10.5. 在未成功升级后创建回滚引导条目

流程

1. 将快照与原始卷合并：

   # lvconvert --merge rhel/root_snapshot_before_changes
     Logical volume rhel/root_snapshot_before_changes contains a filesystem in use.
     Delaying merge since snapshot is open.
     Merging of thin snapshot rhel/root_snapshot_before_changes will occur on next activation of rhel/root.

   警告

   合并快照后，您必须继续这个流程中的所有剩余步骤来防止数据丢失。

2. 为合并的快照创建一个回滚引导条目：

   # boom create --backup --title "RHEL Rollback" --rootlv rhel/root
   WARNING - Boom grub2 integration is disabled in '/boot/../etc/default/boom'
   WARNING - Options for BootEntry(boot_id=1e1a9b4) do not match OsProfile: marking read-only
   WARNING - Options for BootEntry(boot_id=1ccc554) do not match OsProfile: marking read-only
   WARNING - Options for BootEntry(boot_id=4ea37b9) do not match OsProfile: marking read-only
   WARNING - Options for BootEntry(boot_id=e22dd61) do not match OsProfile: marking read-only
   Created entry with boot_id 6c44638:
     title RHEL Rollback
     machine-id b1dcec73886b45218892b1a7bbfa0dee
     version 4.18.0-513.24.1.el8_9.x86_64
     linux /vmlinuz-4.18.0-513.24.1.el8_9.x86_64.boom0
     initrd /initramfs-4.18.0-513.24.1.el8_9.x86_64.img.boom0
     options root=/dev/rhel/root ro rd.lvm.lv=rhel/root rhgb quiet crashkernel=1G-4G:192M,4G-64G:256M,64G-:512M

   忽略所有警告消息，请参阅 RHEL-35983。

3. 重启机器以恢复操作系统状态：

   # reboot

   • 系统重启后，从 GRUB 屏幕中选择 RHEL Rollback 引导条目。

   • 当 root 逻辑卷处于活动状态时，系统会自动启动快照合并操作。

     重要

     当合并操作启动时，快照卷不再可用。在成功引导 RHEL Rollback 引导条目后，Root LV 快照引导条目 不再工作。合并快照逻辑卷会破坏 Root LV 快照，并恢复原始卷的之前状态。

4. 完成合并操作后，删除未使用的条目，并恢复原始引导条目：

   1. 从 /boot 文件系统中删除未使用的 Red Hat Enterprise Linux 9 引导条目，并重建 grub.cfg 文件以使更改生效：

      # rm -f /boot/loader/entries/*.el9*

      # rm -f /boot/*.el9*

      # grub2-mkconfig -o /boot/grub2/grub.cfg
      Generating grub configuration file ...
      done

5. 成功回滚回系统后，删除 boom 快照，并回滚引导条目：

   # boom list -o+title
   WARNING - Options for BootEntry(boot_id=1e1a9b4) do not match OsProfile: marking read-only
   WARNING - Options for BootEntry(boot_id=1ccc554) do not match OsProfile: marking read-only
   WARNING - Options for BootEntry(boot_id=4ea37b9) do not match OsProfile: marking read-only
   BootID  Version                      Name                     RootDevice                             Title
   1e1a9b4 4.18.0-513.5.1.el8_9.x86_64  Red Hat Enterprise Linux /dev/mapper/rhel-root                  Red Hat Enterprise Linux (4.18.0-513.5.1.el8_9.x86_64) 8.9 (Ootpa)
   4ea37b9 4.18.0-513.24.1.el8_9.x86_64 Red Hat Enterprise Linux /dev/mapper/rhel-root                  Red Hat Enterprise Linux (4.18.0-513.24.1.el8_9.x86_64) 8.9 (Ootpa)
   c919f89 4.18.0-513.24.1.el8_9.x86_64 Red Hat Enterprise Linux /dev/rhel/root_snapshot_before_changes Root LV snapshot before changes
   6c44638 4.18.0-513.24.1.el8_9.x86_64 Red Hat Enterprise Linux /dev/rhel/root                         RHEL Rollback

   # boom delete c919f89
   WARNING - Options for BootEntry(boot_id=1e1a9b4) do not match OsProfile: marking read-only
   WARNING - Options for BootEntry(boot_id=1ccc554) do not match OsProfile: marking read-only
   WARNING - Options for BootEntry(boot_id=4ea37b9) do not match OsProfile: marking read-only
   Deleted 1 entry

   # boom delete 6c44638
   WARNING - Options for BootEntry(boot_id=1e1a9b4) do not match OsProfile: marking read-only
   WARNING - Options for BootEntry(boot_id=1ccc554) do not match OsProfile: marking read-only
   WARNING - Options for BootEntry(boot_id=4ea37b9) do not match OsProfile: marking read-only
   Deleted 1 entry

   忽略警告。详情请查看 RHEL-35983。