Re: [Scst-devel] SRP vs iSER

[Aaron K. <aar...@na...>]

Thanks everyone for your feedback!

-Aaron

On 11/4/15 9:02 AM, Ariel Nahum wrote:
> Hi Aaron and Sebastian.
> Including responses to both of your emails.
>
>  > Mellanox mostly cares for iSER.
> Mellanox cares for all RDMA protocols, srp included. if you follow the
> Linux-rdma mailing list you will see that our guys are very much
> involved in code review and bug fixes in the ib_srp driver (which is led
> by the great Bart).
> And in addition, Mellanox is leading the iser initiator and target
> development.
>
> Aaron, in your decision you might consider the following:
> - iSER supports IB and RoCE (and RoCEv2) while SRP relies on the SM (IB
> only)
> - iSER support T10-DIF data integrity offload where SRP has yet to
> - iSER as an iSCSI extension inherits authentication protocols such as
> CHAP which does not exist in SRP, plus have all the advantages of being
> an iSCSI protocol.
>
> The two protocols are very similar and comparable in terms of stability
> and performance.
> So the decision basically depends on what you are looking for and your
> preferences/comfort.
>
> Greetings to all,
> Ariel
>
>
>
> On 11/2/2015 11:29 AM, Sebastian Parschauer wrote:
>> Hi Aaron,
>>
>> Mellanox mostly cares for iSER. The SRP implementation in MLNX_OFED
>> differs from the upstream kernel implementation. Personally I like the
>> upstream SRP implementation more.
>>
>> The biggest advantage of SRP over iSER is that it is RDMA-only and can
>> be kernel-only. With Bart developing the target and the initiator side,
>> everything comes out of one hand and fits perfectly together.
>>
>> iSER relies on user-space and IPoIB. IPoIB is quite complex and there is
>> a lot that can go wrong in that driver.
>>
>> Simplicity is often good for stability. This is why we at ProfitBricks
>> prefer SRP.
>>
>> Cheers,
>> Sebastian
>>
>>
>> On 31.10.2015 20:05, Knister, Aaron S. (GSFC-606.2)[COMPUTER SCIENCE
>> CORP] wrote:
>>> Hi Everyone,
>>>
>>> I've been using SRP for a storage project I'm working on.  Thanks to
>>> some great help from Bart I've been able to get really great performance
>>> with SRP and my application (GPFS). Elsewhere in our org folks are using
>>> iSER also with great success and performance.  I've been asked about
>>> iSER vs SRP and which one I should be using but I couldn't come up with
>>> a great answer. I'm more comfortable with SRP and it seems
>>> marginally easier to configure and use than iSER but other than that I
>>> think it's a toss up.
>>>
>>> Does anyone have insight into SRP vs iSER and why I would/should use one
>>> over the other? Are there significant drawbacks advantages to one over
>>> the other? From a support perspective we are Mellanox customers, does
>>> that factor in at all? I believe mellanox has contributed significantly
>>> to the ib_srpt driver, is the same true of iSER?
>>>
>>> Many thanks!
>>>
>>> -Aaron
>>
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-- 
Aaron Knister
NASA Center for Climate Simulation (Code 606.2)
Goddard Space Flight Center
(301) 286-2776