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Disable LUN During ESXi Installation

04.17.2012 by William Lam // 14 Comments

For many of us who worked with classic ESX back in the day, can recall one of the scariest thing during an install/re-install or upgrade of an ESX host that had SAN attached storage, was the potential risk of accidentally installing ESX onto one of the LUNs that housed our Virtual Machines. As a precaution, most vSphere administrators would ask their Storage administrators to either disable/unplug the ports on the switch or temporarily mask away the LUNs at the array during an install or upgrade.

Another trick that gained popularity due to it's simplicity was unloading the HBA drivers before the installation of ESX began and this was usually done as part of the %pre section of a kickstart installation. This would ensure that your SAN LUNs would not be visible during the installation and it was much faster than involving your Storage administrators. With the release of ESXi, this trick no longer works. Though, there have been several enhancements in the ESXi kickstart to allow you to specify specific types of disks during installation, however, it is possible that you could still see your SAN LUNs during the installation.

I know the question about disabling the HBA drivers for ESXi comes up pretty frequently and I just assumed it was not possible. A recent question on the same topic in our internal Socicalcast site got me thinking. With some research and testing, I found a way to do this by leveraging LUN masking at the ESXi host level using ESXCLI. My initial thought was to mask based on the HBA adapter (C:*T:*L:*) and this would still be somewhat manual depending on your various host configurations.

The above solution was not ideal, but with the help from some of our VMware GSS engineers (Paudie/Daniel), they mentioned that you could create claim rules based on variety of criteria, one of which is the transport type. This meant that I could create a claim rule to mask all LUNs that had one of the following supported transport type: block, fc, iscsi, iscsivendor, ide, sas, sata, usb, parallel or unknown.

Here are the following commands to run if you wish to create a claim rule to mask away all LUNs that are FC based:

esxcli storage core claimrule add -r 2012 -P MASK_PATH -t transport -R fc
esxcli storage core claimrule load
esxcli storage core claiming unclaim -t plugin -P NMP
esxcli storage core claimrule run

Another option that was mentioned by Paudie, was that you could also mask based on a particular driver, such as the Emulex driver (lpfc680). To see the type of driver a particular adapter is being supported by, you can run the following ESXCLI command:

esxcli storage core adapter list

Here is a screenshot of a sample output:

For more details about creating claim rules be sure to use the --help option or take a look at the ESXCLI documentation starting on pg 88 here.

Now this is great, but how do we go about automating this a bit further? Since the claim rules would still need to be executed by a user before starting an ESXi installation and also removed after the post-installation. I started doing some testing with creating a customized ESXi 5 ISO that would "auto-magically" create the proper claim rules and remove them afterwards and with some trial/error, I was able to get it working.

The process is exactly the same as laid out in an earlier article How to Create Bootable ESXi 5 ISO & Specifying Kernel Boot Option, but instead of tweaking the kernelopt in the boot.cfg, we will just be appending a custom mask.tgz file that contains our "auto-magic" claim rule script. Here is what the script looks like:

#!/bin/ash

localcli storage core claimrule add -r 2012 -P MASK_PATH -t transport -R fc
localcli storage core claimrule load
localcli storage core claiming unclaim -t plugin -P NMP
localcli storage core claimrule run

cat >> /etc/rc.local << __CLEANUP_MASKING__
localcli storage core claimrule remove -r 2012
__CLEANUP_MASKING__

cat > /etc/init.d/maskcleanup << __CLEANUP_MASKING__
sed -i 's/localcli.*//g' /etc/rc.local
rm -f /etc/init.d/maskcleanup
__CLEANUP_MASKING__

chmod +x /etc/init.d/maskcleanup

The script above will create a claim rule to mask all FC LUNs before the installation of ESXi starts, this ensure that the FC LUNs will not be visible during the installation. It will also append a claim rule remove to /etc/rc.local which will actually execute before the installation is complete, but does note take effect since it is not loaded. This ensures the claim rule is automatically removed before rebooting and we also create a simple init.d script to clean up this entry upon first boot up. All said and done, you will not be able to see your FC LUNs during the installation but they will show up after the first reboot.

Disclaimer: Please ensure you do proper testing in a lab environment before using in Production.

To create the custom mask.tgz file, you will need to follow the steps below and then take the mask.tgz file and follow the article above in creating a bootable ESXi 5 ISO.

  1. Create the following directory: mkdir -p test/etc/rc.local.d
  2. Change into the "test/etc/rc.local.d" directory and create a script called mask.sh and copy the above lines into the script
  3. Set the execute permission on the script chmod +x mask.sh
  4. Change back into the root of the "test" director and run the following command: tar cvf mask.tgz *
  5. Update the boot.cfg as noted in the article and append mask.tgzto the module list.

