Snapshots and Automated Emails

A common problem in virtualization is snapshots. The name “snapshot” makes us (novice or otherwise!) think of a picture in time, which sometimes leads to the belief that the snapshot is “taken” and then stored somewhere, though that’s not how snapshots really work.

In reality, snapshots create a psuedo-consistent state of the virtual disk at that point in time. Subsequent writes in a snapshotted state are redirected to delta files. If you are performing an upgrade, a snapshot is helpful, allowing you to restore the prior system state if there are problems. After a few days, the snapshot loses its value as a restore becomes increasingly unlikely because you would lose the application changes as well. Snapshots also play a role in backups, where they are used temporarily to provide the psuedo-consistent state for the backup utility before the snapshot is deleted.

When a snapshot is deleted, that delta is applied to the base virtual disk(s), playing back through the transactions. Large snapshots take a long time to delete and affect system performance until the consolidation is complete. They can also affect the VM during normal operation as the delta file size increases.
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PowerShell Profile

In an earlier article, I described how to create a PowerShell Profile, specifically so that you could access PowerCLI snapins in the regular PowerShell or PowerShell ISE programs where you get tab completion and intellitype. However, it was buried in the midst of another article where it was hard to find.

The below PoSH will create a new profile if it doesn’t exist and add the VMware snapins, then it will open the profile file for editing. PowerShell and PowerShell ISE each have their own profile file, so run it in both if you need to.

Run the suggested commands below for the correct version of PowerCLI. If you have statements in your profile from a previous version of PowerCLI, clean them up by hand, or delete your profile and re-run the script to start with a blank profile. Note: This would wipe out any non-PowerCLI commands in your profile as well, such as those added by Chocolatey.

PowerCLI 6.5.1+

You don’t need a special profile anymore, there’s a new way to install that doesn’t require modifying the profile afterward. The instructions are simple. If you’ve set up one of the profiles below, I wrote up how to undo it.

PowerCLI 6.5 GA

Download. If you encounter errors after upgrading from a previous version, check the value of $env:PSModulePath. It should contain the path C:\Program Files (x86)\VMware\Infrastructure\PowerCLI\Modules rather than the older C:\Program Files (x86)\VMware\Infrastructure\vSphere PowerCLI\Modules. If it is incorrect, try a reboot, though the installer does not suggest one is required; that fixed the problem for me.

if (! (Test-Path $profile)) {
  New-Item -Path $profile -Type file -Force
}
''                                                        | Out-File -FilePath $profile -Append
'# Import PowerCLI modules'                               | Out-File -FilePath $profile -Append
'Get-Module -Name VMware* -ListAvailable | Import-Module' | Out-File -FilePath $profile -Append
notepad $profile

PowerCLI 6.0-6.3

if (! (Test-Path $profile)) {
    New-Item -Path $profile -Type file -Force
    'Add-PSSnapin VMware.VimAutomation.Core -ea "SilentlyContinue"' | Out-File -FilePath $profile -Append
    'Add-PSSnapin VMware.DeployAutomation -ea "SilentlyContinue"'   | Out-File -FilePath $profile -Append
    'Add-PSSnapin VMware.ImageBuilder -ea "SilentlyContinue"'       | Out-File -FilePath $profile -Append
    'Import-Module VMware.VimAutomation.Core'                       | Out-File -FilePath $profile -Append
    'Import-Module VMware.VimAutomation.Vds'                        | Out-File -FilePath $profile -Append
    'Import-Module VMware.VimAutomation.License'                    | Out-File -FilePath $profile -Append
}
notepad $profile

PowerCLI 5.5 and Below

if (! (Test-Path $profile)) {
    New-Item -Path $profile -Type file -Force
    'Add-PSSnapin VMware.VimAutomation.Core -ea "SilentlyContinue"'    | Out-File -FilePath $profile -Append
    'Add-PSSnapin VMware.VimAutomation.Vds -ea "SilentlyContinue"'     | Out-File -FilePath $profile -Append
    'Add-PSSnapin VMware.VimAutomation.License -ea "SilentlyContinue"' | Out-File -FilePath $profile -Append
    'Add-PSSnapin VMware.VimAutomation.Cloud -ea "SilentlyContinue"'   | Out-File -FilePath $profile -Append
    'Add-PSSnapin VMware.DeployAutomation -ea "SilentlyContinue"'      | Out-File -FilePath $profile -Append 
    'Add-PSSnapin VMware.ImageBuilder -ea "SilentlyContinue"'          | Out-File -FilePath $profile -Append
}
notepad $profile

Verify the profile contents are correct (this should preserve existing profiles, but check that new content didn’t merge at the end of the previous content). You can add any additional PoSH commands, such as aliases, to your profile, then save the file. Restart Powershell (ISE). Your startup will take a little longer now, but you end up with tab completion, intellitype AND PowerCLI. If you messed anything up, you should still have notepad open, just edit what’s needed and restart the PoSH shell till you get it right.

PowerCLI GitHub Repo – March 2014 Updates

In March, I created my PowerCLI GitHub Repo with just two cmdlets. By the end of March, I had many more cmdlets in the repo. Here are the updates:

PowerCLI-Administrator-Cmdlets

Via http://tenthirtyam.org/per-cluster-cpu-and-memory-utilization-and-capacity-metrics-with-powercli/ (@medavamshi):

  • Get-ClusterStats – A very detailed report on current Cluster resources and rough estimates of resources available after 1 or 2 cluster member failures. Useful in predicting failure scenarios as well as an eyeball view of capacity management.

