Linux碎片知识与问题拾遗
1. Fedora扩容磁盘
Fedora虚拟机在创建的时候明明分配了40G，但是OS中看到的却只有20G，直到空间不够用了才发现，如下对扩容做个记录，以便后续查阅。
1.1 查看可用空间
[root@localhost .cache]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/fedora_192-root 15G 11G 4.2G 73% /
devtmpfs 4.0M 0 4.0M 0% /dev
tmpfs 2.0G 0 2.0G 0% /dev/shm
efivarfs 256K 32K 225K 13% /sys/firmware/efi/efivars
tmpfs 780M 1.3M 779M 1% /run
tmpfs 2.0G 4.0K 2.0G 1% /tmp
/dev/nvme0n1p2 960M 244M 717M 26% /boot
/dev/nvme0n1p1 599M 11M 588M 2% /boot/efi
tmpfs 390M 12K 390M 1% /run/user/0
[root@localhost .cache]#
[root@localhost .cache]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
root fedora_192 -wi-ao---- 15.00g
[root@localhost .cache]#
# pvs查看还有23.41g可以分配
[root@localhost .cache]# pvs
PV VG Fmt Attr PSize PFree
/dev/nvme0n1p3 fedora_192 lvm2 a-- 38.41g 23.41g
[root@localhost .cache]#
1.2. pv扩容
# 可用空间全部分配给root
[root@localhost .cache]# lvextend -L+23.41g /dev/mapper/fedora_192-root
Rounding size to boundary between physical extents: 23.41 GiB.
Size of logical volume fedora_192/root changed from 15.00 GiB (3840 extents) to 38.41 GiB (9833 extents).
Logical volume fedora_192/root successfully resized.
[root@localhost .cache]# pvs
PV VG Fmt Attr PSize PFree
/dev/nvme0n1p3 fedora_192 lvm2 a-- 38.41g 0
[root@localhost .cache]#
# 此时文件系统还是原来的大小
[root@localhost .cache]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/fedora_192-root 15G 11G 4.2G 73% /
devtmpfs 4.0M 0 4.0M 0% /dev
tmpfs 2.0G 0 2.0G 0% /dev/shm
efivarfs 256K 32K 225K 13% /sys/firmware/efi/efivars
tmpfs 780M 1.3M 779M 1% /run
tmpfs 2.0G 4.0K 2.0G 1% /tmp
/dev/nvme0n1p2 960M 244M 717M 26% /boot
/dev/nvme0n1p1 599M 11M 588M 2% /boot/efi
tmpfs 390M 12K 390M 1% /run/user/0
[root@localhost .cache]#
1.3. xfs容
[root@localhost .cache]# xfs_growfs /dev/mapper/fedora_192-root
meta-data=/dev/mapper/fedora_192-root isize=512 agcount=4, agsize=983040 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=1, sparse=1, rmapbt=0
= reflink=1 bigtime=1 inobtcount=1 nrext64=0
data = bsize=4096 blocks=3932160, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0, ftype=1
log =internal log bsize=4096 blocks=16384, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 3932160 to 10068992
[root@localhost .cache]#
# 此时文件系统完成扩容
[root@localhost .cache]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/fedora_192-root 39G 11G 28G 29% /
devtmpfs 4.0M 0 4.0M 0% /dev
tmpfs 2.0G 0 2.0G 0% /dev/shm
efivarfs 256K 32K 225K 13% /sys/firmware/efi/efivars
tmpfs 780M 1.3M 779M 1% /run
tmpfs 2.0G 4.0K 2.0G 1% /tmp
/dev/nvme0n1p2 960M 244M 717M 26% /boot
/dev/nvme0n1p1 599M 11M 588M 2% /boot/efi
tmpfs 390M 12K 390M 1% /run/user/0
[root@localhost .cache]#
2. NTP Server数量
NTP Server应该配置几台？
答：至少配置4台NTP Server，详情如下。
2.1 Using Enough Time Sources
An NTP implementation that is compliant with RFC5905 takes the available sources of time and submits this timing data to sophisticated intersection, clustering, and combining algorithms to get the best estimate of the correct time. The description of these algorithms is beyond the scope of this document. Interested readers should read RFC5905 or the detailed description of NTP in [MILLS2006].
