As of 25 April 2006... Condor Worldwide: –56,682 CPUs / ??? TB / 1758 sites Teragrid –15,328 CPUs / 220 TB / 6 sites Open Science Grid –21,156 CPUs / 83 TB / 61 sites EGEE Grid –Lots??? http://www.cs.wisc.edu/condor/map Plentiful Computing Power
Complex Ecology of Storage Shared Filesystem shared disk shared disk private disk private disk private disk private disk HTTP, FTP, RFIO, gLite, SRB, SCP, RSYNC, HTTP... Independent Cluster Disks
Problems Accessing Data Large Burden on the User –User may not be able/willing to state files in advance. –Different services/protocols available at different sites. –Programs not modified to take advantage of services. Different access modes for different purposes. –File transfer: preparing system for intended use. –File system: access to data for running jobs. Resources go unused. –Disks on each node of a cluster. –Unorganized resources in a department/lab. –Would like to combine disks into larger structures. A global file system can’t satisfy everyone! –(Global means different things to different people.) –Both a technical and social problem.
What’s the Problem? We often assume that the site administrator is responsible for making the site comfortable for the user. (Not possible on the grid!) Rather, the user should be able to bring along a mechanism to access multiple independent (remote?) data sources. Of course, we have to make it easy!
Tactical Storage Systems (TSS) A TSS allows any node to serve as a file server or as a file system client. All components can be deployed without special privileges – but with security. Users can build up complex structures. –Filesystems, databases, caches,... –Admins need not know/care about larger structures. Two Independent Concepts: –Resources – The raw storage to be used. –Abstractions – The organization of storage.
file transfer file system file system file system file system file system file system file system Simple Filesystem App Distributed Database Abstraction Parrot App Distributed Filesystem Abstraction Parrot App Cluster administrator controls policy on all storage in cluster UNIX Workstations owners control policy on each machine. file server file server file server file server file server file server file server UNIX ??? Parrot 3PT
Key Properties Tactical Storage is Simple: –Appears as an ordinary filesystem. –Applies to unmodified applications and data w/out code changes, relinking, kernel modules, etc... Tactical Storage is Secure: –Authentication with standard GSI or Kerberos. –Rich distributed access control system. Tactical Storage is Semantic: –Name data by meaning, not by location. –Supports external name resolution mechanisms.
Access Control in File Servers Unix Security is not Sufficient –No global user database possible/desirable. –Mapping external credentials to Unix gets messy. Instead, Make External Names First-Class –Perform access control on remote, not local, names. –Types: Globus, Kerberos, Unix, Hostname, Address Each directory has an ACL: globus:/O=NotreDame/CN=DThain RWLA kerberos:firstname.lastname@example.org RWL hostname:*.cs.nd.edu RL address:192.168.1.* RWLA
file system file system file system file system file system file system file system UNIX file server file server file server file server file server file server file server Physics Group List Chemistry Group List Lab 5 Group List App data ACL: Lab 5 RW Chemistry R App data ACL: Physics RW Lab 5 R Distributed Group ACLs
Semantic Data Access Appl Parrot /usr/local = /chirp/host5.nd.edu/software /tmp = /chirp/host9.nd.edu/scratch /data = /gsiftp/ftp.nd.edu/mydata /db = resolver:find_db host5host9FTP /usr/local /tmp /data find_db Where is /db/dir/523? It’s at /ftp/ftp.infn.it/db/xz
Remote Database Access script Parrot file server file system DB data libdb.so sim.exe WAN Simple FS HEP Simulation Needs Direct DB Access –App linked against Objectivity DB. –Objectivity accesses filesystem directly. –How to distribute application securely? Solution: Remote Root Mount via Parrot: parrot –M /=/chirp/fileserver/rootdir parrot –M /=/chirp/fileserver/rootdir DB code can read/write/lock files directly. DB code can read/write/lock files directly. GSI Auth GSI Credit: Sander Klous @ NIKHEF
