Re: [LSF/MM TOPIC] Remote access to pmem on storage targets

[Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

> On Jan 26, 2016, at 10:25 AM, Atchley, Scott <atchleyes-1Heg1YXhbW8@public.gmane.org> wrote:
> 
>> On Jan 25, 2016, at 4:19 PM, Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> wrote:
>> 
>> I'd like to propose a discussion of how to take advantage of
>> persistent memory in network-attached storage scenarios.
>> 
>> RDMA runs on high speed network fabrics and offloads data
>> transfer from host CPUs. Thus it is a good match to the
>> performance characteristics of persistent memory.
>> 
>> Today Linux supports iSER, SRP, and NFS/RDMA on RDMA
>> fabrics. What kind of changes are needed in the Linux I/O
>> stack (in particular, storage targets) and in these storage
>> protocols to get the most benefit from ultra-low latency
>> storage?
>> 
>> There have been recent proposals about how storage protocols
>> and implementations might need to change (eg. Tom Talpey's
>> SNIA proposals for changing to a push data transfer model,
>> Sagi's proposal to utilize DAX under the NFS/RDMA server,
>> and my proposal for a new pNFS layout to drive RDMA data
>> transfer directly).
>> 
>> The outcome of the discussion would be to understand what
>> people are working on now and what is the desired
>> architectural approach in order to determine where storage
>> developers should be focused.
>> 
>> This could be either a BoF or a session during the main
>> tracks. There is sure to be a narrow segment of each
>> track's attendees that would have interest in this topic.
>> 
>> --
>> Chuck Lever
> 
> Chuck,
> 
> One difference on targets is that some NVM/persistent memory may be byte-addressable while other NVM is only block addressable.
> 
> Another difference is that NVMe-over-Fabrics will allow remote access of the target’s NVMe devices using the NVMe API.

As I understand it, NVMf devices look like local devices.
NVMf devices need globally unique naming to enable safe use
with pNFS and other remote storage access protocols.

--
Chuck Lever




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