6ee8 /users ext4 defaults 0 0' >> /etc/fstab
[root@CentOS7 ~]# cat /etc/fstab
#
# /etc/fstab
# Created by anaconda on Tue Apr 20 21:28:17 2021
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=14e56b7c-4eff-4c7d-bf27-0d1ec866a3fb / xfs defaults 0 0
UUID=9a8e98ca-f998-4af2-9dae-28a78e2e4838 /boot xfs defaults 0 0
UUID=bbb7b1c6-74d0-499b-8d71-7b6240b0fcb5 swap swap defaults 0 0
UUID=9e33092d-7dd0-41b8-b576-337cc13c6ee8 /users ext4 defaults 0 0
#8.创建文件夹，并让其生效
[root@CentOS7 ~]# mkdir /users
[root@CentOS7 ~]# mount -a
4.网络模型
实战：简述osi七层模型和TCP/IP五层模型
#OSI七层网络模型
1.应用层 #提供网络服务和接口，协议有HTTP,FTP等
2.表示层 #数据的表示、安全、压缩，格式有JPEG,ASCII、加密格式等
3.会话层 #建立、管理、终止会话，对应主机进程正在进行的会话
4.传输层 #定义传输数据的协议端口号，以及流控和差错校验，协议有TCP,UDP等
5.网络层 #进行逻辑地址寻址，实现不同网络间路径选择，协议有ICMP,IP等
6.数据链路层 #建立逻辑连接，进行硬件寻址，差错校验，如用MAC访问介质
7.物理层 #建立、维护、断开物理连接
#TCP/IP五层模型
1.应用层 #对应OSI的应用层，表示层，会话层
2.传输层 #对应OSI的传输层
3.网络层 #对应OSI的网络层
4.数据链路层 #对应OSI的数据链路层
5.物理层 #对应OSI的物理层标签：M55,RAID,No,dev,CentOS7,part,64,sdb,root 来源： https://www.cnblogs.com/hony625/p/14816617.html
本站声明： 1. iCode9 技术分享网（下文简称本站）提供的所有内容，仅供技术学习、探讨和分享； 2. 关于本站的所有留言、评论、转载及引用，纯属内容发起人的个人观点，与本站观点和立场无关； 3. 关于本站的所有言论和文字，纯属内容发起人的个人观点，与本站观点和立场无关； 4. 本站文章均是网友提供，不完全保证技术分享内容的完整性、准确性、时效性、风险性和版权归属；如您发现该文章侵犯了您的权益，可联系我们第一时间进行删除； 5. 本站为非盈利性的个人网站，所有内容不会用来进行牟利，也不会利用任何形式的广告来间接获益，纯粹是为了广大技术爱好者提供技术内容和技术思想的分享性交流网站。