ext4文件系统可以经行扩缩容操作，但xfs的文件系统只能扩容，无法缩容
所以如果需要进行xfs的缩容，可以先使用xfsdump备份文件系统，然后对逻辑卷(/分区)进行缩容操作（此时原xfs文件系统会损坏），然后再重新格式化该逻辑卷(/分区)，最后xfsrestore将备份还原到该逻辑卷(/分区)
当然，这需要先下载xfsdump工具
[root@localhost ~]# df -Th #查看文件系统磁盘使用情况
Filesystem Type Size Used Avail Use% Mounted on
devtmpfs devtmpfs 7.9G 0 7.9G 0% /dev
tmpfs tmpfs 7.9G 0 7.9G 0% /dev/shm
tmpfs tmpfs 7.9G 8.9M 7.9G 1% /run
tmpfs tmpfs 7.9G 0 7.9G 0% /sys/fs/cgroup
/dev/mapper/centos-root xfs 50G 3.0G 47G 6% /
/dev/sda2 xfs 1014M 131M 884M 13% /boot
/dev/sda1 vfat 200M 12M 189M 6% /boot/efi
/dev/mapper/centos-home xfs 64G 33M 64G 1% /home
tmpfs tmpfs 1.6G 0 1.6G 0% /run/user/0
[root@localhost ~]# xfsdump -f ~/home.xfs_dump /home #备份文件系统
xfsdump: using file dump (drive_simple) strategy
xfsdump: version 3.1.7 (dump format 3.0) - type ^C for status and control ============================= dump label dialog ============================== please enter label for this dump session (timeout in 300 sec)
-> #自定义备份会话标签，可直接回车
session label entered: "" --------------------------------- end dialog --------------------------------- xfsdump: WARNING: no session label specified
xfsdump: level 0 dump of localhost.localdomain:/home
xfsdump: dump date: Wed Oct 26 22:48:12 2022
xfsdump: session id: e3f11041-db93-41db-954f-b1101edb7b42
xfsdump: session label: ""
xfsdump: ino map phase 1: constructing initial dump list
xfsdump: ino map phase 2: skipping (no pruning necessary)
xfsdump: ino map phase 3: skipping (only one dump stream)
xfsdump: ino map construction complete
xfsdump: estimated dump size: 20800 bytes ============================= media label dialog ============================= please enter label for media in drive 0 (timeout in 300 sec)
-> #自定义备份媒体标签，可直接回车
media label entered: "" --------------------------------- end dialog --------------------------------- xfsdump: WARNING: no media label specified
xfsdump: creating dump session media file 0 (media 0, file 0)
xfsdump: dumping ino map
xfsdump: dumping directories
xfsdump: dumping non-directory files
xfsdump: ending media file
xfsdump: media file size 21352 bytes
xfsdump: dump size (non-dir files) : 0 bytes
xfsdump: dump complete: 1 seconds elapsed
xfsdump: Dump Summary:
xfsdump: stream 0 /root/home.xfs_dump OK (success)
xfsdump: Dump Status: SUCCESS
[root@localhost ~]# umount /home #卸载home分区，（业内习惯性叫home分区，其实就是home逻辑卷）
[root@localhost ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
home centos -wi-a----- 64.00g
root centos -wi-ao---- 50.00g
swap centos -wi-ao---- 12.80g
[root@localhost ~]# vgs
VG #PV #LV #SN Attr VSize VFree
centos 1 3 0 wz--n- 126.80g 0
[root@localhost ~]# lvreduce -L 24G /dev/mapper/centos-home #home分区缩容
WARNING: Reducing active logical volume to 24.00 GiB.
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce centos/home? [y/n]: y
Size of logical volume centos/home changed from 64.00 GiB (16384 extents) to 24.00 GiB (6144 extents).
Logical volume centos/home successfully resized.
[root@localhost ~]# lvextend -l +100%FREE /dev/mapper/centos-root #将空余空间全部给root分区
Size of logical volume centos/root changed from 50.00 GiB (12800 extents) to 90.00 GiB (23040 extents).
Logical volume centos/root successfully resized.
