[ Teknoglot ]

I’ve been building a little SNMP Management Pack in the past few days to discover and monitor a bunch of PowerWare UPS’s, which turned out to take quite a lot more energy and time than expected. Mostly due to the facts that I am really bad with SNMP and how it works, I’ve never really looked into the inner working of building an SNMP management pack and also because we ran into a couple of errors preventing the discovery process to work alright.

To make it clear right away, this is not going to be a “Building an SNMP Management Pack Tutorial” since there’s plentiful good ones out there already, and to be extra helpful I’m gonna include a few links right away:

• SNMP Setup and Simple Custom SNMP Discovery – Pretty much the basics
• SNMP Management Pack Example: NetApp Management Pack – Part 4 actually, but has the links to the other parts
• Creating SNMP Probe Based Monitors – No custom discovery, but a good and simple guide to SNMP Probes

It’s the second, the NetApp one, I’ve used as a guide to building the UPS management pack since it goes through the process of building your own filtered discovery using SystemOID to identify your hardware-classes and then building the monitors on top of those.

Let’s get to it

When building the discovery of my hardware classes I ran into problems. The discovery simply did not work. At first I got some strange errors about “invalid queries”, something that turned out to be related to me reading two guides–seriously though, pick one guide that is closest to what you want to achieve and stick to it–and mixing up the XPathQuery variables. Silly me.
I got those errors to go away and I was able to get a few objects to my base-class, but none of the hardware classes who was populated through the return value of an SNMP OID got discovered.
The only error I got this time was the following:

Log Name:      Operations Manager
Source:        Health Service Modules
Date:          2010-09-02 11:19:12
Event ID:      11001
Task Category: None
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      CENSORED
Description:
Error sending an SNMP GET message to IP Address XX.XX.XX.XX, Community String:=CENSORED, Status 0x6c.

One or more workflows were affected by this.

Workflow name: CENSORED.MP.CLASS.DISCOVERY
Instance name: CENSORED_DEVICENAME
Instance ID: {5C7EFB30-D885-8843-0DD7-EA86B4FD2311}
Management group: CENSORED

<IsWriteAction>false</IsWriteAction>
<IP>$Config/IP$</IP>
<CommunityString>$Config/CommunityString$</CommunityString>
<Version>1</Version>
<SnmpVarBinds>
	<SnmpVarBind>
		<OID>1.3.6.1.4.1.534.1.1.1.0</OID>
		<Syntax>0</Syntax>
		<Value VariantType="8"></Value>
	</SnmpVarBind>
	<SnmpVarBind>
		<OID>1.3.6.1.4.1.534.1.1.2.0</OID>
		<Syntax>0</Syntax>
		<Value VariantType="8"></Value>
	</SnmpVarBind>
	<SnmpVarBind>
		<OID>1.3.6.1.4.1.534.1.1.3.0</OID>
		<Syntax>0</Syntax>
		<Value VariantType="8"></Value>
	</SnmpVarBind>
</SnmpVarBinds>

I’ve been looking for at way to evenly distribute agents between Gateway Servers (or Management Servers for that matter, but I’ll stick to GWs this time) for some time but haven’t really got to fixing it myself until now.

The situation is basically that we’re monitoring customers through gateway servers connected to our central Operations Manager environment. To have a bit of redundancy we always put two (or more) gateway servers per site (or customer, really) and they, in turn, talks to a couple of central management servers. I guess a drawing would be nice, but I have no Visio on this computer. The gateways are manually configured to talk to different management servers and have the others configured for fail-over (through powershell) and since we’re talking about no more than a few handfuls (say 20-ish) it’s not a problem handling it that way.

Agents, on the other hand, are a different matter. Even though we try to spread them out somewhat evenly at deployment between the gateway servers at each site we still end up looking at a 3:2 ratio after a while and since agents do not automatically fail-over between gateway servers we need a way to fix that too.
So I wrote a little powershell script that takes a bunch of gateway servers (or management servers) as parameters, gathers all connected agents, spreads the agents evenly between the servers and configures the others as fail-over servers while at it.

