问题描述
环境信息：
1）/dev/mapper/dt-libvirt ext4 295G 101G 179G 37% /var/lib/libvirt
2）我们需要将其缩小到 110G 磁盘空间；
3）操作系统：Ubuntu 21.04
解决方案
注意事项
磁盘调整操作有风险，请注意数据**备份**！
为了校验数据一致性，在磁盘调整之前与之后，我们都会执行如下脚本，用于检查数据一致性：
# find ./ -type f -print0 | xargs -0 -i md5sum '{}'
第一步、缩小文件系统
systemctl stop libvirtd.service # 移除磁盘占用，否则无法 umount umount /var/lib/libvirt # e2fsck -f /dev/mapper/dt-libvirt e2fsck 1.45.7 (28-Jan-2021) Pass 1: Checking inodes, blocks, and sizes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts Pass 5: Checking group summary information /dev/mapper/dt-libvirt: 54/19660800 files (0.0% non-contiguous), 27925391/78643200 blocks # resize2fs /dev/mapper/dt-libvirt 110G resize2fs 1.45.7 (28-Jan-2021) Resizing the filesystem on /dev/mapper/dt-libvirt to 28835840 (4k) blocks. The filesystem on /dev/mapper/dt-libvirt is now 28835840 (4k) blocks long.
第二步、缩小分区
针对普通分区：通过 cfdisk 命令，重新创建分区表即可。
针对 LVM 环境：
# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert home dt -wi-ao---- 50.00g libvirt dt -wi-a----- 300.00g local dt -wi-ao---- 50.00g opt dt -wi-ao---- 50.00g srv dt -wi-ao---- 200.00g # lvreduce -L 110G /dev/dt/libvirt WARNING: Reducing active logical volume to 110.00 GiB. THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce dt/libvirt? [y/n]: y Size of logical volume dt/libvirt changed from 300.00 GiB (76800 extents) to 110.00 GiB (28160 extents). Logical volume dt/libvirt successfully resized. # lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert home dt -wi-ao---- 50.00g libvirt dt -wi-a----- 110.00g local dt -wi-ao---- 50.00g opt dt -wi-ao---- 50.00g srv dt -wi-ao---- 200.00g
参考文献
LVM Resize – How to Decrease an LVM Partition
How to Shrink an ext2/3/4 File system with resize2fs – Red Hat Customer Portal
partitioning – Shrinking ext4 partition on command line – Ask Ubuntu
How to Resize a Partition using fdisk – Red Hat Customer Portal