All about refreshers ...

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