It’s all pretty crude, but it works and you can download it from here: DistributeAgents.ps1
Save it somewhere on disk and call it from the Operations Manager Shell like this:

C:\DistributeAgents.ps1 gateway01.customer.local,gateway02.customer.local,gateway03.customer.local

Yes, you should replace “C:\” with whatever path you decided to save the script to and “gatewayXX.customer.local” with a real servername.

Ok, I’m a powershell freshman and I’m pretty sure you could do this a prettier way, but here’s the script:

Param([array]$CSVServerList)

$arrServerObject = @()
$arrAgentObject = @()

foreach($Server in $CSVServerList)
{
	$arrServerObject += Get-ManagementServer | where {$_.Name -eq $Server}
	echo "Looking for $Server"
}
$ServerCount = $arrServerObject.Count
if ($ServerCount -gt 1)
{
	echo "Found $ServerCount management servers"
} else {
	echo "Found only 1 (or less) management servers. Aborting..."
	Exit
}

echo "Getting agents..."
foreach ($Server in $arrServerObject)
{
	$arrAgentObject += Get-Agent | where {$_.PrimaryManagementServerName -eq $Server.Name}
}
$AgentCount = $arrAgentObject.Count
if ($AgentCount -gt 1)
{
	echo "Found $AgentCount agents"
	Start-Sleep -m 200
} else {
	echo "Found only 1 (or less) agents. Aborting..."
	Exit
}
$i = 0
foreach ($Agent in $arrAgentObject)
{
	if ($i -ge $ServerCount)
	{
		$i = 0
	}
	$arrTemp = @($arrServerObject | Where-Object {$_ -ne $arrServerObject[$i]})
	# $FailoverServers = $arrTemp -join ","
	Set-ManagementServer -AgentManagedComputer: $Agent -PrimaryManagementServer: $arrServerObject[$i] -FailoverServer: $arrTemp

	$arrTemp = $null
	$i++
}

I have used it on a couple of occasions now and have only discovered a problem with an error when one of the servers don’t have any agents at all (probably a new one), but the script still works so I haven’t really dived into it.
Now, as with all scripts you download on the ‘net it’s up to you to test it in a lab before shooting wildly among your in-production systems. I really can’t give any warranties that it won’t FSU royally at your place.

This script has pretty much already been covered in my previous post about Changing or Replacing an Operations Manager Gateway Server.

This time I’ve basically put parameter support in it to make it easier to use.

Here’s the script anyway.

Param($OldGW,$NewGW)

$OldMS= Get-ManagementServer | where {$_.Name -eq $OldGW}
$NewMS = Get-ManagementServer | where {$_.Name -eq $NewGW}
$agents = Get-Agent | where {$_.PrimaryManagementServerName -eq $OldGW}
$agents = $agents
"Moving " + $agents.count + " agents from " + $OldMS.Name + " to " + $NewMS.Name
Start-Sleep -m 200
Set-ManagementServer -AgentManagedComputer: $agents -PrimaryManagementServer: $NewMS -FailoverServer: $OldMS

To use it, create a textfile called ChangeGW.ps1 and paste the code into it. Save the file somewhere neat (maybe C:\Scripts\) for easy access. If you don’t feel like copy/pasting, you can download the script here.

To use it, open the Operations Manager Command Shell and type:
C:\Scripts\ChangeGW.ps1 <old.gatewayserver.dns.name> <new.gatewayserver.dns.name>

For example:

C:\Scripts\ChangeGW.ps1 gwserver01.domainname.local gwserver02.domainname.local

Getting “ESENT Kerys are required to install this application” when you are trying to modify/change an agent installation?

This seems to be  most common on Windows 2008 and i guess it’s because of the AUC and the fact that opening the Control Panel isn’t running in administrative mode.

To work around this you need to run the msiexec command on the correct installation GUID from an administrative command prompt.

