Re: [Qemu-devel] iSER transport name is not good

[Charles Kelimod]

Hi Dave and Sahlberg,

for this type of name:iser://<host>/<iqn>/<lun>, I completely agree with
you.
my issue is when I create an vm from libvirt, the qemu command line should
be:
-drive
file.driver=iser,file.portal=xx.xx.xx.xx:3260,file.target=iqn.xxx,file.lun=0,file.transport=iser

Actually "iser" is added by me in libvirt, which can work by a little
modification. But I think file.transport=rdma would be better, as I think
iser is protocol, and rdma is transport, and libvirt defined it, if I added
a new transport name (iser) in libvirt, it will be confusable.

Best Regards,
Charles.

On Fri, Dec 8, 2017 at 2:07 PM, ronnie sahlberg <address@hidden>
wrote:

> David,
>
> Yes, QEMU has supported iSER (iSCSI extensions for RDMA) via a
> userspace library, libiscsi, since about a year.
> Here is a nice presentation from the developer of iSER support :
> https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=
> web&cd=1&cad=rja&uact=8&ved=0ahUKEwjChpba3PnXAhXBKZQKHQa9D
> EYQFggpMAA&url=https%3A%2F%2Fwww.snia.org%2Fsites%2Fdefault%2Ffiles%2FSDC%
> 2F2016%2Fpresentations%2Fstorage_networking%2FShterman-Grimberg_Greenberg_
> Performance%2520Implications%2520Libiscsi_%2520RDMA_V6.pdf&usg=
> AOvVaw3xyvdIciRKVprboN6rClTA
>
> In QEMU, you use it the same way as you would use the userspace iSCSI
> support which has been in QEMU for quite a long time.
> The only difference is that instead of providing a
> iscsi://<host>/<iqn>/<lun> you select iSER by specifying an url of the
> form
> iser://<host>/<iqn>/<lun>
>
>
> I.e. the only difference is the protocol part of the URL. When QEMU
> passes this URL to libiscsi, it allows the library to decide on
> whether to use normal iSCSI or whether it should use iSER.
>
> I think RDMA would be a less good name for this as RDMA is not only
> used to transport iSCSI but is also used for NFS as well as SMB.
>
>
>
> regards
> ronnie sahlberg
>
>
> On Fri, Dec 8, 2017 at 4:41 AM, Dr. David Alan Gilbert
> <address@hidden> wrote:
> > * Charles Kelimod (address@hidden) wrote:
> >> Hello,
> >>
> >>
> >> I'm on the road of modifying libvirt to add iSER support, and I found
> qemu
> >> is actually support that. But, the transport name is iSER, which should
> be
> >> RDMA and there libvirt already defined it.
> >>
> >> Best Regards,
> >> Charles.
> >
> > Hi Charles,
> >   So this is iSCSI extensions for RDMA?  I've cc'd in the qemu iSCSI
> > maintainers.
> >   Can you just explain what you're seeing libvirt do and what you think
> > qemu is expecting it to do for iSER?
> >
> > Dave
> >
> > --
> > Dr. David Alan Gilbert / address@hidden / Manchester, UK
>