Information Technology Reference
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Failure Interval: If vSphere HA doesn't detect any VMware Tools heartbeats, disk I/O, or
network I/O within this time frame, it will consider the VM failed and will restart the VM.
Minimum Uptime: vSphere will wait for a set amount of time after the VM has been pow-
ered on before starting to monitor VMware Tools heartbeats. This is to ensure that the OS
has time to boot and heartbeats stabilize.
Maximum Failures: This is the maximum number of times vSphere HA will restart a VM
within the specii ed failure window. If Maximum Failures is set at 3 and a VM is marked
as failed a fourth time within the specii ed failure window, it will not be automatically
restarted. This prevents vSphere HA from endlessly restarting problematic VMs.
Failure Window: vSphere will restart the VM only a maximum number of times (Maximum
Failures) within this time frame. If more failures occur within this period of time, the VM is
not restarted.
If these predei ned options aren't sufi cient, you can select Custom and specify your own val-
ues for Failure Interval, Minimum Uptime, Maximum Per-VM Resets (Maximum Failures), and
Maximum Resets Time Window (Failure Window). Figure 7.24 shows a custom VM Monitoring
sensitivity coni guration.
Figure 7.24
h e Custom option
provides specifi c
control over how
vSphere HA moni-
tors VMs for guest
OS failure.
As with other areas of vSphere HA, you also have the option of coni guring per-VM monitor-
ing settings. This allows you, on a per-VM basis, to enable or disable VM monitoring and appli-
cation monitoring sensitivity levels. Thus, if you need VM monitoring for only a few VMs, you
can dei ne a default cluster setting and then coni gure the exceptions accordingly.
The last coni guration area for vSphere HA is datastore heartbeating.
Setting vSphere High Availability Datastore Heartbeating
Datastore heartbeating is part of the functionality found in vSphere HA from vSphere 5.0. By
communicating through shared datastores when the ESXi management network is not available,
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