CentOS FetchLinux恢复方法

Note: “FetchLinux” is not a standard Linux distribution or recovery tool—likely a miswriting of CentOS (a RHEL-based distro) or a tool like FetchXML (used in Microsoft Power Platform). Below are recovery methods for CentOS systems and data recovery (assuming “FetchLinux recovery” refers to system/data restoration):

I. CentOS System Recovery Methods

1. Boot from Installation Media (Rescue Mode)

If the system fails to boot, use a CentOS installation DVD/USB to enter rescue mode:

• Insert the media, reboot the server, and access the BIOS/UEFI to set CD-ROM/USB as the first boot device.
• At the boot menu, select Troubleshooting > Rescue a CentOS system.
• Choose 3) Skip to shell to access the command line.
• Mount the original system partition (e.g., mount /dev/sda2 /mnt/sysimage) and chroot into it (chroot /mnt/sysimage).
• From here, you can reinstall the bootloader (GRUB), repair file systems (fsck), or restore configuration files.

2. Use Yum History to Undo Changes

If the issue stems from recent package installations/updates, use yum history to revert changes:

• Run yum history list to view past operations (shows transaction IDs).
• Identify the problematic transaction (e.g., a failed update) and run yum history undo <transaction_id> to undo it.
• This rolls back software packages to their previous state, fixing issues caused by broken dependencies or incorrect configurations.

3. Restore from Backups

If you have regular backups (e.g., full system images or file-level backups), restore them to revert the system to a stable state:

• For file-level backups (e.g., made with tar):

  tar xvpfz backup.tgz -C /  # Extracts the backup to the root directory
  

• For system images (e.g., created with Clonezilla or Acronis): Boot from the image and restore it to the system disk.
• Ensure backups are stored offline or on a separate device to avoid data corruption during system failures.

4. Fix GRUB Bootloader Issues

If the system fails to boot due to a corrupted GRUB, repair it via rescue mode:

• Mount the system partition (mount /dev/sda2 /mnt/sysimage).
• Reinstall GRUB to the Master Boot Record (MBR) of the disk:

  grub2-install /dev/sda  # Replace /dev/sda with your boot disk
  grub2-mkconfig -o /boot/grub2/grub.cfg  # Regenerate the GRUB config file
  

• Exit chroot and reboot the system.

II. CentOS Data Recovery Methods

1. Stop Writing to the Affected Partition

When data is deleted, immediately unmount the partition (if possible) to prevent new data from overwriting the deleted files:

umount /dev/sda1  # Replace with the affected partition (e.g., /home)

For system partitions (e.g., /), boot into rescue mode to unmount them safely.

2. Use Extundelete to Recover Deleted Files

Extundelete is a tool for recovering files from ext3/ext4 file systems (common in CentOS):

• Install Extundelete:

  sudo yum install extundelete
  

• Unmount the affected partition (critical for success).
• Run Extundelete to recover files:

  sudo extundelete /dev/sda1 --restore-all  # Recovers all deleted files in the partition
  

• Check the /home/extundelete/recovered_files/ directory for restored files.

3. Use TestDisk for Lost Partitions/Files

TestDisk is a powerful tool for recovering lost partitions and repairing boot sectors:

• Install TestDisk:

  sudo yum install testdisk
  

• Run TestDisk and follow the interactive prompts:
  • Select the affected disk.
  • Choose Intel/PC partition table (for most systems).
  • Select Analyze to scan for lost partitions.
  • If a partition is found, select Write to restore it to the partition table.
• TestDisk can also recover files from formatted/recovered partitions.

4. Restore from File-Level Backups

If you have backups of specific directories (e.g., /home, /var), restore them using tar or rsync:

• For tar backups:

  tar xvpfz home_backup.tgz -C /home  # Restores /home from a tar archive
  

• For rsync backups (from a remote server):

  rsync -avz user@remote:/backup/home/ /home/  # Copies files from the remote backup
  

Key Notes

• Prevention is critical: Regularly back up your system (using tools like tar, rsync, or commercial solutions) to minimize data loss.
• Act quickly: The longer you wait after data deletion, the higher the chance of overwriting.
• Professional help: If you’re unsure about recovery steps or dealing with critical data, consult a Linux administrator or data recovery specialist.

Let me know if you meant a different tool (e.g., FetchXML) or need further clarification on any step.