Linux OS (RHEL) upgrade guidelines
1: Is any specific RPM's of RHEL required from RA perspective?
No, there is no explicit dependency, RA has on any specific RHEL RPM's
2: Do any specific instruction w.r.t. to application, while doing OS upgrade?
- The most general guidelines and practice is, to stop the applications before, OS level upgrade to avoid any soft locks on resources.
- The another check point is to make sure that firewall state and permission over install directory and user running application remain same, to what it was pre-upgrade of OS
Application Upgrade guidelines
- The NAC and NES should be on same version to work seamless.
- It is always recommended to upgrade NAC and NES to same version in same maintenance window to avoid any issue originating from version incompatibility.
- The NAC of lower version and NES of higher version is strictly prohibited.
- We restrain use of, NAC 6.6/6.7 with unsupported NES version example 6.4 as unsupported/EOS version are more supported, therefore these scenario are never QA'd.
- In any environment the number of agents are huge, compared to number of NAC and NES. Our recommendation to mitigate risk as below
- Firstly, upgrade OS & RA version on NAC/s and NES/s servers in one shot. Please refer to prevalent practices section below for more details.
- The agents upgrades can be delayed if time of maintenance window doesn't permit and can be upgraded in later maintenance window/s.
- During a maintenance window when upgrade is performed the system should be down as it will not be in a position to process any request. Please avoid scenario of submitting deployments/process execution when NAC, NES/s or Agent/s are undergoing upgrade as it will result in unexpected failures.
- The gap between, OS upgrades and running RA version on not compatible OS version should be reduced and if possible avoided, as these scenarios are not QA'd.
Prevalent practices/guidelines for upgrade(Below instructions are specific to customer infrastructure and process followed, please pick the appropriate judiciously)
- Backup of DB before upgrade (this is useful for quick rollback if needed)
- Backup of Install directory of NAC or NES (this is useful for quick restoration if needed)
- If you are using virtual environments, the snapshot of the VM's hosting NAC/NES can be taken and can be used as checkpoint for quick restoration.
- Create a backup
- Stop Applications
- OS Upgrade, if applicable
- Upgrade OS
- Do OS sanity testing
- Check user accounts, firewall and app install directory permissions (To be same as pre OS upgrade)
- Take snapshot or backup of NAC Install directory
- Upgrade Application, if applicable
- Upgrade RA to GA version
- If any RA cumulative patch is required to be applied, please apply the same
- Do sanity on RA Component
- Start Application and do sanity testing