Besides running through the registry to find the GUID, one of the easier ways is this:

1. Open an administrative command prompt.
2. run wmic product
3. Locate your product by its name, the GUID (looks a bit like this {25097770-2B1F-49F6-AB9D-1C708B96262A}) directly after that is the one you want. Copy it.
4. run msiexec /i <PASTEYOURGUIDHERE>
5. Modify the agent as pleased

That’s pretty much it. Good luck.

Microsoft has released an update to the MSMQ (version 3) management pack.

System Center Pack for: Message Queuing 3.0
Version: 6.0.6615.0
Released on: 12/14/2009

Message Queuing (also known as MSMQ) is a server application that enables applications to communicate across heterogeneous networks and systems that may be temporarily offline or otherwise inaccessible. Instead of an application communicating with a service on another computer, it sends its information to Message Queuing, which sends the information to a Message Queuing service on the target computer where it is made available to the other application. Message Queuing provides guaranteed delivery, efficient routing, security, and priority based messaging.

Now, what’s really interesting is what you will find in the MP Guide under “Supported Configurations”.

The Message Queuing Management Pack for Operations Manager 2007 is designed to monitor Message Queuing version 3 only.

The Message Queuing Management Pack supports the following platforms:

· Windows Server 2003

· Windows XP

The Message Queuing Management Pack also supports monitoring clustered MSMQ components.

Text coloration is obviously added by me to highlight the interesting part.

Finally MSMQ monitoring seems to be cluster aware, which might mean that the home-made pack i did to have those (numerous) queues covered could be passed on to the scrap-heap. This is also confirmed under “Changes in This Update”.

The December 2009 update to this management pack includes the following change:

· Fixed a problem when working with an instance of MSMQ in a Cluster. The MP is now able to discover and monitor public and private queues in a cluster.

· Fixed a problem when discovering the local and cluster instance of MSMQ. The MP is now able to discover and monitor both instances.

The confusing double RunAs profiles seems to have been cleaned up too (you only have to worry about one now) as well as fixing some sloppy mistakes in the previous scripts (no Option Explicit? C’mon Microsoft! You write the best practices, try to stick to them.) and generally improving display and documentation.

Gonna import this to our staging environment today and let it roll during the holidays.

Cheers! Oh, and happy holidays!

Download and documentation:
http://www.microsoft.com/downloads/details.aspx?FamilyId=1D2B4398-8BC2-4A43-850C-852EBB0D983B&displaylang=en&displaylang=en

Here’s a little trouble-shooting guide for discovering Linux systems from OpsMgr R2 when getting the following error from the wizard:

<stdout>Generating certificate with hostname="COMPUTERNAME"

[/home/serviceb/TfsCoreWrkSpcRedhat/source/code/tools/scx_ssl_config/scxsslcert.cpp:198]

Failed to allocate resource of type random data: Failed to get random data - not enough entropy

</stdout><stderr>error: %post(scx-1.0.4-248.i386) scriptlet failed, exit status 1

</stderr><returnCode>1</returnCode>

<DataItem type="Microsoft.SSH.SSHCommandData" time="2009-08-05T11:15:01.5800358-04:00" sourceHealthServiceId="0EB1D6DA-202C-7FC5-3D46-BDBB9208547D"><SSHCommandData><stdout>Generating certificate with hostname="COMPUTERNAME"

[/home/serviceb/TfsCoreWrkSpcRedhat/source/code/tools/scx_ssl_config/scxsslcert.cpp:198]

Failed to allocate resource of type random data: Failed to get random data - not enough entropy

</stdout><stderr>error: %post(scx-1.0.4-248.i386) scriptlet failed, exit status 1

