[Openstack] multi-nic blueprint - data migration

Ramesh Durairaj dramesh at gmail.com
Tue Mar 29 14:30:22 UTC 2011


Also, curious, who assigns mac_addresses? or how the table is built initially?

Ram

On Tue, Mar 29, 2011 at 2:45 AM, Ishimoto, Ryu <ryu at midokura.jp> wrote:
>
> ahhh yes, I misread the blueprint, it makes a lot of sense now.  Thanks.
> Does this mean that when an instance launches, all the MAC
> addresses/Networks that belong in the same project get assigned to that
> instance?   I couldn't find this in the code so I just wanted to verify.
> Ryu
> On Tue, Mar 29, 2011 at 1:13 AM, Trey Morris <trey.morris at rackspace.com>
> wrote:
>>
>> Ryu, the new mac_address table is going to associate a mac_address with an
>> instance and a network. When the VIFs are created for the instance, they are
>> given the mac_address from the table and attached to the network from the
>> table. Does that help?
>> -trey
>>
>> On Mon, Mar 28, 2011 at 10:54 AM, Ishimoto, Ryu <ryu at midokura.jp> wrote:
>>>
>>> Thanks, that cleared it up for me.
>>> Staying on the topic of multi-nics, I have been trying to understand the
>>> direction in which Nova is going in regards to networking, and reading up on
>>> the multi-nics blueprint, it certainly seems like it's going in the right
>>> direction, but I do have one question:
>>> What was the reasoning behind associating networks, and not NICs, to an
>>> instance?  I understand that each instance NIC would belong to a distinct
>>> network, but it just seems more intuitive to imagine that an instance has
>>> NICs, and these NICs are connected to networks(or even more intuitively,
>>> connected to virtual ports that belong to various networks - Assigning a
>>> port to a NIC is like allocating an IP address).
>>> One problem I see from my suggestion above is that there is no
>>> association between NICs and networks, which means there is no way to select
>>> a network to grab an IP address from for each NIC at the time of VM launch.
>>>  I might be missing something completely here, but why not just let the user
>>> manage all this through the management  API before the VM launch?  Let the
>>> user create NICs, Networks(and Ports with IP addresses), and map the NICs to
>>> ports.  Then pass this list of 'connected' NICs as a parameter to launch a
>>> VM.  This parameter is optional, and if omitted, it should be treated as
>>> launching a single NIC instance, with a new NIC created and associated with
>>> the instance on the fly.  This prevents it from breaking the way it works
>>> now.
>>> If the concept of NICs for instance makes sense to everyone, I would love
>>> to help out and look further into what work needs to be done to extend the
>>> current multi-nic model into this one.
>>> I hope this made sense.  I apologize for the length.
>>> Thanks,
>>> Ryu
>>>
>>> On Tue, Mar 29, 2011 at 12:47 AM, Trey Morris <trey.morris at rackspace.com>
>>> wrote:
>>>>
>>>> I've written a migration to handle moving the data in the current
>>>> instances table mac_address column into the new mac_address table before the
>>>> column is removed.
>>>> I agree with Jay, data should never be discarded when migrating forward.
>>>> I don't think there has been a case yet where data is migrated in nova. This
>>>> could be the first.
>>>>
>>>> -trey
>>>>
>>>> On Mon, Mar 28, 2011 at 8:17 AM, Jay Pipes <jaypipes at gmail.com> wrote:
>>>>>
>>>>> On Mon, Mar 28, 2011 at 2:31 AM, Ishimoto, Ryu <ryu at midokura.jp> wrote:
>>>>> > Hi All,
>>>>> > I was looking at the multi-nic
>>>>> >
>>>>> > blueprint(https://blueprints.launchpad.net/nova/+spec/nova-multi-nic), and
>>>>> > in particular:
>>>>> > 1) removing mac_address column from the instances table and creating
>>>>> > a
>>>>> > mac_addresses table. This is for storing which instances own which
>>>>> > mac
>>>>> > addresses as well as which network each mac is for.
>>>>> > What happens(or should happen) to the MAC addresses that are already
>>>>> > associated with instances?  Will they be migrated to the new
>>>>> > mac_addresses
>>>>> > table?  Or will they be discarded completely?
>>>>>
>>>>> Data should never be discarded in situations like this where a column
>>>>> is moved to another table's schema (or to be records in another
>>>>> table).
>>>>>
>>>>> > I was curious to know how Nova usually handles data migration issues
>>>>> > like
>>>>> > this.
>>>>>
>>>>> No idea whether/if Nova's data migrations have previously needed to
>>>>> preserve data in this way. Glance does, however, and you can use the
>>>>> following Python changescript to get an idea how to perform this exact
>>>>> type of change:
>>>>>
>>>>>
>>>>> http://bazaar.launchpad.net/~glance-core/glance/cactus-trunk/view/head:/glance/registry/db/migrate_repo/versions/003_add_disk_format.py
>>>>>
>>>>> Note that SQLite has issues if you try to add and drop columns in the
>>>>> same changescript and you also have an unrelated column that is
>>>>> indexed (see:
>>>>> http://code.google.com/p/sqlalchemy-migrate/issues/detail?id=117).
>>>>> If this is the case, you will need to write SQL-based changescripts
>>>>> specfically for SQLite. You can see examples of how this is
>>>>> accomplished in Glance for the same DB version here:
>>>>>
>>>>>
>>>>> http://bazaar.launchpad.net/~glance-core/glance/cactus-trunk/view/head:/glance/registry/db/migrate_repo/versions/003_sqlite_upgrade.sql
>>>>>
>>>>> http://bazaar.launchpad.net/~glance-core/glance/cactus-trunk/view/head:/glance/registry/db/migrate_repo/versions/003_sqlite_downgrade.sql
>>>>>
>>>>> Cheers,
>>>>> jay
>>>>>
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