[Engine-devel] Floating Disk feature description

[Yaniv Kaul]

On 02/02/2012 12:25 PM, Daniel Erez wrote:
>
> ----- Original Message -----
>> From: "Itamar Heim"<iheim at redhat.com>
>> To: "Daniel Erez"<derez at redhat.com>
>> Cc: engine-devel at ovirt.org
>> Sent: Thursday, February 2, 2012 9:08:56 AM
>> Subject: Re: [Engine-devel] Floating Disk feature description
>>
>> On 02/01/2012 07:04 PM, Daniel Erez wrote:
>>> Hi,
>>>
>>> Floating Disk feature description Wiki page:
>>> http://www.ovirt.org/wiki/Features/DetailedFloatingDisk
>> some questions/notes:
>> 1. why do you need a floating/not floating state? isn't a disk
>> floating
>> if it was detached from all VMs?
>> or is that only a helper property to optimize lookups?
>>
> Yes, the floating state is an indication whether the disk is attached to any VM.
> It's not a persistent property on the disk, but rather a DB view calculated value.
>
>> 2. you mention fields of disks (Floating/Shared/Managed)
>>
>> 2.1 do we have a definition of "Managed" disk somewhere?
>> I assume unmanaged would be a direct LUN, but i think we need a
>> better
>> terminology here.
> Indeed, we're looking for a better teminology. Suggestions are welcomed...
>
>> 2.2 same goes for "floating" actually... do we really want to tell
>> the
>> user the disk is "floating"?
>> I guess suggestion welcome for a better name.
> "unattached" has been mentioned once as an alternative.

Google says the world prefers 'detached':  ~196M entries vs. ~5.7M 
entries for 'unattached'.
Y.

>
>> 2.3 finally, for shared, maybe more interesting is number of VMs the
>> disk is connected to, rather than just a boolean (though i assume
>> this
>> increases complexity for calculation, or redundancy of data, and not
>> a
>> big issue)
> Actually, as part of the "Shared raw disk" feature, we do want to display the number of VMs
> (and probably a list too) the disk is connected to - in the 'Disks' sub-tab (under VMs main tab).
> Hence, it might be rather simple to show that number also in the Disks main tab
> (the list of VMs will be displayed under VMs sub-tab).
>
>> 3. List of Storage Domains in which the selected Disk resides.
>> this is only relevant for template disks?
> Yes, it's only for cloned templates.
>
>> maybe consider splitting the main grid if looking at tempalte disks
>> or
>> vm disks, and show for vm disks the storage domain in main grid?
>> maybe start with vm disks only and not consider template disks so
>> much?
> Miki?
>
>> 4. "Templates (visible for disks that reside in templates) List of
>>       Templates to which the selected Disk is attached. "
>>
>> same comment as above of maybe consider only vm disks for now.
>> and also a question - how can a template disk belong to more than a
>> single template?
> Yes, for now, a template disk cannot belong to more than a single template.
> However, won't we like to have a shared disk for a template in the future?
>
>> which again hints for a template disk you would want another view,
>> with
>> the template name in the main grid
>>
>> 5. Tree: 'Resources' vs. 'free disks'
>> while i understand why separating them - naming is very confusing.
>> maybe a single node in tree and a way to filter the search from the
>> right side grid in some manner for known lookups (relevant to other
>> main
>> tabs as well?)
> For now, we've agreed that sorting abilities in columns is needed for easing the orientation.
>
>> 6. permissions not available for disks?
>> at all?
>> what do you mean power user would be able to attach them by their
>> type?
>> does it mean they can associate any shared disk in the system? I hope
>> i'm misunderstanding, as doesn't make sense to me.
>>
>> or is this caveat specific to the user portal and not the admin?
>> not allowing creating a floating disk from user portal is not a
>> problem
>> in my view for this phase.
>>
>> I assume anyone can add a disk on a storage domain they have quota
>> to.
>> who can edit a disk? remove a disk? attach disk to VM (which gives
>> them
>> ability to edit the disk)
>> (attach disk to VM obviously requires permission on both disk and VM)
> Since we won't support permissions on disks entities (at first stage),
> as a compromise for the power user portal, we've agreed to simply hide
> floating non shared disks from the user.
>
>> 7. related features
>> - data ware house may be affected by disks being unattached, or
>> shared
>> between multiple disks.
>>
>>
>>
>>
>>
>>
>>
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