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

[ronnie sahlberg]

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=0ahUKEwjChpba3PnXAhXBKZQKHQa9DEYQFggpMAA&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