CentOS的/boot分区空间不够用了，记录失败的扩容过程。
1. 背景
在“eBPF学习实践系列（二） – bcc tools网络工具集”里，实验tcpretrans时想用tc构造重传的场景。需要安装kernel-modules-extra，提示/boot空间不够了，之前装系统只分配了220M左右（Windows+CentOS8.5的双系统）。
于是准备进行扩容，虽然最终失败，但是熟练了操作，下一次装机能更快。。
2. 扩容过程
2.1. 扩容前情况
安装kernel-modules-extra，提示/boot空间不够了
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[root@anonymous ➜ /boot ]$ df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 16G 0 16G 0% /dev
tmpfs 16G 0 16G 0% /dev/shm
tmpfs 16G 17M 16G 1% /run
tmpfs 16G 0 16G 0% /sys/fs/cgroup
/dev/mapper/cl-root 85G 47G 39G 55% /
/dev/mapper/cl-home 64G 833M 64G 2% /home
/dev/nvme0n1p6 219M 210M 9.1M 96% /boot
/dev/nvme0n1p1 256M 39M 218M 15% /boot/efi
tmpfs 3.1G 0 3.1G 0% /run/user/0
lsblk查看分区和LVM情况
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[root@anonymous ➜ /var/crash ]$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
nvme0n1 259:0 0 477G 0 disk
|-nvme0n1p1 259:1 0 260M 0 part /boot/efi
|-nvme0n1p2 259:2 0 16M 0 part
|-nvme0n1p3 259:3 0 200G 0 part
|-nvme0n1p4 259:4 0 125.7G 0 part
|-nvme0n1p5 259:5 0 1000M 0 part
|-nvme0n1p6 259:6 0 224M 0 part /boot
`-nvme0n1p7 259:7 0 149.8G 0 part
|-cl-root 253:0 0 84.8G 0 lvm /
|-cl-swap 253:1 0 1G 0 lvm [SWAP]
`-cl-home 253:2 0 64G 0 lvm /home
fdisk 查看windows和CentOS双系统磁盘(一块512G固态硬盘)使用情况
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[root@anonymous ➜ /boot ]$ fdisk -l
Disk /dev/nvme0n1: 477 GiB, 512110190592 bytes, 1000215216 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: gpt
Disk identifier: B95E9484-333C-4235-8051-6D67EF703463
Device Start End Sectors Size Type
/dev/nvme0n1p1 2048 534527 532480 260M EFI System
/dev/nvme0n1p2 534528 567295 32768 16M Microsoft reserved
/dev/nvme0n1p3 567296 419997695 419430400 200G Microsoft basic data
/dev/nvme0n1p4 419997696 683593727 263596032 125.7G Microsoft basic data
/dev/nvme0n1p5 998166528 1000214527 2048000 1000M Windows recovery environment
/dev/nvme0n1p6 683593728 684052479 458752 224M Linux filesystem
/dev/nvme0n1p7 684052480 998166527 314114048 149.8G Linux LVM
2.2. 初步想法：/home保留60G，匀4G给/boot
备份数据并清理/home下的数据
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mkdir /home_bak
cp -rf /home/* /home_bak
rm -rf /home/*
umount /home
查看LVM的VG，没有空余空间了：Free PE / Size 0 / 0
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[root@anonymous ➜ / ]$ vgdisplay
--- Volume group ---
VG Name cl
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 2
Max PV 0
Cur PV 1
Act PV 1
VG Size <149.78 GiB
PE Size 4.00 MiB
Total PE 38343
Alloc PE / Size 38343 / <149.78 GiB
Free PE / Size 0 / 0
VG UUID MuH9jx-91dN-e5Yp-Wddi-vdXy-LCBZ-NrFi4b
查看各个逻辑卷LV
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[root@anonymous ➜ / ]$ lvdisplay
--- Logical volume ---
LV Path /dev/cl/swap
LV Name swap
VG Name cl
LV UUID GxDMFv-jqmV-kiY5-tpaw-dRuH-Jmbt-YQiN8k
LV Write Access read/write
LV Creation host, time desktop-mme7h3a, 2023-04-15 15:12:16 +0800
LV Status available
# open 2
LV Size 1.00 GiB
Current LE 256
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:1
--- Logical volume ---
LV Path /dev/cl/home
LV Name home
VG Name cl
LV UUID tA30Vo-M6f8-6Sma-vuXb-Ahxr-cwad-RQhxSd
LV Write Access read/write