If there is only one source of time, the answer is obvious. It may not be a good source of time, but it's the only source that can be considered. Any issue with the time at the source will be passed on to the client.
If there are two sources of time and they align well enough, then the best time can be calculated easily. But if one source fails, then the solution degrades to the single-source solution outlined above. And if the two sources don't agree, it will be difficult to know which one is correct without making use of information from outside of the protocol.
If there are three sources of time, there is more data available to converge on the best calculated time, and this time is more likely to be accurate. And the loss of one of the sources (by becoming unreachable or unusable) can be tolerated. But at that point, the solution degrades to the two-source solution.
Having four or more sources of time is better as long as the sources are diverse (Section 3.3). If one of these sources develops a problem, there are still at least three other time sources.
This analysis assumes that a majority of the servers used in the solution are honest, even if some may be inaccurate. Operators should be aware of the possibility that if an attacker is in control of the network, the time coming from all servers could be compromised.
Operators who are concerned with maintaining accurate time SHOULD use at least four independent, diverse sources of time. Four sources will provide sufficient backup in case one source goes down. If four sources are not available, operators MAY use fewer sources, which is subject to the risks outlined above.
Operators are advised to monitor all time sources that are in use. If time sources do not generally align, operators are encouraged to investigate the cause and either correct the problems or stop using defective servers.
2.2 参考
3. 获取RedHat内核源码
下载内核源码学习及排查问题。
3.1 RHEL/Centos 7.9 kernel source code
在CentOS Vault Mirror下载对应的版本。
# 下载
wget https://vault.centos.org/7.9.2009/updates/Source/SPackages/kernel-3.10.0-1160.108.1.el7.src.rpm
# 提取rpm包文件
rpm2cpio ./kernel-3.10.0-1160.108.1.el7.src.rpm | cpio -idmv --directory ./kernel-3.10.0-1160
kernel-3.10.0-1160/目录下会生成linux-3.10.0-1160.108.1.el7.tar.xz ，移动到指定位置解压即可。
tar xf linux-3.10.0-1160.108.1.el7.tar.xz
mv linux-3.10.0-1160.108.1.el7 linux-3.10.0-1160
cd linux-3.10.0-1160/
rm -f configs
3.2 RHEL 8.8 kernel source code
在Red Hat Packages搜索并下载。
比如以kernel-4.18.0-477.27.1.el8_8.src.rpm关键字搜索，点击查询结果会中转到如下页面，也可以在这个页面选择搜索。
https://access.redhat.com/downloads/content/kernel/4.18.0-477.27.1.el8_8/x86_64/fd431d51/package
内核源码文件提取与7.9一致。
4. Introduction to eBPF in Red Hat Enterprise Linux 7
5. Ubuntu 22.04 扩容磁盘
5.1 VMware Fusion扩容磁盘
在关机状态下扩容。
5.2 在Ubuntu中确认磁盘信息
root@localhost:~# fdisk -l
Disk /dev/loop0: 77.38 MiB, 81137664 bytes, 158472 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 /dev/loop1: 59.75 MiB, 62652416 bytes, 122368 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 /dev/loop2: 59.77 MiB, 62676992 bytes, 122416 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 /dev/loop3: 77.38 MiB, 81133568 bytes, 158464 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 /dev/loop4: 33.65 MiB, 35287040 bytes, 68920 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 /dev/loop5: 33.71 MiB, 35344384 bytes, 69032 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
GPT PMBR size mismatch (167772159 != 251658239) will be corrected by write.
Disk /dev/nvme0n1: 120 GiB, 128849018880 bytes, 251658240 sectors # 和VMware分配的磁盘大小一致
Disk model: VMware Virtual NVMe Disk
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: 93D81391-7E1D-4563-ACEB-B42E291C647B
Device Start End Sectors Size Type
/dev/nvme0n1p1 2048 2203647 2201600 1G EFI System
/dev/nvme0n1p2 2203648 6397951 4194304 2G Linux filesystem
/dev/nvme0n1p3 6397952 167770111 161372160 76.9G Linux filesystem
Disk /dev/mapper/ubuntu--vg-ubuntu--lv: 76.95 GiB, 82619400192 bytes, 161366016 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
root@localhost:~#
5.3 扩容分区
root@localhost:~# fdisk /dev/nvme0n1
Welcome to fdisk (util-linux 2.37.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
GPT PMBR size mismatch (167772159 != 251658239) will be corrected by write.
