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Re: Snapshots only on Primary Storage feature


Si / Will,

That is just FYI, if anyone uses VMware with that flag set to false. I'm
neither against the feature nor telling to rip that out.

You are correct, the PR 2081 supports KVM and Xen as the volume snapshots
are directly supported on them and backup operation is not tightly coupled
with the create operation.

-Suresh

On Fri, May 18, 2018 at 7:38 PM, Simon Weller <sweller@xxxxxxx.invalid>
wrote:

> There are plenty of features in ACS that are particular to a certain
> hypervisor (or hypervisor set), including VMware specific items.
>
> It was never claimed this feature worked across all hypervisors. In
> addition to that, the default was to leave the existing functionality
> exactly the way it was originally implemented and if a user wished to
> change the functionality they could via a global config variable.
>
> Your original spec for PR 2081 in confluence states that the PR was
> targeted towards KVM and Xen, so I'm confused as to why VMware is even
> being mentioned here.
>
>
> This is a major feature regression that a number of organizations/service
> providers are relying on and it wasn't called out when the PR was submitted.
>
>
> ________________________________
> From: Will Stevens <wstevens@xxxxxxxxxxxx>
> Sent: Friday, May 18, 2018 6:12 AM
> To: dev@xxxxxxxxxxxxxxxxxxxxx
> Subject: Re: Snapshots only on Primary Storage feature
>
> Just because it does not work for VMware should not a reason to rip out the
> functionality for other hypervisors where it is being used though.
>
> I know we also have the requirement that snapshots are not automatically
> replicated to secondary storage, so this feature is useful to us.
>
> I don't understand the rational for removing the feature just because it
> does not work on VMware.
>
> On Fri, May 18, 2018, 6:27 AM Suresh Kumar Anaparti, <
> sureshkumar.anaparti@xxxxxxxxx> wrote:
>
> > Si,
> >
> > The PR# 1697 with the global setting *snapshot.backup.rightafter** -
> > false* doesn't
> > work for VMware as create snapshot never takes a snapshot in Primary
> pool,
> > it just returns the snapshot uuid. The backup snapshot does the complete
> > job - creates a VM snapshot with the uuid, extracts and exports the
> target
> > volume to secondary. On demand backup snapshot doesn't work as there is
> no
> > snapshot in primary. Also, there'll be only one entry with Primary store
> > role in snapshot_store_ref, which is the latest snapshot taken for that
> > volume.
> >
> > -Suresh
> >
> > On Fri, May 18, 2018 at 1:03 AM, Simon Weller <sweller@xxxxxxx.invalid>
> > wrote:
> >
> > > The whole point of the original PR was to optionally disable this
> > > functionality.
> > >
> > > We don't expose views of the backup state to our customers (we have our
> > > own customer interfaces) and it's a large waste of space for us to be
> > > backing up tons of VM images when we have a solid primary storage
> > > infrastructure that already has lots of resiliency.
> > >
> > >
> > > I guess we're going to have to revisit this again before we can
> consider
> > > rebasing on 4.11.
> > >
> > > ________________________________
> > > From: Suresh Kumar Anaparti <sureshkumar.anaparti@xxxxxxxxx>
> > > Sent: Thursday, May 17, 2018 2:21 PM
> > > To: dev
> > > Subject: Re: Snapshots only on Primary Storage feature
> > >
> > > Hi Si,
> > >
> > > No. not possible to disable the backup to secondary. It copies the
> volume
> > > snapshot to secondary in a background thread using asyncBackup param
> (set
> > > to true) and allows other operations during that time.
> > >
> > > I understand that the backup was on demand when any operations are
> > > performed on the snapshot. But, backup during that time may take
> > > considerable time (depending on the snapshot size and the network
> > > bandwidth), which can result in the job timeout and the User may assume
> > > that it is already Backed up based on its state, unless it is
> documented.
> > >
> > > -Suresh
> > >