Once you create your customized ESXi 5 ISO, you can just boot it up and either perform a clean installation or an upgrade without having to worry about SAN LUNs being seen by the installer. Though these steps are specific to ESXi 5, they should also work with ESXi 4.x (ESXCLI syntax may need to be changed), but please do verify before using in a production environment.

You can easily leverage this in a kickstart deployment by adding the claim rule creation in the %pre section and then adding claim rule removal in the %post to ensure that upon first boot up, everything is ready to go. Take a look at this article for more details for kickstart tips/tricks in ESXi 5.

Categories // Automation, ESXi Tags // esxi 5, esxi4.1, kickstart, ks.cfg, LUN

Extracting SSL Thumbprint from ESXi

04.15.2012 by William Lam // 13 Comments

While browsing the VMTN forums earlier this week, I noticed an interesting request from a user who was trying to compile an inventory of the SHA1 Thumbprints for all his ESXi hosts. The challenge the user had, was that he was capturing this information manually by "looking" at the DCUI screen which is where the SHA1 Thumbprint for an ESXi host is displayed by default.

As you might have guessed, this can be very tedious and error prone by copying down this very long string by just looking at the screen. Even if you do not make a mistake copying this long string, I bet your eyes will eventually give out. Luckily, there are a few ways to retrieve this information and I will show you some methods to help automate this across all of your ESXi hosts.

UPDATE (05/22/16) - Here's how you can extract SSL Thumbprint using PowerShell

Option 1 - Retrieve SSL Thumbprint using the DCUI as shown above, this is going to be the most manual method.

Option 2 - If you have remote SSH or direct console access to ESXi Shell, you can login to your ESXi host and using openssl utility, you can retrieve the SSL Thumbprint which you can then use or copy off to a remote host.

openssl x509 -in /etc/vmware/ssl/rui.crt -fingerprint -sha1 -noout

Option 3 - You can remotely retrieve the SSL Thumbprint by leveraging just the openssl utility and you do not even need to login to the ESXi host. This not only allows you to retrieve the SSL Thumbprint from a centralized location, but you can easily automate this across all your hosts.

echo -n | openssl s_client -connect 172.30.0.252:443 2>/dev/null | openssl x509 -noout -fingerprint -sha1

Using Option 3, you can easily wrap this in a simple "for" loop to iterate through all your ESXi hosts as long as you have either the hostname/IP Address. Here is a simple shell script that you can use to iterate through all your ESXi hosts to extract the SSL Thumbprint.

In the script above, I have a list of three ESXi hosts and it is simply going through each host and executing the two commands to extract the SSL Thumbprint and displaying it on the screen.

Option 4 - You can also retrieve the SSL Thumbprint using the vSphere API, but the property is only displayed when it is connected to a vCenter Server. There is a property on the ESXi host called sslThumbprint that is populated when querying against the vCenter Server that is managing the ESXi host. You can use the vSphere Health Check script which captures this and other useful information about your vSphere infrastructure.

As you can see, there are several options on obtaining the SSL Thumbprint for an ESXi host, you definitely do not have to manually read it off the DCUI screen. Automation FTW again! 🙂

Categories // Automation, ESXi Tags // esxi 5, esxi4, PowerCLI, powershell, sha1, ssl certificate, thumbprint

Auditing vMotion Migrations

04.12.2012 by William Lam // 3 Comments

I saw an interesting question this week about auditing vMotion events and the number of times a VM has migrated to a particular ESX(i) host for license compliance. You can view this information using the Task/Events in your vCenter Server but you can also extract out the various types of events using the EventManager in the vSphere API. You will be able to go as far back in time as your vCenter Server's database retention policy allows you to. We will be searching for the VmMigratedEvent Event which will include variety of information including the source and destination host for the VM. The destination host will only be populated upon a successful vMotion.

Of course I had to write a script to help automate this, so here is a vSphere SDK for Perl script called getNumberOfvMotions.pl that accepts the name of an existing VM and will return the number of vMotions that has been performed on the VM as well as the list of destination hosts and the number of times it has migrated to those hosts. You will need a system that has the vCLI installed or you can you use vMA.

Note:  If you want to look at past vMotion for a VM that no longer exists, this is still possible, but you will need to parse the "message" within the Event as you can no longer look up that VM object in vCenter.

Here is an example of the script running:

You can easily modify the script to audit all VM's in your environment or just use a simple "for" loop to go through a set of VM's you are interested in, but I will leave that as an exercise for you.

Categories // Automation, vSphere Tags // event, VmMigratedEvent, vmotion, vSphere, vSphere API, vsphere sdk for perl

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Author

William Lam is a Senior Staff Solution Architect working in the VMware Cloud team within the Cloud Infrastructure Business Group (CIBG) at VMware. He focuses on Cloud Native technologies, Automation, Integration and Operation for the VMware Cloud based Software Defined Datacenters (SDDC)

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