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From Sateesh Chodapuneedi <sateesh.chodapune...@citrix.com>
Subject RE: HA question
Date Thu, 28 Feb 2013 06:01:05 GMT
> -----Original Message-----
> From: Hari Kannan [mailto:hari.kannan@citrix.com]
> Sent: 28 February 2013 10:36
> To: kdamage@apache.org; cloudstack-dev@incubator.apache.org
> Subject: RE: HA question
> 
> Hi Kelcey,
> 
> At the risk of stating the obvious, I just wish to re-iterate my earlier point - with
> CloudStack, HA is for VM, not for host. That is different than VMware's HA in
> someways - in VMware, if a cluster is HA, when any host crashes, all VMs on that
> host will be restarted on a different host. With cloudstack, only VMs that are HA
> enabled will be restarted.

Yes, wanted to add more here...
VMware provides granular options at level of VM to override the cluster lelvel setting.
That means even if a host in a HA enabled cluster, crashes, only those VMs that are
marked for HA would be taken care. Apart from that it is also possible to override 
other HA parameters like priority etc. 

Regards,
Sateesh

> 
> At least, that is the way I understand this..
> 
> I also wonder what happens in CloudStack if a host crashes (assume there were
> no VMs on it) - would CloudStack detect this host is down and reduce the
> available capacity?
> 
> Hari
> 
> -----Original Message-----
> From: Kelcey Damage (BT) [mailto:kelcey@backbonetechnology.com] On Behalf
> Of kdamage@apache.org
> Sent: Wednesday, February 27, 2013 8:51 PM
> To: cloudstack-dev@incubator.apache.org
> Cc: Hari Kannan
> Subject: RE: HA question
> 
> So it's safe to conclude that HA while enabled on the host(As in the module),
> must be available cluster wide(uniform cluster). This is how VMware and others
> operate.
> 
> Thanks all.
> 
> -Kelcey
> 
> 
> >-----Original Message-----
> >From: Sateesh Chodapuneedi [mailto:sateesh.chodapuneedi@citrix.com]
> >Sent: Wednesday, February 27, 2013 8:46 PM
> >To: cloudstack-dev@incubator.apache.org
> >Cc: Hari Kannan
> >Subject: RE: HA question
> >
> >For VMware, CloudStack uses native HA provided by VMware.
> >VMware provides HA at the level of cluster.
> >
> >Regards,
> >Sateesh
> >
> >> -----Original Message-----
> >> From: Nitin Mehta [mailto:Nitin.Mehta@citrix.com]
> >> Sent: 28 February 2013 10:13
> >> To: cloudstack-dev@incubator.apache.org
> >> Cc: Hari Kannan
> >> Subject: Re: HA question
> >>
> >> CS has its own HA logic and doesn't use the native HA of the HV and
> >> so the question for enabling the HA for hosts doesn't arise. This is
> >> true
> for XS.
> >> For Vmware and KVM, I will let the guru's speak :)
> >>
> >> On 28/02/13 9:55 AM, "kdamage@apache.org" <kdamage@apache.org>
> >wrote:
> >>
> >> >Thanks that¹s awesome, but not quite the answer I was looking for.
> >> >
> >> >To better phrase my question, if the cluster is the basic unit of
> >> >availability, when hosts are enabled for HA, must all hosts in the
> >> >cluster be enabled? Or can the cluster exist with a non-uniform
> >> >structure, having only some hosts enabled for HA?
> >> >
> >> >You partially answered it with the special reserve HA hosts, but I'm
> >> >looking more in terms of general use.
> >> >
> >> >Thanks
> >> >
> >> >-kelcey
> >> >
> >> >
> >> >>-----Original Message-----
> >> >>From: Hari Kannan [mailto:hari.kannan@citrix.com]
> >> >>Sent: Wednesday, February 27, 2013 8:21 PM
> >> >>To: cloudstack-dev@incubator.apache.org
> >> >>Subject: RE: HA question
> >> >>
> >> >>Hi Kelsey,
> >> >>
> >> >>HA is at 2 levels ­ VMs can be marked HA. In addition, you can mark
> >> >>some hosts as reserved for ³Dedicated² HA hosts. Quoting from the
> >> >>manual, the dedicated HA option is set through a special host tag
> >> >>when the host is created.
> >> >>To allow the administrator to dedicate hosts to only HA-enabled
> >> >>VMs, set the global configuration variable ha.tag to the desired
> >> >>tag (for example, "ha_host"), and restart the Management Server.
> >> >>Enter the value in the Host Tags field when adding the host(s) that
> >> >>you want to dedicate to HA-enabled VMs.
> >> >>
> >> >>Hari
> >> >>
> >> >>From: Kelcey Damage (BT) [mailto:kelcey@backbonetechnology.com]
> >> >>Sent: Wednesday, February 27, 2013 8:00 PM
> >> >>To: CloudStack dev list
> >> >>Subject: RE: HA question
> >> >>
> >> >>Hi,
> >> >>
> >> >>I can¹t remember, do we enable HA on a per host basis, or on a per
> >> >>cluster basis?
> >> >>
> >> >>Thanks.
> >> >>
> >> >>[cid:image001.png@01CE1524.FA0D61B0]Kelcey Damage Infrastructure
> >> >>Systems Architect
> >>
> >>>www.backbonetechnology.com<http://www.backbonetechnology.com/>
> >> >>-------------------------------------------------------------------
> >> >>-
> >> >>-----
> >>
> >>>kelcey@backbonetechnology.com<mailto:kelcey@backbonetechnology.co
> >m
> >> >>>
> >> >>
> >> >>address: 55 East 7th Ave, Vancouver, BC, V5T 1M4
> >> >>tel: +1 604 713 8560 ext:114
> >> >>fax: +1 604 605 0964
> >> >>skype: kelcey.damage
> >> >>
> >> >
> >> >
> 


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