Remote Application Loading appl Parrot HTTP server file system liba.so libb.so libc.so Credit: Igor Sfiligoi @ Fermi National Lab HTTP Modular Simulation Needs Many Libraries –Devel. on workstations, then ported to grid. –Selection of library depends on analysis tech. –Constraint: Must use HTTP for file access. Solution: Dynamic Link with TSS+HTTP: –/home/cdfsoft -> /http/dcaf.fnal.gov/cdfsoft select several MB from 60 GB of libraries proxy
Technical Problem HTTP is not a filesystem! (No directories) –Advantages: Firewalls, caches, admins. Appl Parrot HTTP Module HTTP Server root etchomebin alicecmsbabar opendir(/home) GET /home HTTP/1.0
Technical Problem Solution: Turn the directories into files. –Can be cached in ordinary proxies! –Hierarchical SHA1 integrity check. Appl Parrot HTTP Module HTTP Server root etchomebin alicecmsbabar opendir(/home) GET /home/.dir HTTP/1.0.dir make httpfs alice babar cms
Logical Access to Bio Data Many databases of biological data in different formats around the world: –Archives: Swiss-Prot, TreMBL, NCBI, etc... –Replicas: Public, Shared, Private, ??? Users and applications want to refer to data objects by logical name, not location! –Access the nearest copy of the non-redundant protein database, don’t care where it is. Solution: EGEE data management system maps logical names (LFNs) to physical names (SFNs). Credit: Christophe Blanchet, Bioinformatics Center of Lyon, CNRS IBCP, France http://gbio.ibcp.fr/cblanchet, Christophe.Blanchet@ibcp.fr
Logical Access to Bio Data BLAST Parrot RFIOgLiteHTTPFTP Chirp Server FTP Server gLite Server EGEE File Location Service Run BLAST on LFN://ncbi.gov/nr.data open(LFN://ncbi.gov/nr.data) Where is LFN://ncbi.gov/nr.data? Find it at: FTP://ibcp.fr/nr.data nr.data RETR nr.data open(FTP://ibcp.fr/nr.data)
Expandable Filesystem for Experimental Data Credit: John Poirer @ Notre Dame Astrophysics Dept. buffer disk 2 GB/day today could be lots more! daily tape daily tape daily tape daily tape daily tape 30-year archive analysis code Can only analyze the most recent data. Project GRAND http://www.nd.edu/~grand
Expandable Filesystem for Experimental Data Credit: John Poirer @ Notre Dame Astrophysics Dept. buffer disk 2 GB/day today could be lots more! daily tape daily tape daily tape daily tape daily tape 30-year archive Project GRAND http://www.nd.edu/~grand file server file server file server file server Distributed Shared Filesystem Adapter analysis code Can analyze all data over large time scales.
Current Work Credit: Jesus Izaguirre and Aaron Striegel @ Notre Dame Now that we can easily use any storage... –Much easier to arrange data/jobs arbitrarily. –Idea: combine cluster storage / cluster comp! –Goal: keep jobs close to data that they need. –PINS: Processing in STorage Example: GEMS Distributed Databank –Facility for creating, storing, and analyzing molecular dynamics data in a cluster. –Goal: Be able to easily scale both CPU and storage capacity by adding commodity nodes.
file system file system file system file system file system file system file system UNIX file server file server file server file server file server file server file server meta-data database J1J2J3J4 D1D2D3D4D1 D3D4 F F(D1) Fetch D1 Compute F(D1) Query (Mol==“CH4”) && (T>300K) Distributed Filesystem Abstraction Adapter App D2D3D4 D2D3 D4 D1
More Open Problems Resource Management –How to prevent overcommitment -> badput? Security –How to easily express complex policies for sharing and controlling combined cpu/disk? Reliability –How to deal with disconnection, erasure, rejection, unexpected performance, etc... Garbage Collection –What’s to prevent me from filling every disk everywhere with computations that I might need? Debugging –How do we dig out of numerous, noisy, distributed logs that state relevant to a complex workflow?
Conclusion Tactical storage allows end users to build large structures out of simple building blocks without getting stuck on the ugly details.
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