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Hi Pablo, Actually, we (as well as other sites) do exactly what you say -- run hundreds of terabytes with multiple access methods (xroot prefered because it scales the best). We'e been doing that for years. So, I don't understand why you think that it's not about that. Andy ----- Original Message ----- From: "Pablo Fernandez" <[log in to unmask]> To: "Fabrizio Furano" <[log in to unmask]> Cc: <[log in to unmask]> Sent: Wednesday, February 20, 2008 7:05 AM Subject: Re: Proof performance with different storage schemas > Hi Fabrizio, > > 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. > > Regards, > Pablo > > > > 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. >> >> Fabrizio >> >> 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 > ============================================================================== >