Open Stack

On Wed, Mar 5, 2014 at 8:59 AM, Qin Zhao <chaochin at gmail.com> wrote:
> Hi Joe,
> If we assume the user is willing to create a new instance, the workflow you
> are saying is exactly correct. However, what I am assuming is that the user
> is NOT willing to create a new instance. If Nova can revert the existing
> instance, instead of creating a new one, it will become the alternative way
> utilized by those users who are not allowed to create a new instance.
> Both paths lead to the target. I think we can not assume all the people
> should walk through path one and should not walk through path two. Maybe
> creating new instance or adjusting the quota is very easy in your point of
> view. However, the real use case is often limited by business process. So I
> think we may need to consider that some users can not or are not allowed to
> creating the new instance under specific circumstances.
>

What sort of circumstances would prevent someone from deleting and
recreating an instance?

>
> On Thu, Mar 6, 2014 at 12:02 AM, Joe Gordon <joe.gordon0 at gmail.com> wrote:
>>
>> On Tue, Mar 4, 2014 at 6:21 PM, Qin Zhao <chaochin at gmail.com> wrote:
>> > Hi Joe, my meaning is that cloud users may not hope to create new
>> > instances
>> > or new images, because those actions may require additional approval and
>> > additional charging. Or, due to instance/image quota limits, they can
>> > not do
>> > that. Anyway, from user's perspective, saving and reverting the existing
>> > instance will be preferred sometimes. Creating a new instance will be
>> > another story.
>> >
>>
>> Are you saying some users may not be able to create an instance at
>> all? If so why not just control that via quotas.
>>
>> Assuming the user has the power to rights and quota to create one
>> instance and one snapshot, your proposed idea is only slightly
>> different then the current workflow.
>>
>> Currently one would:
>> 1) Create instance
>> 2) Snapshot instance
>> 3) Use instance / break instance
>> 4) delete instance
>> 5) boot new instance from snapshot
>> 6) goto step 3
>>
>> From what I gather you are saying that instead of 4/5 you want the
>> user to be able to just reboot the instance. I don't think such a
>> subtle change in behavior is worth a whole new API extension.
>>
>> >
>> > On Wed, Mar 5, 2014 at 3:20 AM, Joe Gordon <joe.gordon0 at gmail.com>
>> > wrote:
>> >>
>> >> On Tue, Mar 4, 2014 at 1:06 AM, Qin Zhao <chaochin at gmail.com> wrote:
>> >> > I think the current snapshot implementation can be a solution
>> >> > sometimes,
>> >> > but
>> >> > it is NOT exact same as user's expectation. For example, a new
>> >> > blueprint
>> >> > is
>> >> > created last week,
>> >> > https://blueprints.launchpad.net/nova/+spec/driver-specific-snapshot,
>> >> > which
>> >> > seems a little similar with this discussion. I feel the user is
>> >> > requesting
>> >> > Nova to create in-place snapshot (not a new image), in order to
>> >> > revert
>> >> > the
>> >> > instance to a certain state. This capability should be very useful
>> >> > when
>> >> > testing new software or system settings. It seems a short-term
>> >> > temporary
>> >> > snapshot associated with a running instance for Nova. Creating a new
>> >> > instance is not that convenient, and may be not feasible for the
>> >> > user,
>> >> > especially if he or she is using public cloud.
>> >> >
>> >>
>> >> Why isn't it easy to create a new instance from a snapshot?
>> >>
>> >> >
>> >> > On Tue, Mar 4, 2014 at 1:32 PM, Nandavar, Divakar Padiyar
>> >> > <divakar.padiyar-nandavar at hp.com> wrote:
>> >> >>
>> >> >> >>> Why reboot an instance? What is wrong with deleting it and
>> >> >> >>> create a
>> >> >> >>> new one?
>> >> >>
>> >> >> You generally use non-persistent disk mode when you are testing new
>> >> >> software or experimenting with settings.   If something goes wrong
>> >> >> just
>> >> >> reboot and you are back to clean state and start over again.    I
>> >> >> feel
>> >> >> it's
>> >> >> convenient to handle this with just a reboot rather than recreating
>> >> >> the
>> >> >> instance.
>> >> >>
>> >> >> Thanks,
>> >> >> Divakar
>> >> >>
>> >> >> -----Original Message-----
>> >> >> From: Joe Gordon [mailto:joe.gordon0 at gmail.com]
>> >> >> Sent: Tuesday, March 04, 2014 10:41 AM
>> >> >> To: OpenStack Development Mailing List (not for usage questions)
>> >> >> Subject: Re: [openstack-dev] [nova][cinder] non-persistent
>> >> >> storage(after
>> >> >> stopping VM, data will be rollback automatically), do you think we
>> >> >> shoud
>> >> >> introduce this feature?
>> >> >> Importance: High
>> >> >>
>> >> >> On Mon, Mar 3, 2014 at 8:13 PM, Zhangleiqiang
>> >> >> <zhangleiqiang at huawei.com>
>> >> >> wrote:
>> >> >> >>
>> >> >> >> This sounds like ephemeral storage plus snapshots.  You build a
>> >> >> >> base
>> >> >> >> image, snapshot it then boot from the snapshot.
>> >> >> >
>> >> >> >
>> >> >> > Non-persistent storage/disk is useful for sandbox-like
>> >> >> > environment,
>> >> >> > and
>> >> >> > this feature has already exists in VMWare ESX from version 4.1.
