vCenter has some great inbuilt alarms which can trigger alerts via email or SNMP to the IT administrator I have seen quite a few environments, where alarms haven’t been configured! The obvious question is, is this due to lack of knowledge or do the administrators really check every item manually within vSphere? My guess is the earlier.
With this in mind, I thought I would go over the basic settings and then also what alarms/alerts I generally put in place along with some rational over the triggers.
The first thing we have to do is configure vCentre to send out email and SNMP alerts. Go to Home > vCenter Servers Settings or to Top Menu Bar > Administration > vCenter Server Settings
Select Mail from the left hand side and enter your SMTP Server details. Note that VMware does not support email authentication, so if you are using an Exchange 2003/2007/2010 I recommend you create a new receive connector called ‘vmware’.
Select SNMP from the left hand side and enter either the IP Address or DNS Name of your SNMP Server along with the community string needed to validate if any different from ‘public’
If you need the MIBS (Management Information Base) these can found at %ProgramFiles%VMwareInfrastructureVirtualCenter ServerMIBS if the default installation path has been used.
Alarms can be configured at a few different levels which are:
Root these alarms will encompass Datacentre, Cluster, ESXi Hosts, Resource Pools and VM’s
Datacentre these alarms will encompass Cluster, ESXi Hosts, Resource Pools and VM’s
Cluster these alarms will encompass ESXi Hosts, Resource Pools and VM’s
ESXi Hosts these alarms will encompass Resource Pools and VM’s
Resouce Pools these alarms will encompass the VM’s that reside within them.
VM these alarms are only specific to the virtual machine
Generally speaking, nearly all the alarms which I create are done at the root level which means that whatever actions are performed by the vCentre administrator, they should be covered.
vCentre allows you to configure actions for alarms based around set criteria. When the alarm is triggered it can be configured to alert once or repeat
When the alarm triggers, it will do so when it enters a warning state e.g. Datastore Disk Usage Is Above 90% and then again when it hits a critical state e.g. Datastore Disk Usage Is Above 95%
So following this through, alarms can be triggered by the following events:
Normal Condition > Warning Condition
Warning Condition > Critical Condition
Critical Condition > Warning Condition
Warning Condition > Normal Condition
Alarms can be triggered if they meet ‘any’ of the conditions or ‘all’ the conditions you have set.
If you are a savy VMware Administrator you may ask the storage team for a 2TB LUN, but you only really need 1TB. So you provision a datastore at 50% capacity so you want to create a warning alarm when it reaches 75% provisioned and then critical at 90% provisioned, so you know when to ask for some extra space from the storage team.
With this in mind, imagine you had a single alarm which covered both Datastore Disk Usage (%) and Datastore Disk Provisioned (%). However, I would always recommend using ‘trigger if any of the conditions are satisfied unless you have a compelling reason not to do so.