LV Creation host, time desktop-mme7h3a, 2023-04-15 15:12:16 +0800
LV Status available
# open 0
LV Size 63.99 GiB
Current LE 16382
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
--- Logical volume ---
LV Path /dev/cl/root
LV Name root
VG Name cl
LV UUID k0MJa0-J1qH-5NTD-002y-PHDa-n0Px-LKa0I9
LV Write Access read/write
LV Creation host, time desktop-mme7h3a, 2023-04-15 15:12:17 +0800
LV Status available
# open 1
LV Size <84.79 GiB
Current LE 21705
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
删除/home对应的LV
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[root@anonymous ➜ / ]$ lvremove /dev/mapper/cl-home
Do you really want to remove active logical volume cl/home? [y/n]: y
Logical volume "home" successfully removed.
lvdisplay可以看到已经没有这个逻辑卷了
且VG里多了可用空间 Free PE / Size 16382 / 63.99 GiB
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[root@anonymous ➜ / ]$ vgdisplay
--- Volume group ---
VG Name cl
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 5
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 1
Act PV 1
VG Size <149.78 GiB
PE Size 4.00 MiB
Total PE 38343
Alloc PE / Size 21961 / <85.79 GiB
Free PE / Size 16382 / 63.99 GiB
VG UUID MuH9jx-91dN-e5Yp-Wddi-vdXy-LCBZ-NrFi4b
创建新的home逻辑卷：通过vgs查看卷组(VG)，并用lvcreate创建新的逻辑卷，空间用60G，预留3.99G
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[root@anonymous ➜ / ]$ vgs
VG #PV #LV #SN Attr VSize VFree
cl 1 2 0 wz--n- <149.78g 63.99g
[root@anonymous ➜ / ]$ lvcreate -L 60G -n home cl
WARNING: xfs signature detected on /dev/cl/home at offset 0. Wipe it? [y/n]: y
Wiping xfs signature on /dev/cl/home.
Logical volume "home" created.
可看到VG里可用只有3.99G了，且多了/dev/cl/home这个LV
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[root@anonymous ➜ / ]$ vgs
VG #PV #LV #SN Attr VSize VFree
cl 1 3 0 wz--n- <149.78g 3.99g
格式化LV，并挂载/home
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[root@anonymous ➜ / ]$ mkfs -t xfs /dev/mapper/cl-home
meta-data=/dev/mapper/cl-home isize=512 agcount=4, agsize=3932160 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=1, sparse=1, rmapbt=0
= reflink=1
data = bsize=4096 blocks=15728640, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0, ftype=1
log =internal log bsize=4096 blocks=7680, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
Discarding blocks...Done.
[root@anonymous ➜ / ]$
[root@anonymous ➜ / ]$ mount /dev/mapper/cl-home /home
可看到已经调整好/home的空间了，64G变成了60G。而后把数据还原回来。
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[root@anonymous ➜ / ]$ df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 16G 0 16G 0% /dev
tmpfs 16G 0 16G 0% /dev/shm
tmpfs 16G 17M 16G 1% /run
tmpfs 16G 0 16G 0% /sys/fs/cgroup
/dev/mapper/cl-root 85G 47G 39G 56% /
/dev/nvme0n1p6 219M 210M 9.1M 96% /boot
/dev/nvme0n1p1 256M 39M 218M 15% /boot/efi
tmpfs 3.1G 0 3.1G 0% /run/user/0
/dev/mapper/cl-home 60G 461M 60G 1% /home
[root@anonymous ➜ / ]$
[root@anonymous ➜ / ]$ mv /home_bak/* /home/
2.3. Oops! 匀不了
上面多的3.99G，想分配给/boot，这时才注意到不在同一个分区的LVM上。。。
来都来了，就分配给/吧，用lvextend分配剩下的3.99G给/对应的VG。
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[root@anonymous ➜ / ]$ lvextend -L +3.99G /dev/mapper/cl-root
Rounding size to boundary between physical extents: 3.99 GiB.