This disk is currently in use - repartitioning is probably a bad idea.
It's recommended to umount all file systems, and swapoff all swap
partitions on this disk.
Command (m for help): m # help
Help:
GPT
M enter protective/hybrid MBR
Generic
d delete a partition
F list free unpartitioned space
l list known partition types
n add a new partition
p print the partition table
t change a partition type
v verify the partition table
i print information about a partition
Misc
m print this menu
x extra functionality (experts only)
Script
I load disk layout from sfdisk script file
O dump disk layout to sfdisk script file
Save & Exit
w write table to disk and exit
q quit without saving changes
Create a new label
g create a new empty GPT partition table
G create a new empty SGI (IRIX) partition table
o create a new empty DOS partition table
s create a new empty Sun partition table
Command (m for help): n # 增加分区
Partition number (4-128, default 4): # 回车
First sector (167770112-251658206, default 167770112): # 回车
Last sector, +/-sectors or +/-size{K,M,G,T,P} (167770112-251658206, default 251658206): # 回车
Created a new partition 4 of type 'Linux filesystem' and of size 40 GiB.
Command (m for help): w # 写入分区表
he partition table has been altered.
Syncing disks.
root@localhost:~#
验证已经增加了新分区。
root@localhost:~# fdisk -l
Disk /dev/loop0: 77.38 MiB, 81137664 bytes, 158472 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 /dev/loop1: 59.75 MiB, 62652416 bytes, 122368 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 /dev/loop2: 59.77 MiB, 62676992 bytes, 122416 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 /dev/loop3: 77.38 MiB, 81133568 bytes, 158464 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 /dev/loop4: 33.65 MiB, 35287040 bytes, 68920 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 /dev/loop5: 33.71 MiB, 35344384 bytes, 69032 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 /dev/nvme0n1: 120 GiB, 128849018880 bytes, 251658240 sectors
Disk model: VMware Virtual NVMe Disk
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: 93D81391-7E1D-4563-ACEB-B42E291C647B
Device Start End Sectors Size Type
/dev/nvme0n1p1 2048 2203647 2201600 1G EFI System
/dev/nvme0n1p2 2203648 6397951 4194304 2G Linux filesystem
/dev/nvme0n1p3 6397952 167770111 161372160 76.9G Linux filesystem
/dev/nvme0n1p4 167770112 251658206 83888095 40G Linux filesystem # 新增分区
Disk /dev/mapper/ubuntu--vg-ubuntu--lv: 76.95 GiB, 82619400192 bytes, 161366016 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
root@localhost:~#
5.4 扩容PV
root@localhost:~# pvcreate /dev/nvme0n1p4
Physical volume "/dev/nvme0n1p4" successfully created.
root@localhost:~#
root@localhost:~# vgdisplay
--- Volume group ---
VG Name ubuntu-vg
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 2
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 1
Max PV 0
Cur PV 1
Act PV 1
VG Size <76.95 GiB
PE Size 4.00 MiB
Total PE 19698
Alloc PE / Size 19698 / <76.95 GiB
Free PE / Size 0 / 0 # vg可用空间为0
VG UUID DBHQfM-Vs4z-N3ns-dWTL-zowt-FW3J-sZb34I
root@localhost:~#
5.5 扩容VG
root@localhost:~# vgextend ubuntu-vg /dev/nvme0n1p4
Volume group "ubuntu-vg" successfully extended
root@localhost:~#
root@localhost:~#
root@localhost:~# vgdisplay
--- Volume group ---
VG Name ubuntu-vg
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 3
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 1
Max PV 0
Cur PV 2
Act PV 2
VG Size 116.94 GiB
PE Size 4.00 MiB
Total PE 29937
Alloc PE / Size 19698 / <76.95 GiB
Free PE / Size 10239 / <40.00 GiB # 可以看到已经扩容成功，vg可用空间为40G
VG UUID DBHQfM-Vs4z-N3ns-dWTL-zowt-FW3J-sZb34I
root@localhost:~#
5.6 扩容LV
这里使用百分比扩容，将可用空间都分配给LV。
root@localhost:~# lvextend -l +100%FREE /dev/ubuntu-vg/ubuntu-lv
Size of logical volume ubuntu-vg/ubuntu-lv changed from <76.95 GiB (19698 extents) to 116.94 GiB (29937 extents).
