linux-centos7-disk partitioning system grub common fault row

Grub Troubleshooting General Troubleshooting
MBR446 byte overwrite cannot start

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The above command is equivalent to corrupting the MBR446 byte dd overlay
disc boot required after reboot
Select First Aid mode
You only need to enter
GRUB2-INSTALL/DEV/SDA
Reboot is OK.
Example 2:grub.cfg kernel configuration file corruption removal
Delete all files directly under/boot/grub2/
rm-rf/boot/grub2/*
or CD-ROM boot , into rescue mode
The workaround is to reinstall the kernel files , because Linux is basically completely open source, so the basic any file problems can be fixed,
RPM-IVH/**/kernel-*** kernel file--force
must be forced to overwrite , because the original has installed the kernel package, do not force the installation can not continue, using Yum need to uninstall after installation, no RPM convenient
---------------------------------------------------------------------------------------------Disk Partitions

MBR format up to 4 primary partitions, and then establish logical partitions, each with a maximum on-line 2T MBR with only 64 partition tables, each partition needs 16 bytes to represent so 4 partitions
GPT format up to 128 partitions, partition size varies by system, maximum support 18EB[1EB=1024PB 1PB=1024TB] Partition table has redundancy .
fdisk is common and normal. The most common partitioning method
Gdisk can partition GPT format partition usage is basically the same as Fdisk
parted is more flexible than before, free to set MBR GPT format
mklabel msdos[mbr format] gpt[gpt format]
Primary primary partition extended extended partition logical logical partition
 Set number flag State is used to set the purpose of the partition,Flag:Boot,LVM,raid. SThe Tate:on/off means to turn on or off.

parted tool does not need to be saved after sorting out the area, enterQyou can exit.
Vim/etc/fstab automatic mount partition normal partition way with UUID hanging most suitable
xfs_admin-u viewing UUID
-----------------------------------------------------------------Swap extension
Create swap blocks in the space you need
DD If=/dev/zero of=/swapfile bs=1m count=2048
Creating Blocks
mkswap/swapfile format is swap
chmod 600/swapfile Permissions
swapon/swapfile Start
Cat/proc/swaps to see if the swap was successfully added
-------------------------------------------------------LVM Volumes
pvcreate/dev/sdb[123 ABC] multi-select multi-match multiple creation of the supporting PV
Pvscan View PV
vgcreate name/dev/sdb[123 ABC] is already a group of PV added cities
Vgscan Group View
lvcreate-l size [100M]-n name Group name create partition
Lvscan View the partition.
mkfs-t XFS Device name partition formatted partition
mounts to use the !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

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linux-centos7-disk partitioning system grub common fault row