Size of logical volume cl/root changed from <84.79 GiB (21705 extents) to <88.78 GiB (22727 extents).
Logical volume cl/root successfully resized.
[root@anonymous ➜ / ]$
上面扩展了LV大小，文件系统是未感知到的。
几个LV分区都是xfs文件系统，用xfs_growfs扩展文件系统的空间，df -h查看/已经从85G变成89G了
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[root@desktop-mme7h3a ➜ /root ]$ cat /etc/fstab
/dev/mapper/cl-root / xfs defaults 0 0
UUID=e2dff41b-9fb8-4a28-bc72-e7505c5f291e /boot xfs defaults 0 0
UUID=FE38-DB70 /boot/efi vfat umask=0077,shortname=winnt 0 2
/dev/mapper/cl-home /home xfs defaults 0 0
/dev/mapper/cl-swap none swap defaults 0 0
[root@anonymous ➜ / ]$ xfs_growfs /
meta-data=/dev/mapper/cl-root isize=512 agcount=4, agsize=5556480 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=1, sparse=1, rmapbt=0
= reflink=1
data = bsize=4096 blocks=22225920, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0, ftype=1
log =internal log bsize=4096 blocks=10852, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 22225920 to 23272448
[root@anonymous ➜ / ]$
[root@anonymous ➜ / ]$ df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 16G 0 16G 0% /dev
tmpfs 16G 0 16G 0% /dev/shm
tmpfs 16G 17M 16G 1% /run
tmpfs 16G 0 16G 0% /sys/fs/cgroup
/dev/mapper/cl-root 89G 47G 43G 53% /
/dev/nvme0n1p6 219M 210M 9.1M 96% /boot
/dev/nvme0n1p1 256M 39M 218M 15% /boot/efi
tmpfs 3.1G 0 3.1G 0% /run/user/0
/dev/mapper/cl-home 60G 804M 60G 2% /home
参考：LVM—-从CentOS7默认安装的/home中转移空间到根目录/
虽然没成功，但上面的操作步骤实操了一把也不算白浪费。小结操作流程：
1、从lvm中某个lv释放空间给另一个lv
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# mkdir /backup
# mv /home/* /backup/
# umount /home
# lvremove /dev/centos/home
# lvcreate -L 50G -n home cents
# mkfs -t xfs /dev/centos/home
# mv /backup/* /home/
# lvextend -L +xxxG /dev/centos/root
# xfs_growfs root
# rm -rf /backup
2、新盘做LVM，思路—PV—-VG—LV
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lsblk
##创建PV
pvcreate /dev/sdb
##查看当前PV
pvscan 或者 pvs
##创建VG
vgcreate datevg /dev/sdb （datavg是起的VG名字）
##查看当前VG
vgscan
##加入新的PV到VG datevg
vgextend datevg /dev/sdc
#创建LV
lvcreate -L 200M -n lv1 datavg
(-L（指定lv的大小） 指定为200m lv1为起的LV名字 从datevg里创建)
## 查看LV
lvscan
/dev/datevg/lv1 200m
##格式化，创建文件系统挂载
mkfs.xfs /dev/datevg/lv1 或者 mkfs.ext4 /dev/datevg/lv1
mkdir /mnt/lv1
##临时挂载
mount /dev/datevg/lv1 /mnt/lv1
mount -a
df -h （df-Th） 加上TYPE 类型
LVM完成
2.4. Windows+CentOS双系统，从Windows匀一下
尝试从Windows上压缩空间分配给CentOS的 /boot (这部分空间是单独分区的，没有在LVM里)
问GPT：
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Q：假设你是linux系统专家，磁盘方面特别熟悉
Q：ssd上分了两个分区A和B，其中分区A建了lvm，怎么把lvm剩余的空间分配给B
备份数据->缩小LVM逻辑卷->删除LVM卷组->重新分区
但是查了下xfs无法缩小卷
Q：lvreduce无法对xfs缩容吗
lvreduce确实无法直接对XFS文件系统缩容。受限于XFS文件系统特性
balabala...
