Tag Archives: AHV

How to view a VMs Active Working Set in PRISM

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Knowing a Virtual Machines Active Working Set is critical to ensuring all flash performance in any hybrid storage solution (Flash + SAS or SATA).

Because this is so critical, Nutanix has tracked this information for a long time via the hidden 2009 page. However as this information being available has proven to be so popular, it was included in PRISM in the latest release of Nutanix Acropolis Base Version 4.5.

The working set size for a virtual machines active working set can be viewed on a per vdisk basis across all supported hypervisors including ESXi, Hyper-V, KVM and the Acropolis Hypervisor (AHV).

To view this information, from the “Home” screen of PRISM, select the “VM” as shown below:

Note: The following screen shots were taken from an environment running Acropolis Base Version 4.5 and Acropolis Hypervisor 20150921 but the same process is applicable to any hypervisor.

PRISMVMmenu

Next highlight the Virtual Machine you wish to view details on, In the example below VM “Jetstress01” has been highlighted.VMlist

Below the above section you will see the VM summary as shown below. To view the working set size, Select “Virtual Disks” then the “Additional Stats” option which will show the following display:WorkingSetSizeAdditionalDetailsAs we can see the following information is displayed on a per vdisk granularity:

  1. Read / Write Latency
  2. Total IOPS
  3. Random IO percentage
  4. Read Throughput from Extent Cache / SSD and HDD
  5. Read Working set size
  6. Write Working set size
  7. Union Working set size

With the above information it is easy to calculate what node type and SSD capacity is most suitable for the virtual machine. This is something I would recommend customers running business critical applications check out.

If the “Read Source HDD” is showing frequent throughput and performance is lower than desired, moving the VM to a node with a larger SSD capacity will help performance. Alternatively if there are no nodes with a larger SSD tier, enabling in-line compression and/or Erasure Coding can help increase the effective SSD tier capacity and allow a larger working set size to be served from SSD.

If compression and EC-X are enabled and the SSD tier is still insufficient, additional nodes with larger SSD tier can be non disruptively added to the cluster and the virtual machine/s migrated regardless of hypervisor.

Acropolis Base Version 4.5 adds a lot of enhancements such as this so I recommend customers perform the one click upgrade and start exploring and utilizing this additional information.

Uploading ISOs & VM Images to Acropolis Hypervisor (AHV)

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A common question is how do I upload an ISO or Virtual machine image to the Acropolis Hypervisor, well in NOS 4.5 this task just got radically simpler.

The below shows the “Home” screen in PRISM UI. As we can see in the top left we are running the Acropolis Hypervisor (AHV) version 20150616.

By clicking the gear wheel at the top right, we can then access the “Image Configuration” menu.PRISMHomeImageService

The “Image configuration” menu is a quick and easy way to upload ISOs and Virtual Machine images to Acropolis.

Below we can see its a very simple process, simply give the Image a name along with annotation, select from a drop-down list the Image type, being ISO or Disk (RAW format, .img) and then select the image source, either from a URL or by uploading a file from your machine.

CreateImage

Once you have selected your ISO or Disk, hit save and the image will be uploaded and the status of the upload will be shown as per the below:

CreateImageUploading

Once its completed, PRISM shows the following Summary:

ImageConfigurationSuccess

Now when you create a new VM, you will be able to select “Clone from Image Service” and select the ISO Image from a drop-down list. How simple is that!

CDROMimageservice

Simple as that! Now you can boot your VM and start using the ISO. The same process can also be used to upload VM disk images.

Acropolis Hypervisor (AHV) & non-uniform node CPU generations

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For those of you familiar with VMware vSphere’s Enhanced vMotion Compatibility (EVC) feature, you might be wondering how non-uniform CPU generations are handled in an Acropolis Hypervisor (AHV) environment.

Well, as with most things Nutanix, the answer is simple.

NOS 4.5 automatically detects and configures the lowest common CPU generation as the baseline on a per cluster basis.

The following diagram shows how it works:

AHVEVC2

As we can see, we have a four node Acropolis cluster with 3 different CPU generations. Acropolis detects Sandy Bridge as the lowest common denominator and ensures VMs on all nodes are only exposed the Sandy Bridge CPU capabilities.

This ensures Live migration capabilities are maintained across the cluster.

Note: As with vSphere’s EVC, VMs still benefit from higher clock rates and performance from newer generation CPUs, they just don’t have all CPU capabilities exposed, so don’t be fooled into thinking your newer/faster CPUs are wasted in a mixed environment.