Open Stack

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.


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
> >> >>
> >> >> _______________________________________________
> >> >> OpenStack-dev mailing list
> >> >> OpenStack-dev at lists.openstack.org
> >> >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> >> >
> >> > _______________________________________________
> >> > OpenStack-dev mailing list
> >> > OpenStack-dev at lists.openstack.org
> >> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> >>
> >> _______________________________________________
> >> OpenStack-dev mailing list
> >> OpenStack-dev at lists.openstack.org
> >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> >>
> >> _______________________________________________
> >> OpenStack-dev mailing list
> >> OpenStack-dev at lists.openstack.org
> >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> >
> >
> >
> >
> > --
> > Qin Zhao
> >
> > _______________________________________________
> > OpenStack-dev mailing list
> > OpenStack-dev at lists.openstack.org
> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> >
>
> _______________________________________________
> OpenStack-dev mailing list
> OpenStack-dev at lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>



-- 
Qin Zhao
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstack.org/pipermail/openstack-dev/attachments/20140305/27b6a647/attachment.html>