EIC/BNL Computing discussion

[Jerome LAURET <jeromel AT bnl.gov>]

        Because ATLAS has more than one server? :-)

On 2021-04-15 13:41, Torre Wenaus via Eic-bnl-comp-l wrote:
> Hi Jerome,
> RACF has supported XRootD for ATLAS for many years. Why is this 
> capability and experience not readily transferable to EIC? Isn't that 
> one benefit of a unified facility? Is EIC somehow bound to using storage 
> that is not (without work) XRootD capable, and if so, why?
>    Torre
>
> On Thu, Apr 15, 2021 at 12:45 PM Jerome LAURET via Eic-bnl-comp-l 
> <eic-bnl-comp-l AT lists.bnl.gov <mailto:eic-bnl-comp-l AT lists.bnl.gov>> wrote:
>
>
>              Greetings,
>
>              As you know, several detector proto-collaboration are starting
>     and without saying anything on who can/should use what, a discussion
>     was carried with a few parties as per providing a Pbytes of storage
>     for incoming work. Xrootd was noted as desired by some but in all,
>     there are a few logistic issues at BNL I would like to summarize
>     here.
>
>     A reminder - there is 1 PBytes of storage accessible through an
>     S3 protocol and interface (lustre storage below). "S3" is the
>     equivalent the Amazon S3 storage ; it allows access read and write
>     to a global (world accessible) storage using a thin client interface
>     (and no further requirements). But you need to imagine this as
>     a "put and get" (good for large dataset upload / downloads or
>     move data there once not needed on "live" direct access storage).
>     This is a SINGLE JBOD [just a bunch of disks] and a single server
>     so there are limitations here ... Xrootd has a documented CEPH
>     object  storage interface but no plugin we can find for S3 alone
>     (if someone knows of one, please LUK). CEPH works best with
>     a bunch of servers (not a single one ; emulating many servers
>     with VMs would cut the performance by 1/3rd). S3 is happy
>     with a single decent server and would provide the current
>     JBOD/Luster performance (ideal 3-4 GB/sec).
>
>     We discussed the options moving forward with Kolja (and others)
>
>     - XrootD does not seem to be a realistically fast solution
>         (because it would need CEPH for immediate availability,
>         CEPH would work if multiple servers are available but we
>         do not have the infrastructure for it)
>
>     - Lustre FS (POSIX) would feel like what we have now on gpfs02
>         for the EIC work
>
>     - S3 takes a bit of extra work to learn the interface from a
>         end-user perspective but has the advantage of allowing seamless
>         sharing between labs and other places (external and international
>         collaborators with NO oher work needed)
>
>
>     Through our iterative discussions of use-cases and scope, we came
>     to the conclusions that the best is for now to either:
>     - Leave S3, continue to try Xrootd on top [even if development
>         is needed continue the effort but no ETA]
>
>     - Remount the storage Lustre onl,. no S3
>
>
>     The two paths depends on whether we would have remote contributors or
>     not. Feedback from IP6 tend to indicate remote users (i.e. people
>     from other institutions providing simulation support on external
>     CPU resources ... they could upload the results securely to S3
>     from remote and everyone could download).
>
>              Further comments welcomed.
>
>
>     -- 
>                    ,,,,,
>                   ( o o )
>                --m---U---m--
>                    Jerome
>                 <he-him-his>
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>
>
>
> --
> -- Torre Wenaus, BNL NPPS Group, ATLAS Experiment
> -- BNL 510A 1-222 | 631-681-7892 | wenaus AT gmail.com 
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--
             ,,,,,
            ( o o )
         --m---U---m--
             Jerome
          <he-him-his>