Scope

Solution Manager 7.1 SP05 and higher

Terminology

• The term 'host' does NOT designate a network alias. Hosts must have their own IP addresses.
• A 'virtual host' designates a simulated host running for example on top of a VMware.
• A 'logical host' designates a network/host configuration which associates a physical host with one or more additional host names and dedicated IP addresses. This is used, for example, to be able to move systems from one physical host to another.
  N.B.: To find the host name of an ABAP system, use transaction sm51, and for Java systems refer to the System Info Web page.

Introduction

Solution Manager 7.1 SP05 introduced a so called Agents-on-the-fly feature. It offers a built-in infrastructure/principle to put in place appropriate Diagnostics Agent landscapes in the context of High Availability environments, where SAP Systems or DB switch/fail-overs are occurring. With this Solution Manager built-in feature there is no more need to configure for example some proprietary High Availability Managers or to adapt failover scripts.

Note that the Agents On-the-fly feature could also be useful in the context of Physical/Virtual hosts running a high number of Logical hosts.

Prerequisite

How to proceed in case Diagnostics Agents are already installed for the Managed Systems?

You will find in the following two tables a check list of all important actions and possible pinpoints to take care of. In case you will put in place Agents On-the-fly, you need to evaluate the Managed system environment : "High Availability" and/or "Physical/Virtual hosts running a high number of Logical hosts". Depending on this environment, either use the recommendations of the first table, or the second below table.

Diagnostics Agent installation/deployment strategy in the context of Agents On-the-fly

Installation Strategy in an High Availability context (system switch over)

• N.B.: The above situation description applies in the context of one Solution Manager system. In case the Managed systems/hosts should be visible in one additional Solution Manager system, one additional Diagnostics Agent has to be installed using a new different System-ID. And this new additional Agent will then be configured in the solman_setup of that additional Solution Manager system, like described above.
• N.B.: The "Display resulting host list" button in step "Enter System Parameters" shows the list of logical hostnames for which an Agent On-the-fly will be created (only at moments where these logical hostnames are associated to underlying Physical or Virtual Host). Also note that the displayed hostname list is computed based on the Hostnames attribute returned by the following SAP HOST Agent command. It therefore does NOT include any network hostname alias. In case of doubts feel free to execute that command on the Physical or Virtual Host.
  • On Windows:
     "C:\Program Files\SAP\hostctrl\exe\saphostctrl.exe" -function GetComputerSystem
  • On Unix:
    /usr/sap/hostctrl/exe/saphostctrl -function GetComputerSystem

Installation Strategy outside any High Availability context (system switch over)

• N.B.: The above situation description applies in the context of one Solution Manager system. In case the Managed systems/hosts should be visible in one additional Solution Manager system, one additional Diagnostics Agent has to be installed using a new different System-ID. And this new additional Agent will then be configured in the solman_setup of that additional Solution Manager system, like described above.
• N.B.: The "Display resulting host list" button in step "Enter System Parameters" shows the list of logical hostnames for which an Agent On-the-fly will be created (only at moments where these logical hostnames are associated to underlying Physical or Virtual Host). Also note that the displayed hostname list is computed based on the Hostnames attribute returned by the following SAP HOST Agent command. It therefore does NOT include any network hostname alias. In case of doubts feel free to execute that command on the Physical or Virtual Host.
  • On Windows:
    "C:\Program Files\SAP\hostctrl\exe\saphostctrl.exe" -function GetComputerSystem
  • On Unix:
    /usr/sap/hostctrl/exe/saphostctrl -function GetComputerSystem

Important remark concerning Java Managed systems on logical hosts

Agents On-the-fly concept

Concept

When for a given Diagnostics Agent (installed for a Physical or Virtual host) the Agents On-the-fly feature is enabled, this Agent can potentially run additional Diagnostics Agent processes (Agents On-the-fly), under his SID and Instance Number. These additional processes are considered as being Diagnostics Agents On-the-fly or "Nodes".
The rule for having additional or less of these Agents On-the-fly at a given point in time is as follow. Whenever a new (Logical) hostname is visible on the underlying (Physical or Virtual) host, the Diagnostics Agent (installed initially), will automatically create one additional Agent On-the-fly. However when this Logical hostname is no longer associated with that underlying (Physical or Virtual) host, the Diagnostics Agent will stop and remove again the associated Agent On-the-fly.