Q：ssd上有windows和centos双系统，怎么从windows的分区分配空间给linux的分区
备份数据->在Windows下缩小分区->在Linux下扩展分区
开始操作：
重启进入windows -> “此电脑”右键管理，进入”磁盘管理” -> 压缩磁盘，空4G出来
重启进入linux，新压缩的空间呢？被GPT坑了! 压缩出来的空间还需要格式化成NTFS格式！(创建新卷格式化)
重启进入linux，可以看到4G空间了(nvme0n1p4)
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[root@desktop-mme7h3a ➜ /root ]$ fdisk -l
...
Device Start End Sectors Size Type
/dev/nvme0n1p1 2048 534527 532480 260M EFI System
/dev/nvme0n1p2 534528 567295 32768 16M Microsoft reserved
/dev/nvme0n1p3 567296 411609087 411041792 196G Microsoft basic data
/dev/nvme0n1p4 411609088 419995647 8386560 4G Microsoft basic data
/dev/nvme0n1p5 419997696 683593727 263596032 125.7G Microsoft basic data
/dev/nvme0n1p6 683593728 684052479 458752 224M Linux filesystem
/dev/nvme0n1p7 684052480 998166527 314114048 149.8G Linux LVM
/dev/nvme0n1p8 998166528 1000214527 2048000 1000M Windows recovery environment
lsblk也能看到：
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[root@desktop-mme7h3a ➜ /root ]$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
nvme0n1 259:0 0 477G 0 disk
|-nvme0n1p1 259:1 0 260M 0 part /boot/efi
|-nvme0n1p2 259:2 0 16M 0 part
|-nvme0n1p3 259:3 0 196G 0 part
|-nvme0n1p4 259:4 0 4G 0 part
|-nvme0n1p5 259:5 0 125.7G 0 part
|-nvme0n1p6 259:6 0 224M 0 part
|-nvme0n1p7 259:7 0 149.8G 0 part
| |-cl-root 253:0 0 88.8G 0 lvm /
| |-cl-swap 253:1 0 1G 0 lvm [SWAP]
| `-cl-home 253:2 0 60G 0 lvm /home
`-nvme0n1p8 259:8 0 1000M 0 part
格式化：mkfs.xfs -f /dev/nvme0n1p4
备份/boot数据，关闭挂载，重启系统
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/dev/mapper/cl-root / xfs defaults 0 0
#UUID=e2dff41b-9fb8-4a28-bc72-e7505c5f291e /boot xfs defaults 0 0
UUID=FE38-DB70 /boot/efi vfat umask=0077,shortname=winnt 0 2
/dev/mapper/cl-home /home xfs defaults 0 0
/dev/mapper/cl-swap none swap defaults 0 0
删除4G分区和原来的/boot分区(224M，按提示的分区号来，此处分别为4和6)
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[root@desktop-mme7h3a ➜ /root ]$ fdisk /dev/nvme0n1
Command (m for help): p
Device Start End Sectors Size Type
/dev/nvme0n1p1 2048 534527 532480 260M EFI System
/dev/nvme0n1p2 534528 567295 32768 16M Microsoft reserved
/dev/nvme0n1p3 567296 411609087 411041792 196G Microsoft basic data
/dev/nvme0n1p4 411609088 419995647 8386560 4G Microsoft basic data
/dev/nvme0n1p5 419997696 683593727 263596032 125.7G Microsoft basic data
/dev/nvme0n1p6 683593728 684052479 458752 224M Linux filesystem
/dev/nvme0n1p7 684052480 998166527 314114048 149.8G Linux LVM
/dev/nvme0n1p8 998166528 1000214527 2048000 1000M Windows recovery environment
# 删除分区
Command (m for help): d
Partition number (1-8, default 8): 4
Partition 4 has been deleted.
