I think (and I won't be wrong) you can have better performance with native
xrootd (since you forget about other elements slowing down the system). Maybe
for some Tier3 that would be the case (those far away from it's Tier2), but
at least for us it's not realistic. We're speaking of hundreds of Terabytes
and many access methods (srm, gsiftp...) and I don't think a native xrootd
cluster is about that.
On Wednesday 20 February 2008 13:27, Fabrizio Furano wrote:
> Hi Pablo,
> I see your point. I was mentioning the orthodox xrootd anyway, not the
> xrootd door, which from my point of view is just an emulation. After
> all, this is the xrootd mailing list :-D
> For lustre I am not an expert, from a pure functional standpoint you
> can put an xrootd server exporting the lustre mountpoints I guess. In
> that case you will not go beyond the lustre performance of course.
> Pablo Fernandez ha scritto:
> > Thanks!
> > Unfortunately the xrootd protocol does not work as expected in dcache.
> > The idea was to use a conventional SE to store all the data for Tier2 and
> > also serve files to the Tier3... I don't know if Lustre implements an
> > xrootd door as well, maybe in a few months I'll try that.
> > BR/Pablo
> > On Wednesday 20 February 2008 11:40, Fabrizio Furano wrote:
> >> Hi Pablo,
> >> that's very interesting, and I agree completely with your conclusion,
> >> i.e. in most cases the lan data access is more efficient and scales
> >> better with respect to local disk access. Many times this is not very
> >> well understood by people, always striving to keep local files at any
> >> cost.
> >> It would be very interesting to have a comparison between the
> >> performance in proof between a dcache storage and an analogous xrootd
> >> storage, which is the default solution for that. With the same pool of
> >> workers of course.
> >> From what I've understood, dcache uses a read ahead mechanism (at the
> >> client side), while xrootd uses a scheme which is mixed with informed
> >> async prefetching.
> >> Fabrizio
> >> Pablo Fernandez ha scritto:
> >>> Hi all,
> >>> I would like to share with you some information about my testings of
> >>> performance in Proof with different storage schemas.
> >>> http://root.cern.ch/phpBB2/viewtopic.php?t=6236
> >>> I have translated this topic to the Proof Forum since seems to me more
> >>> Proof-related than just xrootd, I hope you don't mind.
> >>> BR/Pablo
Pablo Fernandez Fernandez e-mail: [log in to unmask]
Dpto Fisica Teorica. C-XI.
Facultad de Ciencias
Universidad Autonoma de Madrid. Phone: 34 91 497 3976
Cantoblanco, 28049 Madrid, Spain. Fax: 34 91 497 4086