N.B.:

• With this approach, the number of Diagnostics Agent instances (allocated Instance Number) on a Physical or Virtual, is also independent of the number of Managed Systems/Logical Hosts.
• Two Agents On-the-fly will have the same memory footprint as two "standard" Diagnostics Agents. However, note that the Diagnostics Agent installed on the underlying (Physical or Virtual) host has to be additionally considered for the overall memory footprint. At disk space level the Agents footprint will be less given that the SAPJVM & Kernel binaries are shared.
• Remember that network hostname aliases will not be considered. For further details refer also to the below "Enable the Agents On-the-fly feature" item description in the Setup storyboard.

Example

Landscape components

Hostname layout

Failover scenario

1. Cluster Manager detects/triggers a DB failover
2. Logical Host/IP is moved to failover cluster node
3. DB instance is started on failover cluster node
4. Diagnostics Agent (DAA) detects a change in the Logical Host allocation
5. Agent On-the-fly on DAA is stopped/removed and created/started on DAB, according to the new cluster layout
6. Normal operation can continue transparently

Setup Story Board

solman_setup transaction entrance

N.B.: The values P,V or L in the column "Host Type" mean respectively Physical, Virtual or Logical host. See also the initially presented terminology.

Assign Diagnostics Agent installed on Physical or Virtual Host level

Enable the Agents On-the-fly feature

N.B.: The "Display resulting host list" button in step "Enter System Parameters" shows the list of logical hostnames for which an Agent On-the-fly will be created (only at moments where these logical hostnames are associated to underlying Physical or Virtual Host). Also note that the displayed hostname list is computed based on the Hostnames attribute returned by the following SAP HOST Agent command. It therefore does NOT include any network hostname alias. In case of doubts feel free to execute that command on the Physical or Virtual Host.

• On Windows:
  "C:\Program Files\SAP\hostctrl\exe\saphostctrl.exe" -function GetComputerSystem
• On Unix:
  /usr/sap/hostctrl/exe/saphostctrl -function GetComputerSystem

Finally, with SAP Solution Manager 7.1 SP10 or higher, remind to start the "Agent On-the-fly Administration" UI, in order to double check whether the expected Agents On-the-fly are created and connected. It is accessible via the "Advanced Settings" tab, within the Agent Administration UI.

Or, prior to SAP Solution Manager 7.1 SP10, double check in the "Agent Administration" UI.
N.B.: Use the SID/InstanceID to understand for each Agent On-the-fly by which Diagnostics Agent is has been created. Note that the Agent On-the-fly Instance ID includes the Logical hostname.

Frequently Asked Questions (FAQ)

Q: First actions in case an Agent On-the-fly does not seem to react on a Logical Hostname switch-over (from Physical/Virtual Host A to B)

• On Physical/Virtual Host A and Host B execute each time the following command to double check whether the Logical hostname move occurred as you expect at OS level and is seen by the SAP Host Agent.
  • For Windows:
    C:\Program Files\SAP\hostctrl\exe\saphostctrl.exe -function GetComputerSystem
  • For Unix:
    /usr/sap/hostctrl/exe/saphostctrl -function GetComputerSystem
• Additionally, perform on each Physical/Virtual Host (A and B) the ping command.
  • ping -a <Logical hostname>
• In case the SAP Host Agent reflects correctly the hostname topology proceed as follow:
  1. Go to solman_setup -> Managed System Configuration -> Host for Host A
     1. Navigate to step "Enter System Parameters" / field "Local exclusion filter" and write down the currently provided value
     2. Provide now a new filter (regular expression) to temporarily exlude the concerned Logical hostname
     3. Press "Save"
     4. Wait one minute
     5. In step "Enter System Parameters" / field "Local exclusion filter" provide again the initial value (you written down).
     6. Press "Save"
     7. Wait one minute
  2. Proceed as explained above also for Host B
  3. In case the problem persists (Agent On-the-fly not moving) kindly open a message on component SV-SMG-DIA-SRV-AGT.

• In case the SAP Host Agent does not see the Logical hostname as you expect, please open a message on component BC-CCM-HAG.

Q: What actions to take when saving a wrong value in the "Local exclusion filter"

1. In the "Local exclusion filter" field from step "Enter System Parameters" correct previously provided (exclusion) pattern
2. Press "Save"
3. Wait one minute
4. In case the previously defined pattern was wrong and had as a consequence that too many Agents On-the-fly were created, also remind to delete from LMDB the not relevant hostnames.
   1. Therefore start LMDB transaction
   2. In "Host" tab delete the no longer relevant hosts, which have been created by the outside discovery process run by the Agents On-the-fly