[Engine-devel] VM Payload feature

[Joseph VLcek]

On Jan 22, 2012, at 3:09 AM, Oved Ourfalli wrote:

> 
> 
> ----- Original Message -----
>> From: "Ayal Baron" <abaron at redhat.com>
>> To: "Oved Ourfalli" <ovedo at redhat.com>
>> Cc: engine-devel at ovirt.org
>> Sent: Thursday, January 19, 2012 4:05:08 PM
>> Subject: Re: [Engine-devel] VM Payload feature
>> 
>> 
>> 
>> ----- Original Message -----
>>> Hey all,
>>> 
>>> Continuing the discussion about Aeolus instance data injection to a
>>> VM
>>> (http://lists.ovirt.org/pipermail/engine-devel/2012-January/000423.html)
>>> we propose a new VM Payload feature.
>>> 
>>> The following wiki page contains a description page of the feature.
>>> http://www.ovirt.org/wiki/Features/VMPayload
>>> 
>>> Please read and review.
>>> There are several approaches there, and we wish to head your
>>> opinions
>>> and thoughts about them.
>>> 
>>> Once we agree on an approach, we will start designing.
>> 
>> Permanent payload availability requires determining where the payload
>> is stored.
>> Makes sense to me to store it together with the VM disks on the
>> storage domain, but that requires the small object store which will
>> not be available in the coming version (payloads can be large and
>> keeping them in the DB and passing over the net every time the VM is
>> run doesn't make much sense).
>> 
> I guess we can start with storing it in the database, with some size limitation, and move it to the storage domain later on.
> 
>> Wrt availability, I don't see a reason to exclude attaching both a CD
>> and a payload via another CD at the same time (i.e. multiple
>> devices).
>> 
>>> 
>>> Thank you,
>>> Oved
>>> _______________________________________________
>>> Engine-devel mailing list
>>> Engine-devel at ovirt.org
>>> http://lists.ovirt.org/mailman/listinfo/engine-devel
>>> 
>> _______________________________________________
>> Engine-devel mailing list
>> Engine-devel at ovirt.org
>> http://lists.ovirt.org/mailman/listinfo/engine-devel
>> 



My perspective is that of the end user, the instance retrieving the data.

From a functional standpoint I would like to see similar performance to
what EC2 provides. AWS EC2 user data is limited to 16K. This limit
applies to the data in raw form, not base64 encoded form.
see: 
http://docs.amazonwebservices.com/AWSEC2/latest/UserGuide/instancedata-data-categories.html

I am concerned about the 512k limit as mentioned in the notes
of: http://www.ovirt.org/wiki/Features/VMPayload
"if the content of the file is bigger the 512K it will pass an nfs
share for vdsm to fetch the file/s"

Please confirm:
- Will it be possible to pass user data to larger than 512k?
- If so what will the instance need to do in order to retrieve
   user-data bigger than 512k.
- What will the MAX size supported for the user-data?

Thank you.
    Joe VLcek

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