[Gluster-devel] [Heketi] Block store related API design discussion
Niels de Vos
ndevos at redhat.com
Mon Sep 19 15:52:37 UTC 2016
On Mon, Sep 19, 2016 at 10:31:11AM -0400, Luis Pabón wrote:
> Using qemu is interesting, but the I/O should be using the IO path of QEMU block API. If not,
> TCMU would not know how to work with QEMU dynamic QCOW2 files.
>
> Now, if TCMU already has this, then that would be great!
It has a qcow2 header, maybe you guys are lucky!
https://github.com/open-iscsi/tcmu-runner/blob/master/qcow2.h
Niels
>
> - Luis
>
> ----- Original Message -----
> From: "Prasanna Kalever" <pkalever at redhat.com>
> To: "Niels de Vos" <ndevos at redhat.com>
> Cc: "Luis Pabón" <lpabon at redhat.com>, "Stephen Watt" <swatt at redhat.com>, "gluster-devel" <gluster-devel at gluster.org>, "Ramakrishna Yekulla" <rreddy at redhat.com>, "Humble Chirammal" <hchiramm at redhat.com>
> Sent: Monday, September 19, 2016 7:13:36 AM
> Subject: Re: [Gluster-devel] [Heketi] Block store related API design discussion
>
> On Mon, Sep 19, 2016 at 4:09 PM, Niels de Vos <ndevos at redhat.com> wrote:
> >
> > On Mon, Sep 19, 2016 at 03:34:29PM +0530, Prasanna Kalever wrote:
> > > On Mon, Sep 19, 2016 at 10:13 AM, Niels de Vos <ndevos at redhat.com> wrote:
> > > > On Tue, Sep 13, 2016 at 12:06:00PM -0400, Luis Pabón wrote:
> > > >> Very good points. Thanks Prasanna for putting this together. I agree with
> > > >> your comments in that Heketi is the high level abstraction API and it should have
> > > >> an API similar of what is described by Prasanna.
> > > >>
> > > >> I definitely do not think any File Api should be available in Heketi,
> > > >> because that is an implementation of the Block API. The Heketi API should
> > > >> be similar to something like OpenStack Cinder.
> > > >>
> > > >> I think that the actual management of the Volumes used for Block storage
> > > >> and the files in them should be all managed by Heketi. How they are
> > > >> actually created is still to be determined, but we could have Heketi
> > > >> create them, or have helper programs do that.
> > > >
> > > > Maybe a tool like qemu-img? If whatever iscsi service understand the
> > > > format (at the very least 'raw'), you could get functionality like
> > > > snapshots pretty simple.
> > >
> > > Niels,
> > >
> > > This is brilliant and subset of the Idea falls in one among my
> > > thoughts, only concern is about building dependencies of qemu with
> > > Heketi.
> > > But at an advantage of easy and cool snapshots solution.
> >
> > And well tested as I understand that oVirt is moving to use qemu-img as
> > well. Other tools are able to use the qcow2 format, maybe the iscsi
> > servce that gets used does so too.
> >
> > Has there already been a decision on what Heketi will configure as iscsi
> > service? I am aware of the tgt [1] and LIO/TCMU [2] projects.
>
> Niels,
>
> yes we will be using TCMU (Kernel Module) and TCMU-runner (user space
> service) to expose file in Gluster volume as an iSCSI target.
> more at [1], [2] & [3]
>
> [1] https://pkalever.wordpress.com/2016/06/23/gluster-solution-for-non-shared-persistent-storage-in-docker-container/
> [2] https://pkalever.wordpress.com/2016/06/29/non-shared-persistent-gluster-storage-with-kubernetes/
> [3] https://pkalever.wordpress.com/2016/08/16/read-write-once-persistent-storage-for-openshift-origin-using-gluster/
>
> --
> Prasanna
>
> >
> > Niels
> >
> > 1. http://stgt.sourceforge.net/
> > 2. https://github.com/open-iscsi/tcmu-runner
> > http://blog.gluster.org/2016/04/using-lio-with-gluster/
> >
> > >
> > > --
> > > Prasanna
> > >
> > > >
> > > > Niels
> > > >
> > > >
> > > >> We also need to document the exact workflow to enable a file in
> > > >> a Gluster volume to be exposed as a block device. This will help
> > > >> determine where the creation of the file could take place.
