How to switch back from using EMS to using NAS again
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How to switch back from using EMS to using NAS again

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Article ID: 199273

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Updated On:

Products

DX Unified Infrastructure Management (Nimsoft / UIM) Unified Infrastructure Management for Mainframe CA Unified Infrastructure Management SaaS (Nimsoft / UIM)

Issue/Introduction

  • We have configured our UIM DEV environment to process alarm messages via EMS upon recommendation via one of the support cases we opened, but it did resolve the issue we were having at that time.

  • Now we are looking to fallback from EMS to NAS to match production. Please let us know the steps to switch back to NAS from EMS.

Environment

DX UIM 20.4.x / 23.4.x

NAS and EMS 20.4.x or later

 

Cause

  • Customer needed EMS-focused configuration to be reverted back to the NAS
  • This may also be required if and when customers (or support) notice that the alarm Subjects in later versions are incorrect!!!
  • This is usually evidenced by the nas message Subject showing as 'alarm'1 instead of its correct Subject of 'alarm2'

Resolution

Out of the box/defaults you should see in the hub with nas and ems installed, but not reconfigured for EMS, will display the proper Subjects like this:

 

Here is a quick checklist for message queue Subject names for nas and alarm_enrichment probes with NO EMS being used:

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1. alarm_enrichment probe uses a Subject of alarm

2. nas probe uses a Subject of alarm2

So by default, the alarm_enrichment probe uses the "alarm" Subject and forwards messages to the "alarm2" subject for the nas probe.

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Before ems deployment, alarm messages flow through the UIM environment in the following manner:

  • probes and the baseline_engine send alarm messages with the Subject "alarm"

  • The alarm_enrichment probe receives the alarm messages, enriches them with user-defined data, and then changes the alarm message subject to "alarm2"

  • The nas probe receives the alarm2 messages and performs further alarm processing


Post-reconfiguration, the alarm message Subjects used should be set as described below:

********************************************************************************************************

1.alarm_enrichment probe: Change the enrichment_subject key via nas Raw Configure mode from "alarm1" to "alarm"

2.nas probe continues to use a Subject of alarm2 (so normally no change is required here)

********************************************************************************************************

In most cases, if you reconfigure UIM in favor of using the NAS instead of the ems probe in your UIM environment please be aware that the alarm_routing_service probe and queue not 'automatically' removed.

The 'enrichment_subject' key in the nas configuration file (nas.cfg) remains or persists as "alarm1" and that is undesireable.

In that case, use the following procedure to ensure that no alarms are lost or mismanaged.

Follow these steps:

This procedure assumes that legacy alarm messages are currently being sent to the ems probe.

If you did not:

a. Change the default routing destination to ems, and/or

b. Configure any routing rules to send alarms to ems,

Then-> Skip to step 2, otherwise:

  1. In the alarm_routing_service configuration file, change the default destination back to nas and remove any routing rules. This action prevents alarms from getting 'stuck' in the legacy_alarm queue
  2. Enter the Raw Configure menu for the nas probe
  3. Navigate to the nas <setup> folder
  4. Change the enrichment_subject key from "alarm1" to "alarm"
  5. If you had already deactivated the nas probe, redeploy and reactivate it
  6. Redeploy the correct ems probe version for your DX UIM version, e.g., ems v23.4.3.

Note that if you are running the spectrumgtw, you must have the ems probe installed on the Primary hub as well.

Additional Information

In some environments, if you run through the above process but after a restart of the nas/alarm_enrichment, the alarm_enrichment probe reverts back to a Subject of alarm1, follow these steps to avoid that issue:

1. Open nas probe in Raw Configure.
    Change the value of the "enrichment_subject" key (under the setup section) from "alarm1" to "alarm", and save the change.

2. If the trellis probe is still present, Deactivate the trellis probe, delete trellis probe and delete the trellis probe folder (<UIM>/probes/service/trellis)

3. Deploy the trellis probe to the Primary UIM hub and Activate it (this ONLY applies to v20.4 CU6 or earlier DX UIM releases).

4. Deploy nas-api-service package to the Primary UIM hub (this ONLY applies to UIM v9.02 or earlier DX UIM releases)

5. Deploy Spectrum UIM Services package to the Primary UIM hub. (This ONLY applies to spectrumgtw v8.69 or earlier).
    The version of 'Spectrum UIM Services' package should match the version of the Spectrum Gateway probe.

6. Open the controller GUI on the Primary hub and choose the 'Status' Tab and then 'Installed Packages' and make sure there is no 'alarm_routing_service' package still installed. If so, remove it using the probe utility (Ctrl-P) and the probe callback 'inst_pkg_remove'

7. Open hub probe GUI in the Primary hub, go to [Queues] tab, highlight [alarm-routing-service] queue, delete the queue and then Save it.

8. Lastly, EMPTY the alarm-routing-service queue a few times until ALL of the queued alarms in that queue are gone. Do this via the Hub Status tab and after a hub restart, the queue will disappear from the Status Tab window and this is the expected result.

Then alarm_enrichment will no longer revert back to the message Subject of alarm1!!!

Shown below is a screenshot of the hub GUI in IM showing an example of the default queues and their expected message Subjects for reference.

nas default message Subject is always 'alarm2,' and alarm_enrichment is 'alarm.'

 EMS history and impact

  • The ems probe is a core event and alarm management service for UIM.

  • As of UIM 8.5.1 release or earlier, ems (event management) was a required UIM component that was responsible for sending nas alarms to OC.

  • Unless you need to perform event and alarm management using ems and/or currently have ruby scripts that manipulate alarms, you can switch back from using ems to using the nas. 

  • Today, most production customers do NOT use the ems probe other than for its OOTB, default role and purpose, routing legacy alarms, specifically those from NAS (alarm_enrichment), to either EMS itself, NAS, or a combination of both, depending on the configured routing settings.

    • alarm_routing_service deprecation

      • As a result, the alarm_routing_service probe is considered 'optional' and no longer used when switching back to using just the nas.

      • The alarm_routing_service is an optional probe that is used with the ems probe. As mentioned, the alarm_routing_service routes LEGACY alarm messages to the ems probe for processing.

  • There should be zero adverse impact to a production, Test/DEV environment when making this change as evidenced by support and customers following this process many times over the past 2 years. That said, you can still open a case and request assistance from support if something goes wrong during the process described above. Note that you will never have to run through this process again unless someone seriously ALTERS the nas configuration and/or changes the message Subjects manually.

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