Performing partial resynchronization

When the probe is disconnected or restarted, it will perform a full resync at startup. This normally pulls a lot of active alarms from the Nokia NSP server and some of these events have already been received while the probe running previously. The probe can be configured to perform a partial resync at startup based on the last event received timestamp stored in a persistent file.

When partial resync is enabled, during resync, the probe will check whether DataBackupFile exists and has a valid value of the last event received time. If it does, the probe will retrieve the last event received timestamp from persistent file and append the partial resync uri with alarmFilter=lastTimeDetected>=resyncTimestamp in the resync request.

Every probe has a check subscription feature controlled by the HeartbeatInterval property. During check subscription, the probe stores the last received event timestamp into the DataBackupFile. Thus, the last event received time is based on the check subscription interval, for example: saved last event received time every 120s (if HeartbeatInterval = 120). When partial resync is enabled, the HeartbeatInterval property must be set to 120 (in seconds) or greater so that the databackup file will not be updated frequently which may impact probe performance and stability.

To enable the partial resync feature, use the following steps:

Configure probe property as below:

DataBackupFile: "/opt/IBM/tivoli/netcool/omnibus/var/nspPartialResync"
PartialResync: "true"
HeartbeatInterval: 120

Create an empty file as defined in DataBackupFile, for example:

/opt/IBM/tivoli/netcool/omnibus/var/nspPartialResync

Make sure the user that executes the probe start command has read/write permission to this file.
Check the resync request in $OMNIHOME/java/conf/nokiaNspRestMultiChannelHttpTransport.json (RESYNC.RESYNC_FAULT_MANAGEMENT_ALARMS.uri)

If there is no alarm filter customization made in the resync uri, the probe will append the partial resync alarm filter in the URI, for example:
```
?alarmFilter=lastTimeDetected%2520%253E%2520<LastResyncTime>
```
If there is alarm filter customization made in the resync uri, you need to append the following string to your resync URI for partial resync to work correctly:
```
and%2520lastTimeDetected%2520%253E%2520<LastResyncTime>%2520
```

For example:

Change the following lines:

"RESYNC":
   {
        "RESYNC_FAULT_MANAGEMENT_ALARMS":
        {
            "uri":"https://host:port/FaultManagement/rest/api/v2/alarm
s/details?alarmFilter=alarmName%2520like%2520'%2525Equipment%2525'and%2520severity%2520%253D%2520'major'%2520",
      ...

to:

"RESYNC":
   {
        "RESYNC_FAULT_MANAGEMENT_ALARMS":
        {
            "uri":"https://host:port/FaultManagement/rest/api/v2/alarm
s/details?alarmFilter=alarmName%2520like%2520'%2525Equipment%2525'and%2520severity%2520%253D%2520'major'%2520and%2520lastTimeDetected%2520%253E%2520<LastResyncTime>%2520",
      ...

Partial resync is a configurable enhancement to utilize the Netcool internal heartbeat interval as lastTimeDetected attribute value to retrieve the latest alarms. Netcool and NSP systems must be synchronized for the feature to work accurately. The limitation is that if there is any drift between system times, data could be missed. The probe server time must be in synch with the NSP server time.