Via http://hostilecoding.blogspot.com/ (@hostilecoding):

  • Edit-v10VMs – An alternative GUI to vCenter that can edit VMs with vHW 10. Useful for those without vCenter or who do not like the vSphere Web Client.

Via http://myvirtualcloud.net/?p=5924 (@StevenPoitras and @andreleibovici) are a pair of cmdlets useful for stress-testing your storage (and vCenter, if you’re not careful):

  • Clone-VM – Spin up a specified number of clones of the named VM, using VAAI by default.
  • Unclone-VM – Provide the name of the cloned VM and stop/delete all the clones.

Via http://pelicanohintsandtips.wordpress.com/2014/03/13/creating-multiple-virtual-machines-with-powercli/ is a single cmdlet for Template deployments

  • Deploy-Template – Use an existing Template and OSCustomizationSpec to deploy multiple instances of a Template into a specified Datacenter/Folder with sequential IPs.

PowerCLI-User-Cmdlets

Via http://www.shogan.co.uk/vmware/three-powercli-scripts-for-information-gathering-vms-hosts-etc/ (@shogan85) come three cmdlets that all have the option to output to CSV as well:

  • Get-VMHostBIOSInfo – Report on the Model and BIOS of all VMHosts attached to your connected vCenter.
  • Get-VMHostESXInfo – Report on the ESX(i) version and build of all VMHosts attached to your connected vCenter.
  • Get-VMHardwareInfo – Report on the vHW version of all VMs in a specified datacenter.

Via http://hostilecoding.blogspot.com/ (@hostilecoding):

PowerShell Trick via @alanrenouf

Alan Renouf gave a vBrownBag presentation on Advanced PowerCLI 5.5R2 last night. During the show, he showed an interesting bit of code:

$output = "" | Select VmName, PgName
$output.VmName = "value1"
$output.PgName = "value2"

This was intriguing to me. The “proper” way to create an object with attributes is to use New-Object and pipeline it through some Add-Member commands.

$output = New-Object PSObject |
Add-Member -PassThru NoteProperty VmName "value1" |
Add-Member -PassThru NoteProperty PgName "value2"

That creates an excessive, and somewhat unreadable, pipeline for objects with a long list of members, especially if a member’s name is long. It’s a pretty neat trick to make your code look pretty neat.

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PowerCLI GitHub Repo

Over the past couple of weeks, I’ve done a few PowerCLI posts, including creating some modules. To reduce the change of typos or older versions of files making it into my posts, I created a GitHub repo, https://github.com/rnelson0/powercli-modules/, that you can feel free to use. There are three modules:

  • Copy-Module – Based off the Hey Scripting Guy! module, this enhanced module allows us to load modules in the Global Modulepath (when run with admin privs) and overwrite existing modules.
  • PowerCLI-Administrator-Cmdlets – Cmdlets for an administrator. Generally speaking, these require read/write access. Example: Clone-VDPortgroup
  • PowerCLI-User-Cmdlets – Cmdlets for users. Ideal for read-only users. Example: Get-VMConsoles

Please use GitHub to send me pull requests for any bug fixes or report bugs. You can of course use comments as well.

Something I forgot to mention in my post on creating modules: If you use the snippets and fill out all the comments, Get-Help Your-Cmdlet will use that information and generate full help files for you. Very helpful!

PowerCLI GUI for VM Consoles

A few months ago, Dimitar Barfonchovski created a blog post on accessing the VM Console via PowerCLI, hosted on the PowerCLI Blog. Over the next few days, some cool enhancements came out focusing on a GUI for the featureset – which appear to have been lost to the great bitbucket in the sky, or I’d give some credit to them (if you know what I’m talking about, drop a link in the comments and I’ll update the article). I added a few enhancements of my own and ended up with a quick a dirty pastebin that would allow anyone to authenticate to any vCenter server and get a list of VMs they have access to.

I finally went back and combined this with last Friday’s post on creating a PowerCLI module. With a few tweaks we end up with an auto-import module and the cmdlet Get-VMConsoles. Any user can run this cmdlet. Upon connection to the specified vCenter server, you are prompted for authentication. After successfully authenticating, click Open VM Consoles and you are presented with a list of consoles available to your user. You can add a few filters, as I have done below. Ctrl-click to select the VMs you want to view and hit OK in the bottom right. Your consoles will open in your system’s browser in separate tabs.

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Creating a PowerCLI Module

A recent discussion on twitter about creating awesome PowerCLI output reminded me that the joy – and ease! – of creating your own PowerShell module needs to be spread.

If you do things the “right way”, by default you cannot click on a .ps1 file to open it. You need to launch PowerCLI (or launch PowerShell and import the PCLI snapins) and then import the file in whole or in part. Even if you create a new function that you want to use all the time, like a favorite “Get-SnapshotsIStupidlyLeftAroundForTooLong” function, it’s not there just by launching a PCLI/PoSH window. If you then want to modularize your PoSH into discrete parts and re-use them with other functions, you quickly end up with a very large .ps1 file that you import every time to so that all your functions are there. But they’re still functions, not cmdlets.

You don’t need to be a developer to create your own modules. Microsoft has some VERY in-depth documentation on modules that everyone should use. We’ll stick to the highlights as this is PowerShell Modules For Sysadmins. We’ll skip all the stuff about signing your code and making binary modules and focus on what most of us need every day – a way to modularize our PoSH code and streamline our ability to use it. I do encourage you to come back and look at code signing later if you plan to get serious about PoSH.

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