Performing a snapshot restore with Db2 container commands

You can restore a snapshot backup of your Db2 database by putting your database in maintenance mode and restoring your volume snapshots.

1. Put your cluster in maintenance mode:

   DB2U_CLUSTER=$(oc get db2ucluster --no-headers | head -n1 | awk '{print $1}'); echo $DB2U_CLUSTER

   oc annotate db2ucluster $DB2U_CLUSTER db2u.databases.ibm.com/maintenance-pause-reconcile=true --overwrite

2. Scale down your deployment:

   DB2U_STS=$(oc get sts --selector="app=${DB2U_CLUSTER},type=engine" --no-headers | awk '{print $1}'); echo $DB2U_STS

   NUM_REPLICAS=$(oc get sts ${DB2U_STS} -ojsonpath={.spec.replicas})

   ETCD_STS=$(oc get sts --selector="app=${DB2U_CLUSTER},component=etcd" --no-headers | awk '{print $1}'); echo $ETCD_STS

   oc scale sts ${DB2U_STS} --replicas=0

   oc scale sts ${ETCD_STS} --replicas=0

3. Copy the existing PVC definitions:

   oc label pvc c-${DB2U_CLUSTER}-meta app=${DB2U_CLUSTER}

   oc label pvc c-${DB2U_CLUSTER}-backup app=${DB2U_CLUSTER}

   oc label pvc c-${DB2U_CLUSTER}-share app=${DB2U_CLUSTER}

   for PVC in $(oc get pvc -l app=$DB2U_CLUSTER --no-headers | awk '{print $1}'); do oc get pvc $PVC -oyaml > ${PVC}_copy.yaml ; done

4. Set your existing PVs reclaim policy to retain in case something goes wrong:

   for PV in $(oc get pv --no-headers | grep $DB2U_CLUSTER | awk '{print $1}'); do oc patch pv $PV -p "{\"spec\":{\"persistentVolumeReclaimPolicy\":\"Retain\"}}" ; done

   Important: Manually verify that each PV is set to retain or you are at risk of losing your data.
5. Delete the existing PVCs:

   oc delete pvc -l app=${DB2U_CLUSTER}

   CAUTION:

   Do this step only if you are confident that you are able to restore your volumesnapshots, and your PV reclaim policies are set to retain. If you are unsure, try the next step instead by restoring your volumesnapshots to dummy PVCs with different names first.
6. Restore your volumesnapshot to PVCs with the same name and namespace that you copied in step 3.
   The steps will differ depending on your provider:

   • OpenShift® Data Foundation
   • Portworx
   • IBM Spectrum® Scale CSI
   • IBM® Cloud File Storage
7. Scale up your deployment:

   oc scale sts ${ETCD_STS} --replicas=${NUM_REPLICAS}

   oc scale sts ${DB2U_STS} --replicas=${NUM_REPLICAS}

8. Bring the database out of write-suspend after restoring:

   CATALOG_POD=$(oc get po -l name=dashmpp-head-0,app=${DB2U_CLUSTER} --no-headers | awk '{print $1}')

   oc exec -it ${CATALOG_POD} -- manage_snapshots --action restore

9. Exit maintenance mode:

   oc annotate db2ucluster $DB2U_CLUSTER db2u.databases.ibm.com/maintenance-pause-reconcile=false --overwrite