Command (m for help): p
# 可看到结果里已经没有4G的分区了，略
# 查看空余
Command (m for help): F
Unpartitioned space /dev/nvme0n1: 4 GiB, 4294967296 bytes, 8388608 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
Start End Sectors Size
411609088 419997695 8388608 4G
# 删除分区
Command (m for help): d
Partition number (1-3,5-8, default 8): 6
Partition 6 has been deleted.
# 保存退出
Command (m for help): w
The partition table has been altered.
Syncing disks.
创建新分区：
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...
# 创建新分区
Command (m for help): n
Partition number (4,6,9-128, default 4): 6
First sector (411609088-1000215182, default 411609088):
Last sector, +sectors or +size{K,M,G,T,P} (411609088-419997695, default 419997695):
Created a new partition 6 of type 'Linux filesystem' and of size 4 GiB.
Partition #6 contains a xfs signature.
# 输y确认
Do you want to remove the signature? [Y]es/[N]o: y
The signature will be removed by a write command.
# 保存退出
Command (m for help): w
The partition table has been altered.
Syncing disks.
格式化mkfs.xfs -f /dev/nvme0n1p6，并查看lsblk
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[root@desktop-mme7h3a ➜ /root ]$ lsblk -f
NAME FSTYPE LABEL UUID MOUNTPOINT
nvme0n1
|-nvme0n1p1 vfat SYSTEM FE38-DB70 /boot/efi
|-nvme0n1p2
|-nvme0n1p3 ntfs Windows 2CAC3C7BAC3C419E
|-nvme0n1p5 ntfs DATA1 1C823E3E823E1D28
|-nvme0n1p6 xfs e2dff41b-9fb8-4a28-bc72-e7505c5f291e
|-nvme0n1p7 LVM2_member PfPJxg-ZFLM-YSWj-hEr1-x7Mb-vpii-nlonSB
| |-cl-root xfs 564672f7-d5a7-424b-b6a0-5e265113b7d5 /
| |-cl-swap swap ca68fa0f-de7e-4645-8afa-5592011d5617 [SWAP]
| `-cl-home xfs f69bf04d-529f-47bc-a5aa-7dbce29d8825 /home
`-nvme0n1p8 ntfs WinRE_DRV 5A783F01783EDB87
挂载/boot到新分区，还原数据，设置/etc/fstab自动挂载
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[root@desktop-mme7h3a ➜ /root ]$ mount /dev/nvme0n1p6 /boot
[root@desktop-mme7h3a ➜ /root ]$ df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 16G 0 16G 0% /dev
tmpfs 16G 0 16G 0% /dev/shm
tmpfs 16G 17M 16G 1% /run
tmpfs 16G 0 16G 0% /sys/fs/cgroup
/dev/mapper/cl-root 89G 47G 43G 53% /
/dev/mapper/cl-home 60G 804M 60G 2% /home
tmpfs 3.1G 0 3.1G 0% /run/user/0
/dev/nvme0n1p6 4.0G 61M 4.0G 2% /boot
[root@desktop-mme7h3a ➜ /root ]$ cp -rf /home/boot_bak/* /boot
[root@desktop-mme7h3a ➜ /root ]
[root@desktop-mme7h3a ➜ /root ]$ vi /etc/fstab
[root@desktop-mme7h3a ➜ /root ]
重启系统，卧豁没起来。。。 (要去上班了，晚上继续)
3. 重装Linux系统
晚上下班回来，看PC已经找不到启动项了，先不折腾了。上次Rufus做的系统U盘还在，重新装CentOS系统。
进Windows把连续的卷空间还原回去(感觉之前不应该从C盘压缩空间，不连续)，删除掉CentOS的几个卷。
半小时左右装完（/boot这次直接设置4G）。
1、设置免密登录 ssh-copy-id -i ~/.ssh/id_rsa.pub root@192.168.1.150
2、修改yum源为阿里云
/etc/yum.repos.d/下配置都移走
curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-8.repo
上面的yum源，下载的内核版本是4.18.0-348.7.1.el8_5.x86_64，而系统实际是4.18.0-348.el8.x86_64，小版本不一样，修改为下述源（下面看貌似结果还是一样）
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[root@desktop-mme7h3a ➜ /root ]$ cat /etc/system-release
CentOS Linux release 8.5.2111
[root@desktop-mme7h3a ➜ /root ]wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-vault-8.5.2111.repo
yum clean all; yum makecache
3、安装oh-my-zsh、vim插件
4. 安装kernel-modules-extra
回归原始需求，把tc依赖的kernel-modules-extra装起来，看有91M左右
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[root@desktop-mme7h3a ➜ /root ]$ yum install kernel-modules-extra
Failed to set locale, defaulting to C.UTF-8
Last metadata expiration check: 0:00:27 ago on Wed Jun 12 23:19:41 2024.
Dependencies resolved.
===============================================================================================
Package Architecture Version Repository Size
===============================================================================================
Installing:
kernel-core x86_64 4.18.0-348.7.1.el8_5 base 38 M
kernel-modules x86_64 4.18.0-348.7.1.el8_5 base 30 M
kernel-modules-extra x86_64 4.18.0-348.7.1.el8_5 base 7.6 M
Transaction Summary
===============================================================================================
Install 3 Packages
Total download size: 75 M
Installed size: 91 M
Is this ok [y/N]:
小版本还是不对应，系统内核为：4.18.0-348.el8.x86_64，但是上面是4.18.0-348.7.1.el8_5。找了一圈yum源只有这个版本内核了。
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[root@desktop-mme7h3a ➜ /etc/yum.repos.d ]$ uname -a
Linux desktop-mme7h3a 4.18.0-348.el8.x86_64 #1 SMP Tue Oct 19 15:14:17 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
默认内核调整成新装的版本，刚刚yum安装时好像自动就设置了，重启系统，看内核已经是新版本了。
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[root@desktop-mme7h3a ➜ /root ]$ uname -a
Linux desktop-mme7h3a 4.18.0-348.7.1.el8_5.x86_64 #1 SMP Wed Dec 22 13:25:12 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
加载内核模块：sch_netem，加载成功。使用tc模拟丢包，成功
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[root@desktop-mme7h3a ➜ /root ]$ modprobe sch_netem
[root@desktop-mme7h3a ➜ /root ]$
[root@desktop-mme7h3a ➜ /root ]$ tc qdisc add dev enp4s0 root netem loss 10%
[root@desktop-mme7h3a ➜ /root ]$ tc qdisc show
qdisc noqueue 0: dev lo root refcnt 2
qdisc netem 8002: dev enp4s0 root refcnt 2 limit 1000 loss 10%
[root@desktop-mme7h3a ➜ /root ]$ tc qdisc change dev enp4s0 root netem loss 20%
[root@desktop-mme7h3a ➜ /root ]$ tc qdisc show
5. 小结
折腾了一下LVM操作，又重新装了一次机。
6. 参考
1、LVM—-从CentOS7默认安装的/home中转移空间到根目录/
2、GPT
