All about refreshers ...

Cheng Wei — Thu, 02 Oct 2008 02:19:00 GMT

If you have been using VMM for a while, you’ve probably figured out that we use various “refreshers” to pull data from the hosts and VMs that we manage. When deploying VMM in various sized environments, depending on the perf/scale requirements, you might need to tweak the refresher schedule to achieve the best performance.

So, to help you understand what’s happening “under the hood”, here are the refreshers we use in SCVMM 2008 product. Please note, that not all refreshers are customizable.

Host Refresher: Runs every 30mins on every host (with time lags) and updates host properties. It also updates disk/SAN and host network (NIC / virtual switch) information. It does not check any VM related properties or perf counters on hosts. Can be manually triggered on the UI or through cmdlet.

VM Refreshers: Two types

VM Heavy Refresher: Runs every 30mins on every Host and also runs whenever a VM is clicked on (or when you call refresh-vm cmdlet). It updates all VM properties, resource pools, clustering information for this VM and snapshots. But it does not update VM performance counter info.

VM Light Refresher: Runs every 2mins on every Host that is currently in the VMM database. This refresher does the following:

- Checks the host state (to see if the agent is running or the agent is down) and virtualization software status

- Syncs the state of a VM

- Marks VMs as missing

- Imports new VMs created outside of VMM (When VMM detects a new VM created on the virtualization platform, we import it into VMM and kick off the heavy refresher for the new VMs)

Cluster Refresher: Runs every 30mins and refreshes all cluster properties (including bringing in newly added nodes or taking our removed nodes). Can be manually triggered on the UI or through cmdlet.

Library Refresher: Runs on user configurable schedule (increment by 1 hour interval and can be turned off completely) and updates the library shares info and library objects. Can be manually triggered on the UI or through cmdlet.

Perf Refresher: Runs every 9 minutes on a host or whenever there is any state changing operation on the VM (i.e. start/stop/save/etc.). It collects perf counter information of both the host and all the VM’s on a given host.

VirtualCenter Refresher: Runs every 30mins and refreshes VC properties, ESX hosts and resource pools that are managed by this VC. Can be manually triggered on the UI or through cmdlet.

User Role Refresher: Runs every 30mins and updates user role properties.

PRO Tip Refresher: Runs every 30secs. It looks for PRO specific alerts in OpsMgr and reconciles the PRO tips in our DB against the data that is brought back from OpsMgr. This refresher cannot be manually triggered.

Thanks for reading and hope this is useful,

Cheng

Intelligent Placement in SCVMM 2008

Cheng Wei — Wed, 14 May 2008 05:17:00 GMT

Intelligent Placement feature is one of the unique functionalities that you will only find in Microsoft virtualization technology offerings. In VMM 2008, we continue expanding support of our intelligent placement functionality into those newly supported host and VM platforms, including VMware environment. So, when you use SCVMM 2008 to manage your VMware environment, not only will you get a "single-pane-of-glass" management tool, you'll also get this advanced feature for your ESX hosts that does not exist in VMware.

Let me explain what Intelligent Placement is and how it works:

What is Intelligent Placement?

How Intelligent Placement works?

Intelligent Placement is a capacity planning function. We take various performance (CPU, memory, disk, etc.) data collected from the VM and the host where the VM runs, feed that into our modeling module, mix it with user-defined placement perference (priority), and at the end, for a given VM, we generate a set of ratings for hosts that are managed by VMM.

How is the host rating calculated?

The top three things that you must know about Intelligent Placement in SCVMM 2008:

Understanding your placement requirements

Do you want to consolidate your servers? or you want to load balance your workloads?
Characteristics of your new workloads (CPU-bound or disk-bound or memory-bound or network-bound)
We profile your existing VM workloads

Scoping your hosts

Once you defined your rating criteria based on your workload requirements, VMM will calculate the ratings for all your available hosts.
But, is the highest rating host you wanted for placement? What if you need a host in a specific zone (dev / test / production)? What if you need a host that is capable of quick migration or VMotion?
Hence, the next question you should consider is what zone (location, groups, domains, etc.) you want your workload to be placed.

Over-Committing

SCVMM 2008 allows you to over-committing CPU resouces, but it does not allow over-committing memory resources.
When planning for your workload placement, considerations need to be made in balancing VM consolidation as well as risks in peaking out your physical resource capacity (by placing more in your reserve or paying for HA solutions).

Thanks for reading,

Cheng

Cheng's Random Thoughts on System Management : Intelligent Placement

All about refreshers ...

Intelligent Placement in SCVMM 2008