Frequently Asked Questions

Question 1

Where can I download the vSphere client?

Answer:

Where {VI Server} is the VMware Infrastructure server, navigate to:

https://{VI Server}

Question 2

Where can I download vSphere PowerCLI?

Answer:

This is available directly from VMware:

http://www.vmware.com

Question 3

Do I require vCenter in my enterprise to handle ESX/ESXi 4.0 hosts?

Answer:

No. You can use the direct connection method via SSH to monitor hosts without supporting VMware Infrastructure servers. For more information about enabling SSH on ESXi 4.0 or later hosts, refer to:

http://www.vm-help.com/esx40i/ESXi_enable_SSH.php

Question 4

When I try to monitor an object other than an object associated with the vCenter/host specified in my default VMware connection, I receive the error:

Object reference not set to an instance of an object

Answer:

This is related to the previous question.

During initial configuration of Argent for VMware,

the user is advised to specify a “default connection” in the Supervising Engine’s configuration.

The reason for this is to simplify management (instead of specifying explicit connections for each VMware object.

In the case of a user with a vCenter server, management of VMware objects is done through the server.

The server is aware of all objects associated with it.

However, there may be cases of a larger installation with multiple vCenter servers,

or isolated ESX/ESXi hosts, unassociated with any of the management infrastructure.

In this case, the user should explicitly specify the object’s connection attributes,

through the Node Properties in License Manager.

Question 5

Where can I find events to filter for in my VI Event Rules?

Answer:

An excellent reference is available from VMware. The VMware Infrastructure SDK Reference Guide, covering Data Object types, is available here:

http://www.vmware.mobi/support/developer/vc-sdk/visdk2xpubs/ReferenceGuide/vim.event.VmEvent.html

Question 6

What is unused provisioned space?

Answer:

When a virtual disk is created, it is provisioned, in one of three formats:

  • Thin: The size of the vmdk on the datastore is the amount of space used within the VM itself.

    As I/O occurs in the guest, vmkernel zeroes out space needed before any guest I/O is committed.

    In other words, the vmdk will grow as space is consumed, up to a maximum of the initial provision.

    Example: User thin provisions 50GB of space to a VM.

    After installation of Windows, there is a total of 6GB used.

    The size of the vmdk at this point is 6GB. As the VM uses up space,

    the size of the vmdk will continue to grow until it reaches 50GB.

  • Thick: The size of the vmdk on the datastore is the amount of space

    allocated when the the vmdk was initially provisioned.

    As I/O occurs on the guest, vmkernel zeroes out space needed before any guest I/O is committed.

    However, the vmdk will not grow as space is consumed, since the vmdk is already at its maximum size.

    Example: User thick provisions 50GB of space to a VM. After installation of Windows, there is a total of 6GB used.

    The size of the vmdk at this point is 50GB.

    As the VM uses up space, the size of the vmdk stays at 50GB, however any previously

    unused provisioned space must be zeroed out before guest I/O can commit.

  • Eagerzeroedthick: This provisioning format is similar to thick, with the following exceptions.

    During vmdk creation, all space is zeroed out.

    This provisioning strategy incurs more backend (datastore) I/O during vmdk creation,

    and less after (when compared to thin and thick formats)

    Example: Similar to thick format, however as space is used,

    there is no need to zero out the empty space first.

    Like the previous example, the vmdk starts at 50GB, and as the VM uses up space, it will stay at 50GB.

    The main difference between thick and eagerzeroedthick formats is the amount of backend storage I/O required.

    Thick provisioning incurs less I/O during vmdk creation, but as whitespace is written to (and zeroed out),

    I/O is more intensive. Eagerzeroedthick incurs more I/O during vmdk creation, and much less as whitespace is written to.

    Long story short: unused provisioned space is something a user will encounter when a vmdk is formatted using thin provisioning.

    It is the amount of space which the vmdk can grow to, but has not used yet. It is also referred to as whitespace.

    This also illustrates a point when monitoring performance on the host vs the guest.

    A host performance rule checks performance relative to the host,

    or how much of a resource is being consumed on the host.

    A guest performance rule checks the resources the guest is thinking it’s using.

    Example: We check a guest for CPU utilization, which is 80% at some given point in time. However, this may only be a small fraction of the host’s CPU utilization.