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FYI, and some of us (Andy, me and possibly even Wilko) will likely have to spend time dealing with it. -- Wei Yang | [log in to unmask] | 650-926-3338(O) ________________________________ From: Rob Gardner [mailto:[log in to unmask]] Sent: Friday, August 15, 2008 11:15 AM To: Alain Roy; Yang, Wei; Tanya Levshina; Ted Hesselroth Cc: Ruth Pordes; Michael Ernst; Rob Gardner; Andrew Hanushevsky; Alex Sim Subject: Re: Bestman-xrootd documentation, installation Notes from today's meeting on Bestman, Bestman-Xrootd, and Xrootd integration in VDT. Comments/corrections welcomed. regards, Rob -------------------------------------------------------------------- Attending: Wei, Rob, Tanya, Ted, Alain Overview discussion ============== We discussed the requests from ATLAS for including "bestman-xrootd in VDT", and expectations for OSG-Storage. There was general agreement this consists in three parts, and we finally I think cleared up problems with the nomenclature: 1) Bestman, which provides an SRM endpoint to Posix file systems. 2) Xrootd - the storage system itself 3) Three pieces needed to connect Bestman to Xrootd which are: XrootdFS, FUSE, and XrdCNS. Bestman-Xrootd was (is) an separate implementation of Bestman developed by LBL(Alex) and SLAC(Wei) specifically to meet ATLAS requirements though the resulting product is completely generic. It is a subset of the full Bestman, and does not support space token reservations in the most general sense. It does implement a concept of static space tokens. It is also 10 times faster handling SRM requests. More info here: http://wt2.slac.stanford.edu/xrootdfs/bestman-xrootd.html Bestman-Xrootd has been integrated into the original Bestman, and now is available as a configuration option of Bestman called "Bestman-Gateway". This is not yet in VDT. Xrootd is already in VDT, though its an older version. The key pieces for integrating a new Bestman to Xrootd are XrootdFS, FUSE and XrdCNS. This is where most of the questions, from the point of view of OSG-Storage, arise. XrootFS is a package that Wei wrote which implements a number of Unix file system commands for the files in xrootd in a Posix-like way that Bestman deal with, see http://wt2.slac.stanford.edu/xrootdfs/xrootdfs.html. This is done using FUSE, http://fuse.sourceforge.net/, which comes with Scientific Linux 4, 4.5, 5 but otherwise can be installed by admins from the website, and also XrdCNS. It was agreed to best let admins handle the FUSE piece themselves but provide pointers as appropriate. XrdCNS - the service which provides a composite namespace (a directory of shadow files for all of the files in an xrootd system) is needed by XrootdFS and is currently provided separately from xrootd. Wei says this will eventually be part of the standard xrootd release, in a few weeks time. For now it was agreed to provide a package for it in VDT. Packaging + Configuration ================== We discussed what makes sense here - it was agreed to start simply, using the VDT as an integration point for all the components except FUSE: latest Bestman, xrootd, and the integration piece (XrootdFS and for now XrdCNS). OSG-Storage will have further discussion and consideration of the main packaging approach, rpm vs pacman. How a complete system gets deployed is a major consideration from the start. Like dCache, a number of servers will typically be required and what bits get installed on each depends on its role. Configuration does not necessarily need to be fully scripted, and indeed this is not practical given the complexity. It was agreed that based on test-stand experiences by OSG-Storage (and later by VTB) general guidelines would be provided for assigning roles and installing & configuring packages. It was agreed to start out simple and to organize packages to allow maximum flexibility for various types of sites. Again, the storage team felt more experience was needed here, and will be in contact with Wei regarding recommended config options for the test-stand. Support ====== We discussed a bit the expectations for support, what it really means. From a high level I said ATLAS expects these components to be treated as 'first class citizens' in the OSG storage group along the same lines as dCache. Expanding for the minutes here, I think this means, for example, providing the integrated set of components that site admins can install from a single reference point: packages in VDT as appropriate, institutionalizing install procedures, and to provide the OSG liaison to the Bestman and xrootd projects as appropriate when dealing with integration problems or software bugs. (It does not mean fully automating an installation which is likely too difficult in the general case I think). Regarding testing, I will ask the OSG Integration group to use the VTB to test candidate releases, as we have done with the dCache SE and other services in OSG. On Aug 14, 2008, at 1:17 PM, Rob Gardner wrote: Alain, thanks. Can everyone confirm the following for a meeting tomorrow: 11 CDT Phone: (605) 475-6000, Access code: 735188 Agenda will be to talk through Wei's points focusing specifically on VDT integration and installation issues/dependencies. thanks, Rob On Aug 14, 2008, at 1:12 PM, Alain Roy wrote: I think it's a good idea, and that time is fine with me. Just let me know the coordinates. -alain On Aug 14, 2008, at 10:58 AM, Rob Gardner wrote: cc'ing Alain here - I think smaller meeting might be very useful. Does everyone agree? If so how about tomorrow at 11 am CDT? (I can setup the phone) regards, Rob On Aug 14, 2008, at 12:42 PM, Wei Yang wrote: Hi Rob, I was not in that meeting but Alex Sim forwarded something to me, and I e-mailed back to Tanya saying that xrootdfs is still needed despite the issue of FUSE kernel module. Let me know if you want me to schedule a meeting with Alain, Tanya? I don't have Alain's e-mail address though I receive e-mails from him almost every week:-) regards, Wei Yang | [log in to unmask] | 650-926-3338(O) Rob Gardner wrote: Hi Wei Let me chat first with Alain. I noticed b-m, xrootd was discussed heavily in yesterday's osg-storage meeting. Perhaps you're already in contact with Tanya? I don't want to create more noise, but it seemed to me a meeting between you guys and OSG (specifically Alain and Tanya) would be helpful to get answers to your questions. Rob