1、破坏mbr表并修复
##先做分区表备份
[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 100G 0 part /
├─sda3 8:3 0 50G 0 part /data
├─sda4 8:4 0 1K 0 part
└─sda5 8:5 0 2G 0 part [SWAP]
sr0 11:0 1 4.5G 0 rom
[root@centos7 ~]# dd if=/dev/sda of=/data/dpt.img bs=1 count=64 skip=446
64+0 records in
64+0 records out
64 bytes (64 B) copied, 0.000314256 s, 204 kB/s
[root@centos7 ~]# ll /data/dpt.img
-rw-r--r--. 1 root root 64 Feb 23 14:42 /data/dpt.img
##备份到远程主机
[root@centos7 ~]# scp /data/dpt.img 10.0.0.203:/data/
The authenticity of host '10.0.0.203 (10.0.0.203)' can't be established.
ECDSA key fingerprint is SHA256:rB9N78xM2IfAKqhHahltwZEBmHEMhToDY/caJDmuycs.
ECDSA key fingerprint is MD5:29:2c:59:55:59:c8:e9:b4:db:f1:09:ea:19:c2:47:bb.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '10.0.0.203' (ECDSA) to the list of known hosts.
root@10.0.0.203's password:
dpt.img 100% 64 5.2KB/s 00:00
[root@centos8 ~]# ll /data/dpt.img
-rw-r--r--. 1 root root 64 Feb 23 14:49 /data/dpt.img
##破坏mbr分区表
[root@centos7 ~]# 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, 0.00024709 s, 259 kB/s
[root@centos7 ~]# hexdump -C -n 512 /dev/sda -v
00000000 eb 63 90 10 8e d0 bc 00 b0 b8 00 00 8e d8 8e c0 |.c..............|
00000010 fb be 00 7c bf 00 06 b9 00 02 f3 a4 ea 21 06 00 |...|.........!..|
00000020 00 be be 07 38 04 75 0b 83 c6 10 81 fe fe 07 75 |....8.u........u|
00000030 f3 eb 16 b4 02 b0 01 bb 00 7c b2 80 8a 74 01 8b |.........|...t..|
00000040 4c 02 cd 13 ea 00 7c 00 00 eb fe 00 00 00 00 00 |L.....|.........|
00000050 00 00 00 00 00 00 00 00 00 00 00 80 01 00 00 00 |................|
00000060 00 00 00 00 ff fa 90 90 f6 c2 80 74 05 f6 c2 70 |...........t...p|
00000070 74 02 b2 80 ea 79 7c 00 00 31 c0 8e d8 8e d0 bc |t....y|..1......|
00000080 00 20 fb a0 64 7c 3c ff 74 02 88 c2 52 be 05 7c |. ..d|<.t...R..||
00000090 b4 41 bb aa 55 cd 13 5a 52 72 3d 81 fb 55 aa 75 |.A..U..ZRr=..U.u|
000000a0 37 83 e1 01 74 32 31 c0 89 44 04 40 88 44 ff 89 |7...t21..D.@.D..|
000000b0 44 02 c7 04 10 00 66 8b 1e 5c 7c 66 89 5c 08 66 |D.....f..\|f.\.f|
000000c0 8b 1e 60 7c 66 89 5c 0c c7 44 06 00 70 b4 42 cd |..`|f.\..D..p.B.|
000000d0 13 72 05 bb 00 70 eb 76 b4 08 cd 13 73 0d 5a 84 |.r...p.v....s.Z.|
000000e0 d2 0f 83 de 00 be 85 7d e9 82 00 66 0f b6 c6 88 |.......}...f....|
000000f0 64 ff 40 66 89 44 04 0f b6 d1 c1 e2 02 88 e8 88 |d.@f.D..........|
00000100 f4 40 89 44 08 0f b6 c2 c0 e8 02 66 89 04 66 a1 |.@.D.......f..f.|
00000110 60 7c 66 09 c0 75 4e 66 a1 5c 7c 66 31 d2 66 f7 |`|f..uNf.\|f1.f.|
00000120 34 88 d1 31 d2 66 f7 74 04 3b 44 08 7d 37 fe c1 |4..1.f.t.;D.}7..|