> > > On Fri, May 18, 2018 at 12:23 AM, Simon Weller <sweller@xxxxxxx.invalid
> >
> > > wrote:
> > >
> > > > Suresh,
> > > >
> > > >
> > > > With this new merged  PR, is it possible to disable the backup to
> > > > secondary completely? I can't tell from the reference spec and we're
> > not
> > > on
> > > > a 4.10/4.11 base yet.
> > > >
> > > > For the record, in the instances where a volume or template from
> > snapshot
> > > > was required, the backup image was copied on demand to secondary.
> > > >
> > > > In an ideal world, secondary storage wouldn't even be involved in
> most
> > of
> > > > these options, instead using the native clone features of the
> > underlying
> > > > storage.
> > > >
> > > >
> > > > - Si
> > > >
> > > > ________________________________
> > > > From: Suresh Kumar Anaparti <sureshkumar.anaparti@xxxxxxxxx>
> > > > Sent: Thursday, May 17, 2018 1:37 PM
> > > > To: dev@xxxxxxxxxxxxxxxxxxxxx
> > > > Cc: Nathan Johnson
> > > > Subject: Re: Snapshots only on Primary Storage feature
> > > >
> > > > Hi Glen / Si,
> > > >
> > > > In PR# 1697, the global setting *snapshot.backup.rightafter* if set
> to
> > > > true, it'll be the default behaviour and snapshot is copied to the
> > > > secondary storage. If set to false, then the snapshot state
> transitions
> > > are
> > > > mocked and Snapshot would be in BackedUp state even though it is not
> > > really
> > > > in Secondary storage, which doesn't make sense. Also, that will
> enable
> > to
> > > > create a volume or template from the snapshot, which will obviously
> > fail.
> > > >
> > > > This behavior was changed with the PR
> > > > https://github.com/apache/cloudstack/pull/2081. There is a clear
> > > > separation
> > > > of create and backup volume snapshot operations. The global setting
> > > > *snapshot.backup.rightafter* has been removed in PR# 2081.
> > > >
> > > > -Suresh
> > > >
> > > > On Thu, May 17, 2018 at 8:40 PM, Simon Weller
> <sweller@xxxxxxx.invalid
> > >
> > > > wrote:
> > > >
> > > > > Glen,
> > > > >
> > > > >
> > > > > This feature was implemented in 4.9 by my colleague Nathan Johnson.
> > > You
> > > > > enable it by changing the global setting
> snapshot.backup.rightafter
> > to
> > > > > false.
> > > > >
> > > > >
> > > > > The PR is reference here: https://github.com/apache/
> > > cloudstack/pull/1697
> > > > >
> > > > >
> > > > > We have the exact same use case as you, as we also use Ceph.
> > > > >
> > > > >
> > > > > - Si
> > > > >
> > > > >
> > > > > ________________________________
> > > > > From: Glen Baars <glen@xxxxxxxxxxxxxxxxxxxxxx>
> > > > > Sent: Thursday, May 17, 2018 9:46 AM
> > > > > To: dev@xxxxxxxxxxxxxxxxxxxxx
> > > > > Subject: Snapshots only on Primary Storage feature
> > > > >
> > > > >
> > > > > Hello Devs,
> > > > >
> > > > >
> > > > >
> > > > > I have been thinking about a feature request and want to see what
> > > people
> > > > > think about the use case.
> > > > >
> > > > >
> > > > >
> > > > > We use KVM + Ceph RBD as storage.
> > > > >
> > > > >
> > > > >
> > > > > Currently, when a client takes a snapshot, Cloudstack takes a Ceph
> > > > > snapshot and then uses qemu-img to export to secondary storage.
> This
> > > > > creates a full backup of the server. Clients want to use this as a
> > > daily
> > > > > snapshot and it isn’t feasible due to the space requirements.
> > > > >
> > > > >
> > > > >
> > > > > We would like create the snapshot only on primary storage. It is
> > > > > replicated offsite and fault tolerant. I can see that the download
> > > > snapshot
> > > > > and create template features may be an issue.
> > > > >
> > > > >
> > > > >
> > > > > I have seen the below features in the recent releases and wondered
> if
> > > > this
> > > > > was the direction that the development was going.
> > > > >
> > > > > Separation of volume snapshot creation on primary storage and
> backing
> > > > > operation on secondary storage.
> > > > >
> > > > > Bypass secondary storage template copy/transfer for KVM.
> > > > >
> > > > > Kind regards,
> > > > >
> > > > > Glen Baars
> > > > >
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