Pre-patching tasks in a Linux environment are critical to ensuring a smooth and successful patching process. These tasks help in minimizing downtime, preventing issues during the patching, and ensuring the system's stability. Here’s a checklist of common pre-patching tasks you should perform:
1. Backup Critical Data
- Full System Backup: Perform a full system backup, including configuration files, databases, and critical application data.
- Verify Backup Integrity: Ensure that the backup is complete and can be restored if necessary.
2. Review Patch Notes
- Understand the Patch: Review the release notes and documentation for the patches you plan to apply. Understand what is being updated and any potential impact on your system.
- Check Dependencies: Verify that all dependencies for the patches are met, including hardware, software, and configuration requirements.
3. Check System Health
- Disk Space: Ensure there is sufficient disk space available, especially on
/var
,/tmp
, and/boot
if you are applying kernel patches. - System Load: Check the system load to ensure it is not under heavy use. Patching during low-usage periods is advisable.
- Logs: Review system logs (
/var/log/messages
,/var/log/syslog
, etc.) for any existing errors or issues that might affect the patching process.
4. Verify System Configurations
- Current Patch Level: Check the current patch level of the system to understand what patches have already been applied.
- Service Status: Verify the status of critical services to ensure they are running as expected.
- Network Configuration: Ensure network connectivity, especially if patches need to be downloaded from a repository or if remote access is required post-patching.
5. Plan for Downtime
- Schedule Maintenance Window: Plan a maintenance window during off-peak hours to minimize the impact on users.
- Notify Stakeholders: Inform all stakeholders about the planned downtime and expected impact on services.
6. Test Patch Installation in a Non-Production Environment
- Staging Environment: If possible, test the patch installation in a staging environment that mirrors your production setup.
- Verify Functionality: After applying the patch in the test environment, verify that all critical applications and services function as expected.
7. Snapshot Virtual Machines (if applicable)
- Create VM Snapshots: If you are running the Linux system on a virtual machine, create a snapshot before applying patches. This allows you to quickly roll back in case of failure.
8. Document System State
- List Running Processes: Document the current running processes and resource usage (
ps aux
,top
). - Configuration Files: Backup important configuration files (e.g.,
/etc/
, application configs). - Current Kernel Version: Note down the current kernel version (
uname -r
) if you are patching the kernel.
9. Prepare Rollback Plan
- Rollback Procedures: Document the steps to roll back the patches if something goes wrong.
- Validate Rollback: Ensure that the rollback procedures are tested and validated.
10. Disable Unnecessary Services
- Stop Non-Critical Services: Temporarily stop non-critical services to reduce the risk of conflicts during patching.
11. Ensure Remote Access
- Test SSH Access: Make sure you have a working SSH connection to the server in case you need to manage the patching remotely.
- Console Access: Ensure you have console access in case the server becomes unresponsive over the network.
12. Verify Patch Repository and Access
- Repository Access: Ensure that your system has access to the correct repositories where the patches are hosted.
- Package Manager Update: Run an update command to make sure your package manager (
yum
,apt
, etc.) is up-to-date.
13. Review Security Policies
- Firewall Rules: Review and temporarily adjust firewall rules if needed to ensure that patching does not get blocked.
- SELinux/AppArmor: Ensure that SELinux or AppArmor policies do not interfere with the patching process.
14. Check and Update Documentation
- System Documentation: Update your documentation with the current system state, the planned patches, and the expected outcomes.
15. Pre-Patching Script Execution (if any)
- Run Pre-Patch Scripts: Execute any pre-patching scripts or commands required by your organization or software vendors.
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