骤5 - 测试和检查

为了使逻辑卷已正确减少，请使用以下命令之一：

[jack@onitroad ~]# cat /proc/swaps
Filename                                Type            Size    Used    Priority
/dev/dm-1                               partition       1048572 0       -1

[jack@onitroad ~]# free -h
              total        used        free      shared  buff/cache   available
Mem:           754M        105M        474M         16M        174M        478M
Swap:          1.0G          0B        1.0G

步骤3 - 格式化新的 Swap LVM 逻辑卷

[jack@onitroad ~]# mkswap /dev/vg1/swap
mkswap: /dev/vg1/swap: warning: wiping old swap signature.
Setting up swapspace version 1, size = 1048572 KiB
no label, UUID=9d608205-2605-4129-8a9e-ae0d2a87f5fe

在本教程教程中，我们将介绍如何减少 CentOS 7/RHEL 7 服务器上的 lVM 交换分区。

任务：将 LVM 交换分区 /dev/vg1/swap 从 1.5 GiB 减少到 1 GiB

步骤1 - 禁用 LVM 交换分区

要禁用关联逻辑卷 /dev/vg1/swap 的交换，请以 root 身份运行以下命令：

[jack@onitroad ~]# swapoff -v /dev/vg1/swap
swapoff /dev/vg1/swap

步骤4 - 启用 Swap LVM 逻辑卷

[jack@onitroad ~]# swapon -va
swapon /dev/mapper/vg1-swap
swapon: /dev/mapper/vg1-swap: found swap signature: version 1, page-size 4, same byte order
swapon: /dev/mapper/vg1-swap: pagesize=4096, swapsize=1073741824, devsize=1073741824

步骤2 减少LVM逻辑卷

要减小 LVM 逻辑卷的大小，请运行以下命令

[jack@onitroad ~]# lvreduce /dev/vg1/swap -L -512M
  WARNING: Reducing active logical volume to 1.00 GiB.
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce centos/swap? [y/n]: y
  Size of logical volume vg1/swap changed from 1.50 GiB (384 extents) to 1.00 GiB (256 extents).
  Logical volume vg1/swap successfully resized.