00000130 88 c5 30 c0 c1 e8 02 08 c1 88 d0 5a 88 c6 bb 00 |..0........Z....|
00000140 70 8e c3 31 db b8 01 02 cd 13 72 1e 8c c3 60 1e |p..1......r...`.|
00000150 b9 00 01 8e db 31 f6 bf 00 80 8e c6 fc f3 a5 1f |.....1..........|
00000160 61 ff 26 5a 7c be 80 7d eb 03 be 8f 7d e8 34 00 |a.&Z|..}....}.4.|
00000170 be 94 7d e8 2e 00 cd 18 eb fe 47 52 55 42 20 00 |..}.......GRUB .|
00000180 47 65 6f 6d 00 48 61 72 64 20 44 69 73 6b 00 52 |Geom.Hard Disk.R|
00000190 65 61 64 00 20 45 72 72 6f 72 0d 0a 00 bb 01 00 |ead. Error......|
000001a0 b4 0e cd 10 ac 3c 00 75 f4 c3 00 00 00 00 00 00 |.....<.u........|
000001b0 00 00 00 00 00 00 00 00 b4 a5 03 00 00 00 00 00 |................|
000001c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000001d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000001e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000001f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 aa |..............U.|
00000200
重置设备在救援模式下恢复
然后重新启动设备就OK了。
2、总结RAID的各个级别及其组合方式和性能的不同
1）RAID0特性：
读写性能提升；
可用空间，N*min；
无容错能力；
最小磁盘数2
2）RAID1特性：
读性能提升，写性能略有下降，同一份数据要存两份；
可用空间，n/2*min,磁盘总空间的一半；
有冗余能力；
最少磁盘数，2
3）RAID5特性：
读写性能提升；
可用空间，N-1*min；
有冗余能力；
最少磁盘数，3
4）RAID10特性：
读写性能提升；
可用空间，N*min/2;
有冗余能力，每组镜像最多只能坏一块；
最少磁盘数，4
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
##创建文件系统
[root@centos7 ~]# dd if=/dev/zero of=/disk.img bs=2M count=1024
1024+0 records in
1024+0 records out
2147483648 bytes (2.1 GB) copied, 36.1938 s, 59.3 MB/s
[root@centos7 ~]# du -sh /disk.img
2.0G /disk.img
[root@centos7 ~]# mkfs.ext4 -b 2048 -m 1 -L TEST /disk.img
mke2fs 1.42.9 (28-Dec-2013)
/disk.img is not a block special device.
Proceed anyway? (y,n) y
Discarding device blocks: done
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
[root@centos7 ~]# blkid /disk.img
/disk.img: LABEL="TEST" UUID="347a6916-5318-49fa-ac00-14db874a0fbf" TYPE="ext4"
##写入/etc/fstab文件，实现开机自动挂载
[root@centos7 ~]# vim /etc/fstab
[root@centos7 ~]# cat /etc/fstab
UUID=09e19907-d211-4ea5-9057-f90351aa5499 swap swap defaults 0 0
/disk.img /test ext4 loop,acl 0 0
[root@centos7 ~]# mkdir /test
[root@centos7 ~]# mount -a
[root@centos7 ~]# losetup -a
/dev/loop0: [2050]:367930 (/disk.img)
[root@centos7 ~]# lsblk -f
NAME FSTYPE LABEL UUID MOUNTPOINT
sda
├─sda1 xfs 4fa848f3-02f9-4814-8fdb-f41a6d59fc33 /boot
├─sda2 xfs 81d93980-4fd1-4183-9a76-c707bccccc45 /
├─sda3 xfs 2f8ce926-5155-4f92-8025-ecbf34a7aa40 /data
├─sda4
└─sda5 swap 09e19907-d211-4ea5-9057-f90351aa5499 [SWAP]
sr0 iso9660 CentOS 7 x86_64 2020-04-22-00-54-00-00
loop0 ext4 TEST 347a6916-5318-49fa-ac00-14db874a0fbf /test
[root@centos7 ~]# cp /etc/issue /test
