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rsaha
Enthusiast
Enthusiast

Does HA detect guestOS failures

As I know VMware HA is focused on hardware failure,not on operating system or software failure.(mentioned in vmware_ha_wp.pdf)

At the same time I found following feature as mentioned in VMware-High-Availability-DS-EN.pdf

Automatic detection of operating system failures ->>

VMware HA detects operating system failures within virtual machines by monitoring heartbeat information. If a failure is detected, the affected virtual machine is automatically restarted on the server.

Above two stmt are contradictory.Can you please explain it.

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weinstein5
Immortal
Immortal

By default HA does not monitor individual VMs - it is a feature that can be enabled. When enabled it will look for the heartbeat that VMware Tools sends and if the heartbeat is not detected the VM will restart - you can set the sensitibity to which HA will respond to the loss of heartbeat so the VM does not restart just beacuse the machine is overloaded -

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arturka
Expert
Expert

Hi,

Like weinstein5 says, HA can detect when guest OS fails and can restart VM automatically, but be aware that this feature us related only to OS not for APP, this feature it isn't APP aware - just for your information. I saw many discussion on forums about that feature and a lot of confusion around it. There are some third party tools which leverage that HA feature and are APP aware (it was something from Symantec - forgot a name of the product)

That feature relay on VMware tool heartbeat but not only, also on CPU activity, LAN and SAN traffic, if they are below certain threshold then HA consider VM as a faulty and try to restart it.

VCDX77 My blog - http://vmwaremine.com
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rsaha
Enthusiast
Enthusiast

Thanks guys.Till I have confusion.What type of OS failure can it detect?

Say,my OS crashed...natuarally it won't get heartbeat from that VMs(am I right?).

Then will HA comes in picture?

Can you please give some example.

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Mouhamad
Expert
Expert

Hello there,

When your OS crashes, your VMware tools will not be responding. This is when your HA will intiate a reboot.

Regards,

VCP-DCV, VCP-DT, VCAP-DCD, VSP, VTSP
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arturka
Expert
Expert

rsaha wrote:

Thanks guys.Till I have confusion.What type of OS failure can it detect?

Say,my OS crashed...natuarally it won't get heartbeat from that VMs(am I right?).

hi

When your OS creashed, VMtools stops responding to HA, and also CPU, LAN and DISK activity will indicate that OS crashed

Thanks guys.Till I have confusion.What type of OS failure can it detect?

All OS versions supported by VMware as guest OS, one requirments is to have VMtools installed on guest OS

VCDX77 My blog - http://vmwaremine.com
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rsaha
Enthusiast
Enthusiast

If my OS crashed.Then what is the use of HA?.I need to rebuild the guest OS.

So how HA works?

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AndreTheGiant
Immortal
Immortal

A OS crashed does not mean that the OS must be reinstalled... Could also be an exeption (for example).

Andre

Andrew | http://about.me/amauro | http://vinfrastructure.it/ | @Andrea_Mauro
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AureusStone
Expert
Expert

Arturka, the Symantec product you are talking about is ApplicationHA.

App monitoring is actually a new feature of vSphere 5.

Here is a post from yellowbricks

http://www.yellow-bricks.com/2011/08/11/vsphere-5-0-ha-application-monitoring-intro/

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vivari
Enthusiast
Enthusiast

Hai,

     HA  is not a fault tolerant(provides uninterruptable access). It is a reactive system, which react to a problem(failed host). So it doesnot repair the faied host it does what required after a failure occures to host and lead to restarting VM's on other host which is having plenty of resources to hold VM's.

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rsaha
Enthusiast
Enthusiast

At the same time I found following feature as mentioned in VMware-High-Availability-DS-EN.pdf

Automatic detection of operating system failures ->>

__________________________________________________

Agreed,but unable to understand above stmt in VMware-High-Availability-DS-EN.pdf.

as mentioned earlier.

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a_p_
Leadership
Leadership

What is meant by "Operating System Failure" is usually a blue screen in Windows or a panic in Linux. HA monitors the VMware Tools heartbeat as well as network and disk activity of the guest. If neither are detected, HA powers off the VM (like pulling the power plug) and tries to restart the VM.

André

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