</stderr><returnCode>1</returnCode></SSHCommandData></DataItem>

But first, a little background on the actual “problem”. To generate the certificate, the entropy needs to be high enough to generate random data for the certificate creation. Without the certificate, the OpsMgr agent won’t be able to open up communications with the MS. So, what creates this entropy we need? Bluntly put, a selection of hardware components that are likely to produce non-predictable data. Like a keyboard, mouse and a monitor or videocard. Of course, there’s a lot more to it, but we really don’t need to know this. What we need to know is that there has to be a “bit bucket” of more than 256bytes of entropy for the certificate creation process to succeed. We also need to know that more enterprise-ish servers, like rack- or blade-servers tend to be void of things like directly attached keyboards, mouses and monitors that the linux kernel needs to be able to generate entropy. And herein lies the problem. If you have a new server that is not in full service (likely since we are trying to deploy the monitoring on it) which means that there’s not much random data flowing through the hardware and there’s no keyboard or mouse or monitor connected to it there is quite the risk that the system entropy is going to be very low. Of the linux systems that I have been deploying OpsMgr agents to, about half have failed because of “Not enough entropy”. So, here’s the steps I usually takes to ensure that discovery works. I use PuTTY to connect to the soon-to-be-monitored servers. This guide also assumes that you have SU rights on the system since all of these steps (except #1) needs it.

1. Check you current entropy

   cat /proc/sys/kernel/random/entropy_avail

   Is it less than, or close to, 256? It probably is. If you don’t feel like connecting a mouse and start wiggling it around—not really feasible in a data center—and see if the entropy increases, you can generate your own random data.

2. Generate you own random data.
   Be advised that this forced entropy will not be as random as the system-created on and thus not as secure. How much more insecure it is, I don’t know, and quite frankly I prefer to have my systems monitored yet slightly less secure than not monitored at all. Anyway, you can force your own random data by running:

   dd if=/dev/urandom of=~/.rnd bs=1 count=1024

   This creates a .rnd file with 1024B of random data that the certificate creation process will use instead of the system entropy if the file exists.

3. Uninstall and re-discover
   The first failed attempt of discovery will most likely leave a non-working agent installation that we have to remove. Otherwise we will just be stuck with an “Access Denied” error. Run:

   rpm –e scx

   Now, try to discover the system again.

4. Failed again?
   Try generating the certificate manually by running:

   /opt/microsoft/scx/bin/tools/scxsslconfig -f –v
   /opt/microsoft/scx/bin/tools/scxadmin –restart

   Retry discovery again.

5. Still fails?
   Uninstall the agent once more as instructed in step 3.

Stese steps have solved my problems 100% on both SUSE and RedHat and hopefully they will help you too.

Interestingely enough, these problems seems to be connected to some changes in the 2.6 kernel and basically everything that uses SSL-ish certificates will be affected. Even though the symptoms may be a bit more subtle, like time-outs and disconnects. For “headless” servers like those I usually to administer where the random data tend to be much lower, there’s even specialised hardware whose sole purpose is to generate random data, like the Entropy Key. I have also been told that new servers is likely to be equipped with entropy chipsets to make sure that there’s chaos enough to avoid these new-found oddities.

Sources:
http://social.technet.microsoft.com/Forums/en-US/crossplatformsles/thread/f94ec905-23ac-4444-b9f8-644fec3ae357

http://www.askrenzo.com/oracle/SCOM/SCOM_discovering_nodes.html

Microsoft has released an updated MP for SCCM SP2 (v6.0.6000.2, released on 10/28/2009) for OpsMgr R2.

The update basically contains support for x64 that was missin in the previous release.

The Configuration Manager 2007 SP2 Management Pack adds support for monitoring Configuration Manager 2007 SP2 in a 64-bit environment with Operations Manager 2007 R2 or Operations Manager 2007 SP1 with hotfix (KB971541) installed. This enables the Configuration Manager 2007 SP2 Management Pack to work with either the 32-bit or the 64-bit Operations Manager 2007 agent. Except for the 64-bit support, the other features and guidance for Configuration Manager 2007 Management Packs remain intact.