[root@centos7 ~]# ll /test
total 18
-rw-r--r--. 1 root root 23 Mar 7 13:54 issue
drwx------. 2 root root 16384 Mar 7 13:39 lost+found
##重启设备之后再查看/test目录下的内容
[root@centos7 ~]# lsblk -f
NAME FSTYPE LABEL UUID MOUNTPOINT
sda
├─sda1 xfs 4fa848f3-02f9-4814-8fdb-f41a6d59fc33 /boot
├─sda2 xfs 81d93980-4fd1-4183-9a76-c707bccccc45 /
├─sda3 xfs 2f8ce926-5155-4f92-8025-ecbf34a7aa40 /data
├─sda4
└─sda5 swap 09e19907-d211-4ea5-9057-f90351aa5499 [SWAP]
sr0 iso9660 CentOS 7 x86_64 2020-04-22-00-54-00-00
loop0 ext4 TEST 347a6916-5318-49fa-ac00-14db874a0fbf /test
[root@centos7 ~]# ll /test
total 18
-rw-r--r--. 1 root root 23 Mar 7 13:54 issue
drwx------. 2 root root 16384 Mar 7 13:39 lost+found
[root@centos7 ~]# tune2fs -l /disk.img
tune2fs 1.42.9 (28-Dec-2013)
Filesystem volume name: TEST ##卷标TEST
Last mounted on: /test
Filesystem UUID: 347a6916-5318-49fa-ac00-14db874a0fbf
Filesystem magic number: 0xEF53
Filesystem revision #: 1 (dynamic)
Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery extent 64bit flex_bg sparse_super huge_file uninit_bg dir_nlink extra_isize
Filesystem flags: signed_directory_hash
Default mount options: user_xattr acl ##acl功能
Filesystem state: clean
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 131072
Block count: 1048576
Reserved block count: 10485 ##预留1%的空间
Free blocks: 994650
Free inodes: 131060
First block: 0
Block size: 2048 ##块大小2048
Fragment size: 2048
Group descriptor size: 64
Reserved GDT blocks: 512
Blocks per group: 16384
Fragments per group: 16384
Inodes per group: 2048
Inode blocks per group: 256
Flex block group size: 16
Filesystem created: Sun Mar 7 13:39:02 2021
Last mount time: Sun Mar 7 13:57:17 2021
Last write time: Sun Mar 7 13:57:17 2021
Mount count: 2
Maximum mount count: -1
Last checked: Sun Mar 7 13:39:02 2021
Check interval: 0 (<none>)
Lifetime writes: 65 MB
Reserved blocks uid: 0 (user root)
Reserved blocks gid: 0 (group root)
First inode: 11
Inode size: 256
Required extra isize: 28
Desired extra isize: 28
Journal inode: 8
Default directory hash: half_md4
Directory Hash Seed: 6a94c4cb-b9e4-42fc-ab1d-384eea4da9ca
Journal backup: inode blocks
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
##1）创建物理卷
[root@centos8 ~]# 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 100G 0 part /
├─sda3 8:3 0 4G 0 part [SWAP]
├─sda4 8:4 0 1K 0 part
└─sda5 8:5 0 50G 0 part /data
sdb 8:16 0 20G 0 disk
└─sdb1 8:17 0 18G 0 part
sdc 8:32 0 2G 0 disk
sr0 11:0 1 7G 0 rom
[root@centos8 ~]# pvcreate /dev/sdb1 /dev/sdc
Physical volume "/dev/sdb1" successfully created.
Physical volume "/dev/sdc" successfully created.
