Friday, June 10, 2011

The Best practices to reduce the patching downtime (Execution point view)

1)Use Hotpatch option:
where ever Possible apply the patches in the hotpatch mode (ihelp patches, One off patches (small patches) can be applied in hotpatch mode), In hotpatch mode there is no downtime required, Patch can be applied when the services are running.

Note : hotpatch mode is not suggested/supported for patching, It must be used in extreame situations.

2)Use adpatch options:
adpatch provides multiple options which can be used reduce the downtime, Eg: No compile DB, No Compile jsp...etc

These activies can be done later when the services are running.

3)Merge Patches:
Merging of the patches is very good option and it reduces the downtime significantly in case where we have Multiple patches to apply.

4)Increase the batch size during the patching:
Increasing the batch size to higher value (10000) will reduce the patch time by 10%.

5)Distributed AD can be used in Multi Node systems:
In case of multinode systems we can Distributed AD feature, In this method patch workers will spread and run in all the Applications nodes effectively utilizing the OS resources of others nodes as well.

6)Increase the OS resources (as possible) which help in increasing the the no.of parallel workers of the patch:
Having well sized OS resources such as CPU,Memory..etc will increase the patch runtime there by reduces the downtime.

7)Staged APPL_TOP:
A staged Applications system represents an exact copy of your Production system, including all APPL_TOPs as well as a copy of the Production database. Patches are applied to this staged system, while your Production system remains up. When all patches have been successfully applied to the test system, the reduced downtime for the Production system can begin.

Please Note:

i) Staged APPL_TOP only reduces the the time required to Apply the patch on Application Node only.(The database part of the patch requires downtime anyway)

ii)Usually Database portion of the patch takes 60-70% of the patching time, So by this method we can only reduce the 30-40% of the patch time,

iii) But staged APPL_TOP is only usefull in case of bulk patching or Upgrades,This approach is not a soultion to the small and day to day patching as this involves lot of preparation (cloning of the Production system to target) and synching back the APPL_TOP to Prod and it is a complex process.

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