(coloration added by me)

Read more and download here:
http://www.microsoft.com/downloads/details.aspx?FamilyID=a8443173-46c2-4581-b3b8-ce67160f627b

This update hasn’t showed up in the MP Catalog yet, but the System Center Operations Manager 2007 R2 Cross Platform Update can be downloaded here.

Besides SUSE 11 support, here’s the short overview.

The System Center Operations Manager 2007 R2 Cross Platform Update adds fixes for a defunct process issue on Unix/Linux Servers, as well as, adds support for SUSE Linux Enterprise Server 11 (both 32-bit and 64-bit versions) and Solaris Zone support.
Feature Summary:
The System Center Operations Manager 2007 R2 Cross Platform Update supports the monitoring of Unix/Linux Servers including:

• Monitoring of SUSE Linux Enterprise Server 11 servers (both 32-bit and 64-bit versions)
• Support of Solaris Zones
• Fix for defunct Process issue
• The Cross Platform Agent may not discover soft partitions on Solaris systems. Therefore, the disk provider may be unloaded, and the Cross Platform Agent may stop collecting information from the system disks.
• The Cross Platform Agent may not restart after the AIX server reboots.

The latest versions of all the Operations Manager 2007 R2 Unix/Linux agents are included in this update.

Perfect timing, I must say, since I really need this today.

Update:
This is no small MP-update, which probably is the reason that we do not find it in the MP Catalog, but a ~250MB OpsMgr R2 Software Update. You need to run this on all Operations Manager Servers (RMS/MS, GW?) since it actually updates many of the agent Cross Platform binaries. It does add a new MP för SUSE 11 that you have to import from disk if you need it.

So, the installation goes somewhat like this:

1. Install the Software Update (pick the right Architecture) on all OpsMgr R2 Servers
2. Import the SUSE 11 MP if necessary
3. Re-discover your Unix/Linux machines.

Files updated in this update for R2:

• .\Microsoft.Enterprisemanagement.UI.Administration.dll (Version 6.1.7043.1)
• .\AgentManagement\UnixAgents\scx-1.0.4-248.aix.5.ppc.lpp.gz
• .\AgentManagement\UnixAgents\scx-1.0.4-248.aix.6.ppc.lpp.gz
• .\AgentManagement\UnixAgents\scx-1.0.4-248.hpux.11iv2.ia64.depot.Z
• .\AgentManagement\UnixAgents\scx-1.0.4-248.hpux.11iv2.parisc.depot.Z
• .\AgentManagement\UnixAgents\scx-1.0.4-248.hpux.11iv3.ia64.depot.Z
• .\AgentManagement\UnixAgents\scx-1.0.4-248.hpux.11iv3.parisc.depot.Z
• .\AgentManagement\UnixAgents\scx-1.0.4-248.rhel.4.x64.rpm
• .\AgentManagement\UnixAgents\scx-1.0.4-248.rhel.4.x86.rpm
• .\AgentManagement\UnixAgents\scx-1.0.4-248.rhel.5.x64.rpm
• .\AgentManagement\UnixAgents\scx-1.0.4-248.rhel.5.x86.rpm
• .\AgentManagement\UnixAgents\scx-1.0.4-248.sles.10.x64.rpm
• .\AgentManagement\UnixAgents\scx-1.0.4-248.sles.10.x86.rpm
• .\AgentManagement\UnixAgents\scx-1.0.4-248.sles.9.x86.rpm
• .\AgentManagement\UnixAgents\scx-1.0.4-248.solaris.10.sparc.pkg.Z
• .\AgentManagement\UnixAgents\scx-1.0.4-248.solaris.10.x86.pkg.Z
• .\AgentManagement\UnixAgents\scx-1.0.4-248.solaris.8.sparc.pkg.Z
• .\AgentManagement\UnixAgents\scx-1.0.4-248.solaris.9.sparc.pkg.Z

Files added:

• Microsoft.Linux.SLES.11.MP

All in all, the update contains the following fixes:

• KB969342
• KB973583
• Q954049
• Q956240

Microsoft released an updated MP (v6.1.7533.0, released on 10/8/2009) for monitoring the health the Operations Manager components.