[root@localhost ~]# xfs_growfs /dev/mapper/centos-root #逻辑卷扩容后，需要刷新文件系统
meta-data=/dev/mapper/centos-root isize=512 agcount=4, agsize=3276800 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=13107200, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal bsize=4096 blocks=6400, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 13107200 to 23592960
[root@localhost ~]# df -Th
Filesystem Type Size Used Avail Use% Mounted on
devtmpfs devtmpfs 7.9G 0 7.9G 0% /dev
tmpfs tmpfs 7.9G 0 7.9G 0% /dev/shm
tmpfs tmpfs 7.9G 8.9M 7.9G 1% /run
tmpfs tmpfs 7.9G 0 7.9G 0% /sys/fs/cgroup
/dev/mapper/centos-root xfs 90G 3.0G 87G 4% /
/dev/sda2 xfs 1014M 131M 884M 13% /boot
/dev/sda1 vfat 200M 12M 189M 6% /boot/efi
tmpfs tmpfs 1.6G 0 1.6G 0% /run/user/0
[root@localhost ~]# mkfs.xfs /dev/mapper/centos-home -f #格式化home分区
meta-data=/dev/mapper/centos-home isize=512 agcount=4, agsize=1572864 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=6291456, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=3072, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@localhost ~]# mount /dev/mapper/centos-home /home/ #重新挂载home分区
[root@localhost ~]# xfsrestore -f ~/home.xfs_dump /home #home文件系统还原
xfsrestore: using file dump (drive_simple) strategy
xfsrestore: version 3.1.7 (dump format 3.0) - type ^C for status and control
xfsrestore: searching media for dump
xfsrestore: examining media file 0
xfsrestore: dump description:
xfsrestore: hostname: localhost.localdomain
xfsrestore: mount point: /home
xfsrestore: volume: /dev/mapper/centos-home
xfsrestore: session time: Wed Oct 26 22:48:12 2022
xfsrestore: level: 0
xfsrestore: session label: ""
xfsrestore: media label: ""
xfsrestore: file system id: e59981eb-07f9-44e4-9c6f-9ecd8afc8b81
xfsrestore: session id: e3f11041-db93-41db-954f-b1101edb7b42
xfsrestore: media id: fd63d3e5-9bee-49f8-9872-9d17e82f80fc
xfsrestore: using online session inventory
xfsrestore: searching media for directory dump
xfsrestore: reading directories
xfsrestore: 1 directories and 0 entries processed
xfsrestore: directory post-processing
xfsrestore: restore complete: 0 seconds elapsed
xfsrestore: Restore Summary:
xfsrestore: stream 0 /root/home.xfs_dump OK (success)
xfsrestore: Restore Status: SUCCESS [root@localhost ~]# df -Th #核对现在逻辑卷文件系统的情况
Filesystem Type Size Used Avail Use% Mounted on
devtmpfs devtmpfs 7.9G 0 7.9G 0% /dev
tmpfs tmpfs 7.9G 0 7.9G 0% /dev/shm
tmpfs tmpfs 7.9G 8.9M 7.9G 1% /run
tmpfs tmpfs 7.9G 0 7.9G 0% /sys/fs/cgroup
/dev/mapper/centos-root xfs 90G 3.0G 87G 4% /
/dev/sda2 xfs 1014M 131M 884M 13% /boot
/dev/sda1 vfat 200M 12M 189M 6% /boot/efi
tmpfs tmpfs 1.6G 0 1.6G 0% /run/user/0
/dev/mapper/centos-home xfs 24G 33M 24G 1% /home
[root@localhost ~]#
#若有必要，使用uuid挂载
[root@localhost ~]# grep home /etc/fstab
/dev/mapper/centos-home /home xfs defaults 0 0
[root@localhost ~]# blkid|grep home
/dev/mapper/centos-home: UUID="39916644-f3eb-42c1-a940-8749395b88f9" TYPE="xfs"
xfsdump也可以面交互执行
-L ：xfsdump 记录每次备份的 session 标头，这里可以填写针对此文件系统的简易说明
-M ：xfsdump 可以记录存储媒体的标头，这里可以填写此媒体的简易说明
[root@localhost ~]# xfsdump -f ~/home.xfs_dump01 /home -L home_dump -M root_dir
xfsdump: using file dump (drive_simple) strategy
xfsdump: version 3.1.7 (dump format 3.0) - type ^C for status and control
xfsdump: level 0 dump of localhost.localdomain:/home
xfsdump: dump date: Wed Oct 26 23:39:40 2022
