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On 25/08/20 12:05 am, Dmitry Tantsur wrote:
>
>
> On Mon, Aug 24, 2020 at 1:52 PM Sean Mooney <smooney at redhat.com 
> <mailto:smooney at redhat.com>> wrote:
>
>     On Mon, 2020-08-24 at 10:32 +0200, Dmitry Tantsur wrote:
>     > Hi,
>     >
>     > On Mon, Aug 24, 2020 at 10:24 AM Arne Wiebalck
>     <arne.wiebalck at cern.ch <mailto:arne.wiebalck at cern.ch>>
>     > wrote:
>     >
>     > > Hi!
>     > >
>     > > CERN's deployment is using the iscsi deploy interface since we
>     started
>     > > with Ironic a couple of years ago (and we installed around
>     5000 nodes
>     > > with it by now). The reason we chose it at the time was
>     simplicity: we
>     > > did not (and still do not) have a Swift backend to Glance, and
>     the iscsi
>     > > interface provided a straightforward alternative.
>     > >
>     > > While we have not seen obscure bugs/issues with it, I can
>     certainly back
>     > > the scalability issues mentioned by Dmitry: the tunneling of
>     the images
>     > > through the controllers can create issues when deploying
>     hundreds of
>     > > nodes at the same time. The security of the iscsi interface is
>     less of a
>     > > concern in our specific environment.
>     > >
>     > > So, why did we not move to direct (yet)? In addition to the
>     lack of
>     > > Swift, mostly since iscsi works for us and the scalability
>     issues were
>     > > not that much of a burning problem ... so we focused on other
>     things :)
>     > >
>     > > Here are some thoughts/suggestions for this discussion:
>     > >
>     > > How would 'direct' work with other Glance backends (like
>     Ceph/RBD in our
>     > > case)? If using direct requires to duplicate images from Glance to
>     > > Ironic (or somewhere else) to be served, I think this would be an
>     > > argument against deprecating iscsi.
>     > >
>     >
>     > With image_download_source=http ironic will download the image
>     to the
>     > conductor to be able serve it to the node. Which is exactly what
>     the iscsi
>     > is doing, so not much of a change for you (except for
>     s/iSCSI/HTTP/ as a
>     > means of serving the image).
>     >
>     > Would it be an option for you to test direct deploy with
>     > image_download_source=http?
>     i think if there is still an option to not force deployemnt to
>     altere any of there
>     other sevices this is likely ok but i think the onious shoudl be
>     on the ironic
>     and ooo teams to ensure there is an upgrade path for those useres
>     before this deprecation
>     becomes a removal without deploying swift or a swift compatibale
>     api e.g. RadosGW
>
>
> Swift is NOT a requirement (nor is RadosGW) when 
> image_download_source=http is used. Any glance backend (or no glance 
> at all) will work.

Even though the TripleO undercloud has swift, I'd be inclined to do 
image_download_source=http so that it can scale out to minions, and so 
we're not relying on a single-node swift for image serving

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