Most significant updates, according to me, would seem to be:

Fixed an issue that was previously preventing all rules related to agentless exception monitoring from generating alerts.

Added the rule “Collects Opsmgr SDK Service\Client Connections” to collect the number of connected clients for a given management group. This data is shown in the view “Console and SDK Connection Count” under the folder “Operations Manager\Management Server Performance”.

Updated a number of monitors and rules to ensure that data is reported to the correct management group for multihomed agents.

Fixed the configuration of the rule “IIS Discovery Probe Module Execution Failure” to so that the parameter replacement will now work correctly for alert suppression and generating the details of the alert’s description.

The rest is mostly polishing, fine-tuning and complementary updates. Nothing really ground-breaking here, but still a welcome update.

Download at: http://www.microsoft.com/downloads/details.aspx?FamilyID=61365290-3c38-4004-b717-e90bb0f6c148

If you are looking into replacing an (or just switching to another primary) Operations Manager 2007 Gateway Server for any reason, there’s a little more to consider than just right-clicking the clients and selecting “Change Primary Management Server” in the Operations Console.
You could end up with agents not being able to connect to the Management Group at all due to a small problem with the order in which Operations Manager do things.

Here’s basically what happens:

• You tell Operations Manager to change Primary Management Server for AGENTX from GW1 to GW2.
• The SDK Service (i guess) tells GW1 that “You’re no longer the Primary Management Server for AGENTX”
• GW1 acknowledges this and stops talking to AGENTX. And I mean Completely stops talking to AGENTX.
• OpsMgr then tells GW2 to start accepting communication from AGENTX.
• OpsMgr tries to tell AGENTX that it should talk to GW2 since GW1 won’t listen.

Spotted the problem?
This modus operandi probably works when agents are on the same network and in the same domain where fail-over is sort of automatic. The problem we are facing now is that the server are telling the Gateway to stop accepting communications to and from the agent before the agent is notified that there is a new Gateway server to talk to. The agent will continue to talk to GW1 but will be completely ignored and you will probably start seeing events in the Operations Manager eventlog on GW1 with EventID 20000.

How do I get around this little feature then?

No matter if you found this article after running into the mentioned troubles or if you are googling ahead of time to be prepared, the fix is the same and consists of a few powershell scripts. These scripts are out there allready, but in different contexts, hence this post.

First step: Install the new Gateway

Documentation on this from Microsoft is good enough, but here’s the short version.

1. Verify name resolution to and from Gateway server and Management Server
2. Create certificate for the Gateway server
3. Approve the Gateway server
4. Install Gateway server
5. Import certificates on Windows system
6. Run MOMCertImport.exe on Gateway server to add the certificate into Gateway server configuration
7. Wait

The wait is for the gateway server to get all needed configuration from RMS and to download all neccesary management packs, run all the discovery scripts and so on. When the Operations Manager event log has calmed down a bit, move to step two.

Second step: Configure Agent Failover

Connect to an Operations Manager Command Shell. Any will do, as long as it’s connected to the correct Management Group.
Then run the following script:

$primaryGW= Get-ManagementServer | where {$_.Name -eq 'GW2.domain.local'}
$failoverGw = Get-ManagementServer | where {$_.Name -eq 'GW1.domain.local'}
$agents = Get-Agent | where {$_.primarymanagementservername -eq 'GW1.domain.local'}
Set-ManagementServer -AgentManagedComputer: $agents -PrimaryManagementServer: $primaryGW -FailoverServer: $failoverGw

Remember to change “GW1.domain.local” to you OLD Gateway servername and “GW2.domain.local” to your NEW Gateway servername.
If you don’t know powershell, this script basically configures all agents using the old Gateway to use the new one as primare, but keep the old one as a fail-over server. The Gateways will still get to know the changes before the agents, but since the old on is still listening to the agents (though, as the fail-over host) it will be able to tell them to go to the new one, GW2.