Open Stack

Your case is valid and I use it also. Using 2 cores as 8 virtual cores
for _one_ machine is not the same thing.

On Mon, Dec 23, 2013 at 11:03 PM, Joshua Harlow <harlowja at yahoo-inc.com> wrote:
> It depends on the use-case, there is a point when most of the time the VMs
> on the compute node are idle.
>
> A use-case yahoo! is doing is letting developers have many VMs, in this
> case those VMs are mostly idle.
>
> Given a hypervisor with 12 cores, we can place say 12x2 core VMs on there,
> this is a total of 24 VM cores, in reality most of the time *all* the
> developers using those VMs will not be utilizing all 24 'virtual' cores
> (highly unlikely that all those users conspired to do this at the same
> time, even if they do this is where the linux scheduler will get
> involved). So there are reasons to do this (save money, improve
> efficiency), of course figuring out the right balance is up to u. Likely
> don't do 8 vms cores on a 2 core box, I would recommend buying better
> hardware before u do this ;)
>
> On 12/23/13, 12:55 PM, "Cristian Falcas" <cristi.falcas at gmail.com> wrote:
>
>>There is no point in using 8 virtual cores in compute node with 2
>>cores. The same is valid for using swap as memory to reach the desired
>>12gb.
>>
>>Of course, if you don't plan on using that machine for any real work,
>>you can do it.
>>
>>
>>
>>On Mon, Dec 23, 2013 at 6:39 PM, Joshua Harlow <harlowja at yahoo-inc.com>
>>wrote:
>>> Nope, u can over provision on most all of the resources (CPU, ram,
>>>disk) u
>>> described there. Ram is the tricky one as the Linux oom killer may
>>>start to
>>> get involved when u push the ram limits to high. But there is nothing
>>> stopping u from running 8 or more vms on a box, depending on the over
>>> provision ratio u are ok with...
>>>
>>> Sent from my really tiny device...
>>>
>>> On Dec 23, 2013, at 3:55 AM, "Vikas Parashar" <para.vikas at gmail.com>
>>>wrote:
>>>
>>> Thanks Cristian,
>>>
>>> Will elasticity  be limited to 4 Cores/4GB  (The max capacity of a
>>>physical
>>> host) ?
>>>
>>>
>>> On Mon, Dec 23, 2013 at 5:00 PM, Cristian Falcas
>>><cristi.falcas at gmail.com>
>>> wrote:
>>>>
>>>> Hi,
>>>>
>>>> From what I know you can resize a machine, but this involves
>>>> rebuilding the instance: openstack will create a snapshot of the
>>>> machine an recreate the instance with the new snapshot and a new
>>>> flavor. This is not very fast from my experience, so you will have a
>>>> considerable downtime doing this, depending on the size of the current
>>>> instance and how fast is your storage.
>>>>
>>>> Best regards,
>>>> Cristian Falcas
>>>>
>>>>
>>>>
>>>> On Mon, Dec 23, 2013 at 12:03 PM, Vikas Parashar <para.vikas at gmail.com>
>>>> wrote:
>>>> > Hi,
>>>> >
>>>> > IaaS is all about elastic computing. I can stretch resources as per
>>>>my
>>>> > need
>>>> > - increasing/decreasing the number of cores, RAM allocated etc..
>>>> >
>>>> > My question is - how does openStack achieve this elasticity for both
>>>> > computation and RAM.
>>>> >
>>>> > If I create an image with 2 cores and 4 GB RAM (and one day I need to
>>>> > increase this to, lets say - 6 Cores and 12 GB RAM), but all the
>>>> > physical
>>>> > hosts that I currently have (for Compute and RAM) at my disposal
>>>>have a
>>>> > max
>>>> > of 4 Cores and 4 GB RAM each..
>>>> >
>>>> > Using openStack -
>>>> >
>>>> > a) is this possible (as long as the total cores and total RAM
>>>>required
>>>> > is
>>>> > less than the group-total) ? If yes, how is this achieved.
>>>> >
>>>> > b) or the elasticity will be limited to 4 Cores/4GB  (The max
>>>>capacity
>>>> > of a
>>>> > physical host) ? If no, then is it possible to achieve it ?
>>>> >
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>>>
>>>
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>