HANA Data and Log Reclaim (Procedure in HA DB cluster).pdf

SAP hana

1. Data Reclaim process
overview in HA HANA DB
Cluster
Prepared By Nava Kishore Reddy @ SAP Basis HANA Consultant

2. Purpose of Data Re-claim/ Why we do Re-claim?
•To free up some space from Hana DB
•To avoid adding the new storage space to /hana/data (which directly
indicates cost)
•Data Re-claim is also called as or referred to as Defragmentation.

3. Reasons/causes why fragmentation space
available to reclaim/defragment?
•Reduction of business data, e.g. due to archiving and deletion
operations (SAP Note2388483)
•Cleanup after blocked garbage collection (SAP Note2169283)
•Table optimization (i.e. merge, compression) of a large table (SAP
Note2057046), requiring temporarily double space
•Snapshots / savepoints preserved for a longer time (SAP
Note2100009), resulting in an increased amount of shadow pages
Because the allocated space won't automatically
reduce, we need to go for data re-claim

6. To check the un-used space
1969700 - SQL Statement Collection for SAP HANA

8. CRM Status
Place the HA cluster in maintenance mode in OS level. And can be
verified using the command crm status

9. •Stop DB (secondary-dbc2) & Un-register dbc2
•Stop DB (dbr1) & Un-register dbr1
•Then disable replication from primary dbc1
Before re-claim steps:

10. Data Reclaim: execute in dbc1 (primary)
•ALTER SYSTEM RECLAIM DATAVOLUME 120 DEFRAGMENT
•ALTER SYSTEM RECLAIM DATAVOLUME 110 DEFRAGMENT
•ALTER SYSTEM RECLAIM DATAVOLUME 105 DEFRAGMENT
•Below is the Sql query if we want to go for Log re-claim
•ALTER SYSTEM RECLAIM LOG

13. •Enable replication in dbc1(primary)
•Register in dbc2 & start DB
•Register in dbr1 & start DB
After re-claim steps:

14. Replication in progress

15. Remove DB cluster from maintenance mode
and validate using CRM status in OS
Replication completed and is in Sync

16. •Thank You All !
By
Nava Kishore Reddy @ SAP Basis HANA
Consultant