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From "Kelceydamage@bbits" <kel...@bbits.ca>
Subject Re: HA question
Date Thu, 28 Feb 2013 08:18:05 GMT
Cool, more fuel to get a proper section on HA.

Sent from my iPhone

On Feb 27, 2013, at 11:51 PM, Nitin Mehta <Nitin.Mehta@citrix.com> wrote:

> I was searching for this document which used to be on docs.cloudstack.org
> but couldn't find it. Thanks for pointing this one.
> 
> On 28/02/13 1:12 PM, "Mice Xia" <mice_xia@tcloudcomputing.com> wrote:
> 
>> There is a document describing HA in details, you can check it on:
>> http://people.apache.org/~mice/CloudStackHighAvailability.pdf
>> 
>> this document is a little outdated, but the concepts and overall workflow
>> still apply.
>> 
>> Regards
>> Mice
>> 
>> -----Original Message-----
>> From: Kelceydamage@bbits [mailto:kelcey@bbits.ca]
>> Sent: Thursday, February 28, 2013 3:24 PM
>> To: cloudstack-dev@incubator.apache.org
>> Cc: cloudstack-dev@incubator.apache.org
>> Subject: Re: HA question
>> 
>> I could get one started.
>> 
>> I've saved this thread, and I'll try to get some stuff up in the next
>> couple days.
>> 
>> Sent from my iPhone
>> 
>> On Feb 27, 2013, at 10:57 PM, Nitin Mehta <Nitin.Mehta@citrix.com> wrote:
>> 
>>> Kelcey - Would you be willing to put a HA wiki ? I promise to
>>> volunteer :) with whatever I know
>>> 
>>> On 28/02/13 12:16 PM, "Kelceydamage@bbits" <kelcey@bbits.ca> wrote:
>>> 
>>>> This is turning out to be a great discussion to have. Now I get that
>>>> CloudStack HA is purely handled by the  management/orchestration
>>>> engine and only if VM is tagged(which I knew). But what is good to
>>>> find out is that it does not involve underlying hypervisor specific
>>>> HA modules(except perhaps VMware). Incidentally VMwares HA mechanism
>>>> is also called storage
>>>> heartbeat(5.x+) but it uses hypervisor modules as well.
>>>> 
>>>> I do agree with Ahmad that it might be worth looking into expanding
>>>> our HA suite to support hypervisor specific HA modules as an override
>>>> to the default CS HA.
>>>> 
>>>> There has not been too many HA discussions on the mailing list, and
>>>> by the looks of it we were all under slightly different impressions.
>>>> 
>>>> Thanks again for the good discussion.
>>>> 
>>>> Sent from my iPhone
>>>> 
>>>> On Feb 27, 2013, at 9:48 PM, Ahmad Emneina <aemneina@gmail.com> wrote:
>>>> 
>>>>> I would imagine it's best to leverage on the underlying hypervisors'
>>>>> HA mechanisms, configured oud-of-band of cloudstack. I find
>>>>> cloudstacks implementation a little laggy compared to the paid for
>>>>> variety.
>>>>> CloudStack
>>>>> does a well enough job to figure out which host the vm eventually
>>>>> lands on.
>>>>> 
>>>>> 
>>>>> On Wed, Feb 27, 2013 at 9:37 PM, Mice Xia
>>>>> <mice_xia@tcloudcomputing.com>wrote:
>>>>> 
>>>>>> Currently for xenserver/KVM, Cloudstack uses 'storage heartbeat'
to
>>>>>> detect whether it should start HA, i.e. agent resides on
>>>>>> xenserver/KVM periodically writes a timestamp on shared storage,
if
>>>>>> host network pingTimeOut happens, Cloudstack will investigate if
>>>>>> 'storage heartbeat'
>>>>>> timeout and if that's the case HA job will be launched for HA
>>>>>> enabled VMs on the host.
>>>>>> 
>>>>>> It's a simplified procedure, HA implementation involves delta sync/
>>>>>> investigators and fencers.
>>>>>> 
>>>>>> -Mice
>>>>>> 
>>>>>> -----Original Message-----
>>>>>> From: Sanjeev Neelarapu [mailto:sanjeev.neelarapu@citrix.com]
>>>>>> Sent: Thursday, February 28, 2013 1:21 PM
>>>>>> To: cloudstack-dev@incubator.apache.org; kdamage@apache.org
>>>>>> Subject: RE: HA question
>>>>>> 
>>>>>> Hi Hari,
>>>>>> 
>>>>>> AFAIK, in CloudStack if a host crashes CloudStack would detect the
>>>>>> host as down after pingTimeout interval.
>>>>>> CloudStack does not reduce the available capacity because the host
>>>>>> capacity values are not removed from op_host_capacity table. It
>>>>>> assumes the host down is a temporary issue.
>>>>>> 
>>>>>> Thanks,
>>>>>> Sanjeev
>>>>>> 
>>>>>> -----Original Message-----
>>>>>> From: Hari Kannan [mailto:hari.kannan@citrix.com]
>>>>>> Sent: Thursday, February 28, 2013 10:36 AM
>>>>>> 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.
>>>>>> 
>>>>>> 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.c
>>>>>>>>> o
>>>>>>> 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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