[root@centos8 ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sdb1 lvm2 --- 18.00g 18.00g
/dev/sdc lvm2 --- 2.00g 2.00g
[root@centos8 ~]# pvdisplay
"/dev/sdb1" is a new physical volume of "18.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb1
VG Name
PV Size 18.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID mIlED9-di5O-3xmZ-PjnF-GiLB-0nIW-4SPc6e
"/dev/sdc" is a new physical volume of "2.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdc
VG Name
PV Size 2.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID b57Zqu-bo6B-Rcdw-rZtW-4iMr-xqjC-qnZ8k5
##创建卷组
[root@centos8 ~]# vgcreate -s 16M testvg /dev/sdb1 /dev/sdc
Volume group "testvg" successfully created
[root@centos8 ~]# vgs
VG #PV #LV #SN Attr VSize VFree
testvg 2 0 0 wz--n- <19.97g <19.97g
[root@centos8 ~]# vgdisplay
--- Volume group ---
VG Name testvg
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 1
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 0
Open LV 0
Max PV 0
Cur PV 2
Act PV 2
VG Size <19.97 GiB
PE Size 16.00 MiB
Total PE 1278
Alloc PE / Size 0 / 0
Free PE / Size 1278 / <19.97 GiB
VG UUID 9GcXDK-KxPq-Cinx-Tgqk-hjw3-wdiK-c8gzXz
##创建逻辑卷
[root@centos8 ~]# lvcreate -n testlv -L 5G testvg
WARNING: xfs signature detected on /dev/testvg/testlv at offset 0. Wipe it? [y/n]: y
Wiping xfs signature on /dev/testvg/testlv.
Logical volume "testlv" created.
[root@centos8 ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
testlv testvg -wi-a----- 5.00g
[root@centos8 ~]# lvdisplay
--- Logical volume ---
LV Path /dev/testvg/testlv
LV Name testlv
VG Name testvg
LV UUID 6IriL2-lsW1-CiNc-40yD-SFL6-sH3J-on6f6O
LV Write Access read/write
LV Creation host, time centos8.magedu.org, 2021-03-07 15:42:18 +0800
LV Status available
# open 0
LV Size 5.00 GiB
Current LE 320
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
##对逻辑卷创建文件系统
[root@centos8 ~]# ll /dev/testvg/testlv
lrwxrwxrwx. 1 root root 7 Mar 7 15:42 /dev/testvg/testlv -> ../dm-0
[root@centos8 ~]# mkfs.ext4 /dev/testvg/testlv
mke2fs 1.44.6 (5-Mar-2019)
Creating filesystem with 1310720 4k blocks and 327680 inodes
Filesystem UUID: 9062d0e8-3cab-473c-bca7-afc7b413145a
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
[root@centos8 ~]# blkid
...
/dev/mapper/testvg-testlv: UUID="9062d0e8-3cab-473c-bca7-afc7b413145a" TYPE="ext4"
##挂载
[root@centos8 ~]# vim /etc/fstab
[root@centos8 ~]# cat /etc/fstab
...
UUID=9062d0e8-3cab-473c-bca7-afc7b413145a /users ext4 defaults 0 0
[root@centos8 ~]# mkdir /users
[root@centos8 ~]# mount -a
[root@centos8 ~]# mount
...
/dev/mapper/testvg-testlv on /users type ext4 (rw,relatime,seclabel)
[root@centos8 ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
devtmpfs devtmpfs 967M 0 967M 0% /dev
tmpfs tmpfs 983M 0 983M 0% /dev/shm
tmpfs tmpfs 983M 8.7M 974M 1% /run
tmpfs tmpfs 983M 0 983M 0% /sys/fs/cgroup
/dev/sda2 xfs 100G 2.1G 98G 3% /
/dev/sda5 xfs 50G 390M 50G 1% /data
/dev/sda1 ext4 976M 112M 798M 13% /boot
tmpfs tmpfs 197M 0 197M 0% /run/user/0
/dev/mapper/testvg-testlv ext4 4.9G 20M 4.6G 1% /users