> > > >>
> > > >> We can capture our decisions from these discussions in the
> > > >> following page:
> > > >>
> > > >> https://github.com/heketi/heketi/wiki/Proposed-Changes
> > > >>
> > > >> - Luis
> > > >>
> > > >>
> > > >> ----- Original Message -----
> > > >> From: "Humble Chirammal" <hchiramm at redhat.com>
> > > >> To: "Raghavendra Talur" <rtalur at redhat.com>
> > > >> Cc: "Prasanna Kalever" <pkalever at redhat.com>, "gluster-devel" <gluster-devel at gluster.org>, "Stephen Watt" <swatt at redhat.com>, "Luis Pabon" <lpabon at redhat.com>, "Michael Adam" <madam at redhat.com>, "Ramakrishna Yekulla" <rreddy at redhat.com>, "Mohamed Ashiq Liyazudeen" <mliyazud at redhat.com>
> > > >> Sent: Tuesday, September 13, 2016 2:23:39 AM
> > > >> Subject: Re: [Gluster-devel] [Heketi] Block store related API design discussion
> > > >>
> > > >>
> > > >>
> > > >>
> > > >>
> > > >> ----- Original Message -----
> > > >> | From: "Raghavendra Talur" <rtalur at redhat.com>
> > > >> | To: "Prasanna Kalever" <pkalever at redhat.com>
> > > >> | Cc: "gluster-devel" <gluster-devel at gluster.org>, "Stephen Watt" <swatt at redhat.com>, "Luis Pabon" <lpabon at redhat.com>,
> > > >> | "Michael Adam" <madam at redhat.com>, "Humble Chirammal" <hchiramm at redhat.com>, "Ramakrishna Yekulla"
> > > >> | <rreddy at redhat.com>, "Mohamed Ashiq Liyazudeen" <mliyazud at redhat.com>
> > > >> | Sent: Tuesday, September 13, 2016 11:08:44 AM
> > > >> | Subject: Re: [Gluster-devel] [Heketi] Block store related API design discussion
> > > >> |
> > > >> | On Mon, Sep 12, 2016 at 11:30 PM, Prasanna Kalever <pkalever at redhat.com>
> > > >> | wrote:
> > > >> |
> > > >> | > Hi all,
> > > >> | >
> > > >> | > This mail is open for discussion on gluster block store integration with
> > > >> | > heketi and its REST API interface design constraints.
> > > >> | >
> > > >> | >
> > > >> | > ___ Volume Request ...
> > > >> | > |
> > > >> | > |
> > > >> | > PVC claim -> Heketi --->|
> > > >> | > |
> > > >> | > |
> > > >> | > |
> > > >> | > |
> > > >> | > | __ BlockCreate
> > > >> | > | |
> > > >> | > | |__ BlockInfo
> > > >> | > | |
> > > >> | > |___ Block Request (APIS)-> |__ BlockResize
> > > >> | > |
> > > >> | > |__ BlockList
> > > >> | > |
> > > >> | > |__ BlockDelete
> > > >> | >
> > > >> | > Heketi will have block API and volume API, when user submit a Persistent
> > > >> | > volume claim, Kubernetes provisioner based on the storage class(from PVC)
> > > >> | > talks to heketi for storage, heketi intern calls block or volume API's
> > > >> | > based on request.
> > > >> | >
> > > >> |
> > > >> | This is probably wrong. It won't be Heketi calling block or volume APIs. It
> > > >> | would be Kubernetes calling block or volume API *of* Heketi.
> > > >> |
> > > >> |
> > > >> | > With my limited understanding, heketi currently creates clusters from
> > > >> | > provided nodes, creates volumes and handover them to the user.
> > > >> | > For block related API's, it has to deal with files right ?
> > > >> | >
> > > >> | > Here is how block API's look like in short-
> > > >> | > Create: heketi has to create file in the volume and export it as a iscsi
> > > >> | > target device and hand it over to user.
> > > >> | > Info: show block stores information across all the clusters, connection
> > > >> | > info, size etc.
> > > >> | > resize: resize the file in the volume, refresh connections from initiator
> > > >> | > side
> > > >> | > List: List the connections
> > > >> | > Delete: logout the connections and delete the file in the gluster volume
> > > >> | >
> > > >> | > Couple of questions:
> > > >> | > 1. Should Block API have sub API's such as FileCreate, FileList,
> > > >> | > FileResize, File delete and etc then get it used in Block API as they
> > > >> | > mostly deal with files.
> > > >> | >
> > > >> |
> > > >> | IMO, Heketi should not expose any File related API. It should only have
> > > >> | APIs to service request for block devices; how the block devices are
> > > >> | created and modified is an implementation detail.
> > > >> |
> > > >> |
> > > >> | > 2. How do we create the actual file in the volume, meaning using FUSE
> > > >> | > mount (which may involve an extra process running) or gfapi, again if gfapi
> > > >> | > should we go with c API's, python bindings or go bindings ?
> > > >> | >
> > > >> | 3. Should we get targetcli related (LUN exporting) setup done from heketi
> > > >> | > or do we seek help from gdeploy for this ?
> > > >> | >
> > > >> |
> > > >> | I would prefer to either have it in Heketi or in Kubernetes. If the API in
> > > >> | Heketi promises just the creation of block device, then the rest of the
> > > >> | implementation should be in Kubernetes(the export part). If the API in
> > > >> | Heketi promises create and export both, I would say Heketi should have the
> > > >> | implementation within itself.
> > > >> |
> > > >> |
> > > >>
> > > >> IMO, we should not think about how the clients ( ex: k8s) use it, because there may be different clients.
> > > >> We should concentrate mainly on 'in/out' of block API in Heketi. Regardless of which client, the API should act the same way.
> > > >>
> > > >> --Humble
> > > >> _______________________________________________
> > > >> Gluster-devel mailing list
> > > >> Gluster-devel at gluster.org
> > > >> http://www.gluster.org/mailman/listinfo/gluster-devel
> > > >
> > > > _______________________________________________
> > > > Gluster-devel mailing list
> > > > Gluster-devel at gluster.org
> > > > http://www.gluster.org/mailman/listinfo/gluster-devel
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