Logical volume ubuntu-vg/ubuntu-lv successfully resized.
root@localhost:~#
5.7 扩容文件系统
这里要根据具体文件系统判断要使用的命令，此处是ext4 ，使用resize2fs。
完成后关机，创建快照，再开机使用。
root@localhost:~# lsblk -f
NAME FSTYPE FSVER LABEL UUID FSAVAIL FSUSE% MOUNTPOINTS
loop0 squashfs 4.0 0 100% /snap/lxd/29353
loop1 squashfs 4.0 0 100% /snap/core20/2321
loop2 squashfs 4.0 0 100% /snap/core20/2383
loop3 squashfs 4.0 0 100% /snap/lxd/28384
loop4 squashfs 4.0 0 100% /snap/snapd/21467
loop5 squashfs 4.0 0 100% /snap/snapd/21761
sr0
nvme0n1
├─nvme0n1p1 vfat FAT32 2915-B99F 1G 1% /boot/efi
├─nvme0n1p2 ext4 1.0 01925585-9548-413b-a539-e3412871af3c 1.5G 13% /boot
├─nvme0n1p3 LVM2_member LVM2 001 Pafs9G-NZ5j-iLsy-ZsTv-EZL0-oOQ2-JUSMbD
│ └─ubuntu--vg-ubuntu--lv ext4 1.0 c8df5b7d-874e-45bf-9283-ad063d01fc9e 22.5G 65% /
└─nvme0n1p4 LVM2_member LVM2 001 3HDZfU-xATg-VK13-2GwI-1EjP-gLOy-qtV3Ba
└─ubuntu--vg-ubuntu--lv ext4 1.0 c8df5b7d-874e-45bf-9283-ad063d01fc9e 22.5G 65% /
root@localhost:~#
root@localhost:~#
root@localhost:~# resize2fs /dev/ubuntu-vg/ubuntu-lv # 扩容文件系统
resize2fs 1.46.5 (30-Dec-2021)
Filesystem at /dev/ubuntu-vg/ubuntu-lv is mounted on /; on-line resizing required
old_desc_blocks = 10, new_desc_blocks = 15
The filesystem on /dev/ubuntu-vg/ubuntu-lv is now 30655488 (4k) blocks long.
root@localhost:~# df -h
Filesystem Size Used Avail Use% Mounted on
tmpfs 1.6G 1.3M 1.6G 1% /run
/dev/mapper/ubuntu--vg-ubuntu--lv 115G 49G 61G 45% / # 此处看到已经扩容成功
tmpfs 7.8G 0 7.8G 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
/dev/nvme0n1p2 2.0G 251M 1.6G 14% /boot
/dev/nvme0n1p1 1.1G 6.4M 1.1G 1% /boot/efi
tmpfs 1.6G 4.0K 1.6G 1% /run/user/1000
root@localhost:~# sync
root@localhost:~# df -h
Filesystem Size Used Avail Use% Mounted on
tmpfs 1.6G 1.3M 1.6G 1% /run
/dev/mapper/ubuntu--vg-ubuntu--lv 115G 49G 61G 45% /
tmpfs 7.8G 0 7.8G 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
/dev/nvme0n1p2 2.0G 251M 1.6G 14% /boot
/dev/nvme0n1p1 1.1G 6.4M 1.1G 1% /boot/efi
tmpfs 1.6G 4.0K 1.6G 1% /run/user/1000
root@localhost:~# exit
logout
kangxiaoning@localhost:~$
Last modified: 27 October 2024