[Gluster-users] Network Block device (NBD) on top of glusterfs

Vijay Bellur vbellur at redhat.com
Mon Mar 25 06:36:46 UTC 2019

Hi Xiubo,

On Fri, Mar 22, 2019 at 5:48 PM Xiubo Li <xiubli at redhat.com> wrote:

> On 2019/3/21 11:29, Xiubo Li wrote:
> All,
> I am one of the contributor for gluster-block
> <https://github.com/gluster/gluster-block>[1] project, and also I
> contribute to linux kernel and open-iscsi <https://github.com/open-iscsi>
> project.[2]
> NBD was around for some time, but in recent time, linux kernel’s Network
> Block Device (NBD) is enhanced and made to work with more devices and also
> the option to integrate with netlink is added. So, I tried to provide a
> glusterfs client based NBD driver recently. Please refer github issue #633
> <https://github.com/gluster/glusterfs/issues/633>[3], and good news is I
> have a working code, with most basic things @ nbd-runner project
> <https://github.com/gluster/nbd-runner>[4].
This is nice. Thank you for your work!

> As mentioned the nbd-runner(NBD proto) will work in the same layer with
> tcmu-runner(iSCSI proto), this is not trying to replace the
> gluster-block/ceph-iscsi-gateway great projects.
> It just provides the common library to do the low level stuff, like the
> sysfs/netlink operations and the IOs from the nbd kernel socket, and the
> great tcmu-runner project is doing the sysfs/uio operations and IOs from
> the kernel SCSI/iSCSI.
> The nbd-cli tool will work like the iscsi-initiator-utils, and the
> nbd-runner daemon will work like the tcmu-runner daemon, that's all.

Do you have thoughts on how nbd-runner currently differs or would differ
from tcmu-runner? It might be useful to document the differences in github
(or elsewhere) so that users can make an informed choice between nbd-runner
& tcmu-runner.

In tcmu-runner for different backend storages, they have separate handlers,
> glfs.c handler for Gluster, rbd.c handler for Ceph, etc. And what the
> handlers here are doing the actual IOs with the backend storage services
> once the IO paths setup are done by ceph-iscsi-gateway/gluster-block....
> Then we can support all the kind of backend storages, like the
> Gluster/Ceph/Azure... as one separate handler in nbd-runner, which no need
> to care about the NBD low level's stuff updates and changes.

Given that the charter for this project is to support multiple backend
storage projects, would not it be better to host the project in the github
repository associated with nbd [5]? Doing it that way could provide a more
neutral (as perceived by users) venue for hosting nbd-runner and help you
in getting more adoption for your work.


[5] https://github.com/NetworkBlockDevice/nbd

> Thanks.
> While this email is about announcing the project, and asking for more
> collaboration, I would also like to discuss more about the placement of the
> project itself. Currently nbd-runner project is expected to be shared by
> our friends at Ceph project too, to provide NBD driver for Ceph. I have
> personally worked with some of them closely while contributing to
> open-iSCSI project, and we would like to take this project to great success.
> Now few questions:
>    1. Can I continue to use http://github.com/gluster/nbd-runner as home
>    for this project, even if its shared by other filesystem projects?
>    - I personally am fine with this.
>    1. Should there be a separate organization for this repo?
>    - While it may make sense in future, for now, I am not planning to
>    start any new thing?
> It would be great if we have some consensus on this soon as nbd-runner is
> a new repository. If there are no concerns, I will continue to contribute
> to the existing repository.
> Regards,
> Xiubo Li (@lxbsz)
> [1] - https://github.com/gluster/gluster-block
> [2] - https://github.com/open-iscsi
> [3] - https://github.com/gluster/glusterfs/issues/633
> [4] - https://github.com/gluster/nbd-runner
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