>> >> >> > The
>> >> >> > implementation of ESX is the same as what you said, boot from
>> >> >> > snapshot of
>> >> >> > the disk/volume, but it will also *automatically* delete the
>> >> >> > transient
>> >> >> > snapshot after the instance reboots or shutdowns. I think the
>> >> >> > whole
>> >> >> > procedure may be controlled by OpenStack other than user's manual
>> >> >> > operations.
>> >> >>
>> >> >> Why reboot an instance? What is wrong with deleting it and create a
>> >> >> new
>> >> >> one?
>> >> >>
>> >> >> >
>> >> >> > As far as I know, libvirt already defines the corresponding
>> >> >> > <transient>
>> >> >> > element in domain xml for non-persistent disk ( [1] ), but it
>> >> >> > cannot
>> >> >> > specify
>> >> >> > the location of the transient snapshot. Although qemu-kvm has
>> >> >> > provided
>> >> >> > support for this feature by the "-snapshot" command argument,
>> >> >> > which
>> >> >> > will
>> >> >> > create the transient snapshot under /tmp directory, the qemu
>> >> >> > driver
>> >> >> > of
>> >> >> > libvirt don't support <transient> element currently.
>> >> >> >
>> >> >> > I think the steps of creating and deleting transient snapshot may
>> >> >> > be
>> >> >> > better to done by Nova/Cinder other than waiting for the
>> >> >> > <transient>
>> >> >> > support
>> >> >> > added to libvirt, as the location of transient snapshot should
>> >> >> > specified by
>> >> >> > Nova.
>> >> >> >
>> >> >> >
>> >> >> > [1] http://libvirt.org/formatdomain.html#elementsDisks
>> >> >> > ----------
>> >> >> > zhangleiqiang
>> >> >> >
>> >> >> > Best Regards
>> >> >> >
>> >> >> >
>> >> >> >> -----Original Message-----
>> >> >> >> From: Joe Gordon [mailto:joe.gordon0 at gmail.com]
>> >> >> >> Sent: Tuesday, March 04, 2014 11:26 AM
>> >> >> >> To: OpenStack Development Mailing List (not for usage questions)
>> >> >> >> Cc: Luohao (brian)
>> >> >> >> Subject: Re: [openstack-dev] [nova][cinder] non-persistent
>> >> >> >> storage(after stopping VM, data will be rollback automatically),
>> >> >> >> do
>> >> >> >> you think we shoud introduce this feature?
>> >> >> >>
>> >> >> >> On Mon, Mar 3, 2014 at 6:00 PM, Yuzhou (C)
>> >> >> >> <vitas.yuzhou at huawei.com>
>> >> >> >> wrote:
>> >> >> >> > Hi stackers,
>> >> >> >> >
>> >> >> >> > As far as I know ,there are two types of storage used by VM in
>> >> >> >> > openstack:
>> >> >> >> Ephemeral Storage and Persistent Storage.
>> >> >> >> > Data on ephemeral storage ceases to exist when the instance it
>> >> >> >> > is
>> >> >> >> > associated
>> >> >> >> with is terminated. Rebooting the VM or restarting the host
>> >> >> >> server,
>> >> >> >> however, will not destroy ephemeral data.
>> >> >> >> > Persistent storage means that the storage resource outlives any
>> >> >> >> > other
>> >> >> >> resource and is always available, regardless of the state of a
>> >> >> >> running
>> >> >> >> instance.
>> >> >> >> >
>> >> >> >> > There is a use case that maybe need a new type of storage,
>> >> >> >> > maybe
>> >> >> >> > we
>> >> >> >> > can
>> >> >> >> call it non-persistent storage .
>> >> >> >> > The use case is that VMs are assigned to the public ephemerally
>> >> >> >> > in
>> >> >> >> > public
>> >> >> >> areas.
>> >> >> >> > After the VM is used, new data on storage of VM ceases to exist
>> >> >> >> > when the
>> >> >> >> instance it is associated with is stopped.
>> >> >> >> > It means stop the VM, Non-persistent storage used by VM will be
>> >> >> >> > rollback
>> >> >> >> automatically.
>> >> >> >> >
>> >> >> >> > Is there any other suggestions? Or any BPs about this use case?
>> >> >> >> >
>> >> >> >>
>> >> >> >> This sounds like ephemeral storage plus snapshots.  You build a
>> >> >> >> base
>> >> >> >> image, snapshot it then boot from the snapshot.
>> >> >> >>
>> >> >> >> > Thanks!
>> >> >> >> >
>> >> >> >> > Zhou Yu
>> >> >> >> >
>> >> >> >> > _______________________________________________
>> >> >> >> > OpenStack-dev mailing list
>> >> >> >> > OpenStack-dev at lists.openstack.org
>> >> >> >> >
>> >> >> >> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>> >> >> >>
>> >> >> >> _______________________________________________
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>> >> >> >
>> >> >> > _______________________________________________
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>> >> >>
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>> >> >>
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>> >> >
>> >> >
>> >> >
>> >> >
>> >> > --
>> >> > Qin Zhao
>> >> >
>> >> > _______________________________________________
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>> >> > OpenStack-dev at lists.openstack.org
>> >> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>> >> >
>> >>
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>> >
>> >
>> >
>> >
>> > --
>> > Qin Zhao
>> >
>> > _______________________________________________
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>> >
>>
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>
>
>
>
> --
> Qin Zhao
>
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