Yellow Bricks

by Duncan Epping

Server

VM Report

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I had some spare time on my hands so I decided to add some useful stuff to the VM Reporting powershell script that was posted on this blog. This is what I ended up with, there’s still room for improvement like snapshot information and scsi controller info…


Get-VIServer -Server 192.168.1.1 -User admin -Password admin

$Report = @()

get-vm | % {
$vm = Get-View $_.ID
$ReportRow = "" | Select-Object VMName, Hostname, OS, IPAddress, VMState, TotalCPU, TotalMemory, MemoryUsage, TotalNics, ToolsStatus, ToolsVersion, MemoryLimit, MemoryReservation
$ReportRow.VMName = $vm.Name
$ReportRow.HostName = $vm.guest.hostname
$ReportRow.OS = $vm.guest.guestFullName
$ReportRow.IPAddress = $vm.guest.ipAddress
$ReportRow.VMState = $vm.summary.runtime.powerState
$ReportRow.TotalCPU = $vm.summary.config.numcpu
$ReportRow.TotalMemory = $vm.summary.config.memorysizemb
$ReportRow.MemoryUsage = $vm.summary.quickStats.guestMemoryUsage
$ReportRow.TotalNics = $vm.summary.config.numEthernetCards
$ReportRow.ToolsStatus = $vm.guest.toolsstatus
$ReportRow.ToolsVersion = $vm.config.tools.toolsversion
$ReportRow.MemoryLimit = $vm.resourceconfig.memoryallocation.limit
$ReportRow.MemoryReservation = $vm.resourceconfig.memoryallocation.reservation
$Report += $ReportRow
}
$Report | Export-CSV c:\export.csv

Scripted install

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A while back I wrote a scripted install aka “cfg” file, and I just noticed I never published it. Check it out, it might be useful in one way or another. It also available for download here!

Especially changing the amount of active nics in a team can be useful(I’ve commented this out again, as of ESX 3.5 U3 this isn’t necessary anymore. Enabling vmotion via the vimsh command is still valid. [Read more…] about Scripted install

Deleting snapshots when everything else failse…

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The common mis perception of the term “snapshot”, related to VMware, can cause huge problems. I’ve spend a lot of time the last years solving snapshot problems. For once and for all, a snapshot isn’t a static situation like a clone is. A snapshot can best be compared to a redo log, although technically it isn’t because it’s just a bitmap of disk sectors that changed. When you create a snapshot you only create a small “differences” file (*.delta.vmdk) which will contain all the differences until you delete or revert. Please remember reverting(go to) doesn’t delete the differences file! And this file can grow very fast depending on how many changes are made on the disk.

Another thing that people don’t know is the way “delete all” works, but I’ve already outlined that a while ago in a blog.

When you’ve got for instance a 10 levels deep nested snapshot tree with a very large last snapshot it would almost be impossible to press delete all because it will take up a lot of disk space. It would consume a lot of time doing a “delete” for every snapshot, and still it would always take up additional diskspace.

Another way to remove the snapshot is just by cloning the VM to another Datastore. This way you don’t need the extra disk space on the same datastore, and it might be a good moment to consider re-loadbalancing your lun’s again. [Read more…] about Deleting snapshots when everything else failse…

Virtual Machine tweaks for a better performance

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Over the last couple of months I gathered the following tweaks for a better performance insight the virtual machine, besides disabling / uninstalling useless services and devices:

  1. Disable the pre-logon screensaver:
    Open Regedit
    HKEY_USERS\.DEFAULT\Control Panel\Desktop
    Change the value of “ScreenSaveActive” to 0.
  2. Disable updates of the last access time attribute for your NTFS filesystem, especially for i/o intensive vm’s this is a real boost:
    Open CMD
    fsutil behavior set disablelastaccess 1
  3. Disable all visual effects:
    Properties on your desktop
    Appearance -> Effects
    Disable all options.
  4. Disable mouse pointer shadow:
    Control Panel -> Mouse
    Click on the tab “pointers” and switch “enable pointer shadow” off.

So if you’ve got an addition, please post it and I’ll keep updating this blog post!

Scalable Storage Performance PDF

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I was just reading up on the PDF’s I gathered over the last couple of weeks and found the Scalable Storage Performance pdf extremely useful. It contains a good explanation about the queue depth setting and much more….

To reduce latency, ensure that the sum of active commands from all virtual machines does not consistently exceed the LUN queue depth. Either increase the queue depth as shown in the VMware Infrastructure 3 Fibre Channel SAN Configuration Guide (the maximum recommended queue depth is 64) or move the virtual disks of some virtual machines to a different VMFS volume. You can find the guide at
http://www.vmware.com/pdf/vi3_35/esx_3/r35/vi3_35_25_san_cfg.pdf.
Also make sure to set the Disk.SchedNumReqOutstanding parameter to the same value as the queue depth. If this parameter is given a higher value than the queue depth, it is still capped at the queue depth. However, if this parameter is given a lower value than the queue depth, only that many outstanding commands are issued from the ESX kernel to the LUN from all virtual machines. The Disk.SchedNumReqOutstanding setting has no effect when there is only one virtual machine issuing I/O to the LUN.