xfsdump: session id: fa67f2be-0efe-4d23-b096-0fb0e3d12558
xfsdump: session label: "home_dump"
xfsdump: ino map phase 1: constructing initial dump list
xfsdump: ino map phase 2: skipping (no pruning necessary)
xfsdump: ino map phase 3: skipping (only one dump stream)
xfsdump: ino map construction complete
xfsdump: estimated dump size: 20800 bytes
xfsdump: creating dump session media file 0 (media 0, file 0)
xfsdump: dumping ino map
xfsdump: dumping directories
xfsdump: dumping non-directory files
xfsdump: ending media file
xfsdump: media file size 21352 bytes
xfsdump: dump size (non-dir files) : 0 bytes
xfsdump: dump complete: 0 seconds elapsed
xfsdump: Dump Summary:
xfsdump: stream 0 /root/home.xfs_dump01 OK (success)
xfsdump: Dump Status: SUCCESS
[root@localhost ~]#
lvresize
-L ：指定逻辑卷的大小, 单位为“kKmMgGtT”字节
-l ： 指定逻辑卷的大小单位为PE
[root@localhost ~]# vgs
VG #PV #LV #SN Attr VSize VFree
centos 2 4 0 wz--n- <129.80g 1020.00m
[root@localhost ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
home centos -wi-ao---- 24.00g
root centos -wi-ao---- 90.00g
sdbtest centos -wi-a----- 2.00g
swap centos -wi-ao---- 12.80g
[root@localhost ~]# lvresize -L 1g sdbtest
Please specify a logical volume path.
Run `lvresize --help' for more information.
[root@localhost ~]# lvresize -L 1g /dev/centos/sdbtest -f
WARNING: Reducing active logical volume to 1.00 GiB.
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Size of logical volume centos/sdbtest changed from 2.00 GiB (512 extents) to 1.00 GiB (256 extents).
Logical volume centos/sdbtest successfully resized.
[root@localhost ~]# lvresize -L 1.5g /dev/mapper/centos-sdbtest
Size of logical volume centos/sdbtest changed from 1.00 GiB (256 extents) to 1.50 GiB (384 extents).
Logical volume centos/sdbtest successfully resized.
[root@localhost ~]# lvresize -L -0.5g /dev/mapper/centos-sdbtest -f
WARNING: Reducing active logical volume to 1.00 GiB.
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Size of logical volume centos/sdbtest changed from 1.50 GiB (384 extents) to 1.00 GiB (256 extents).
Logical volume centos/sdbtest successfully resized.
[root@localhost ~]# lvresize -l +100%free /dev/mapper/centos-sdbtest -f
Size of logical volume centos/sdbtest changed from 1.00 GiB (256 extents) to <3.00 GiB (767 extents).
Logical volume centos/sdbtest successfully resized.
[root@localhost ~]#
[root@localhost ~]# ll -d /dev/mapper/centos-sdbtest
lrwxrwxrwx. 1 root root 7 Oct 27 14:26 /dev/mapper/centos-sdbtest -> ../dm-3
[root@localhost ~]# ll -d /dev/centos/sdbtest
lrwxrwxrwx. 1 root root 7 Oct 27 14:26 /dev/centos/sdbtest -> ../dm-3
[root@localhost ~]# ll -d /dev/dm-3
brw-rw----. 1 root disk 253, 3 Oct 27 14:26 /dev/dm-3
[root@localhost ~]#
指定只备份分区中某个目录
参数：-s 文件路径 只对指定的文件进行备份，-s指定时，路径写的是相对路径（-s 可以是文件或目录）
[root@localhost sdb1]# xfsdump -f /opt/dump_grub2 -s grub2/grub.cfg /boot -L dump_grub2 -M boot-sda1
备份成功后，我们可以在/var/lib/xfsdump/inventory 目录下看到生成的档案信息
[root@localhost sdb1]# ls /var/lib/xfsdump/inventory/
0180aae6-80c6-472f-a031-c79f271f8177.InvIndex
a5398b8f-e1ae-49a4-9d70-5f1fc5a68194.StObj
a5c5b8d4-6656-4023-b576-96593b9440b8.StObj
ba6ae155-c50d-440d-802f-7111a5cd3d03.InvIndex
fstab
[root@localhost sdb1]# xfsdump -I # 查看备份信息
当然如果遇到挂载点繁忙，可以使用fuser或lsof去查看，或者直接umount -lf 挂载点
fuser 可以显示出当前哪个程序在使用磁盘上的：
某个文件
挂载点
甚至网络端口
