[Engine-devel] Proposal for support ISO domain on other types of file based storage.

[Shu Ming]

Mark Wu :
> On Sun 17 Mar 2013 10:12:55 PM CST, Ayal Baron wrote:
>>
>>
>> ----- Original Message -----
>>>
>>> Hi guys,
>>>
>>> Currently, ISO domain is only supported on NFS storage. It could
>>> improve the ease of use if it allows other types
>>> of file based storage to store ISO images. After an investigation, I
>>> found there's not any restriction on this idea.
>>> So the whole work is removing the limitation on engine side. That
>>> means engine should allow ISO domain could
>>> have different storage type from the data center it's attached, like
>>> what we do with nfs ISO domain in SAN DC.
>>>
>>> I start this idea with localfs. I know local storage can't be seen in
>>> cluster level. But it also provides a choice if no
>>> NFS available. VMs can be created on the host which has the ISO repo,
>>> and then be migrated to any other host in the cluster.
>>> I have done the initial patches: allow creation ISO domain on localfs
>>> [1] and support import ISO domain on localfs [2]
>>> I don't have much experience in java/j2ee/web development and engine
>>> architecture. The patches just work for me.
>>> I am not sure if it will bring some potential problems. So any
>>> feedback on the patch or the idea will be appreciated very much.
>>
>> Haven't looked at the patches yet, but wrt the idea, I agree on the 
>> need (being able to attach ISOs from anywhere and not just nfs) but I 
>> think the way to do this should be by getting rid of the ISO domain 
>> type altogether.
>
> I think ISO domain on localfs is useful for a simple setup or demo, 
> such as oVirt all-in-one.
>
>> Basically what we need is:
>> 1. a way to connect to file based storage (let's leave block aside 
>> for now) - this already exists via the connectStorageServer verb
>> 2. a way to list and present a file system tree in gui (give an 
>> arbitrary path to vdsm and list content) and possibly filter results 
>> by type (vfd, iso) - does not exist today. Possibly some security 
>> aspects here that need hashing out.
>> 3. a way to specify a path to a file when attaching an iso/vfd to a 
>> VM - this is the way it works today
>>
>> This would devoid the need for isoUploader and allow users to simply 
>> manage an nfs export with files.
>> Next step would be to make connectStorageServer support httpfs [1] 
>> and then we'd be able to mount ISOs directly over http (hopefully 
>> this would be sufficient to support ISOs stored on S3, swift, glance, 
>> etc).
>
> Actually, we could use the qemu curl backend image support directly. 
> That means we don't need mount the place storing ISO images. We can 
> just maintain a list of ISO image with its link, which could be http, 
> ftp and ssh.

That will be fine to start a VM on a existing extern ISO image. I also 
would like to maintain a ISO image cache on the local host to avoid to 
re-streaming the ISO image from the ISO image repositories every time. 
That will be helpful for people who is suffered from the network bottleneck.

>
>>
>> [1] http://httpfs.sourceforge.net/
>>
>>>
>>>
>>> Mark.
>>>
>>> [1] http://gerrit.ovirt.org/#/c/12687/
>>> [2] http://gerrit.ovirt.org/#/c/12916/
>>>
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>>>
>>
>
>
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-- 
---
舒明 Shu Ming
Open Virtualization Engineerning; CSTL, IBM Corp.
Tel: 86-10-82451626  Tieline: 9051626 E-mail: shuming at cn.ibm.com or shuming at linux.vnet.ibm.com
Address: 3/F Ring Building, ZhongGuanCun Software Park, Haidian District, Beijing 100193, PRC