1. dCache/SRM @ OSG Abhishek Rana Frank Würthwein UCSD

2. OSG@UCSD 12/16/04 Frank Würthwein2 SRM-dCache @ fnal 40GB/hour CMS write/hour this week CDF reads/day this year 20TB/day

3. OSG@UCSD 12/16/04 Frank Würthwein3 CDF Center @ FNAL For comparison: Tier-1 requirement as Specified in CMS Computing model is 800MB/sec A day in 2003 Typical month in 2004 900MB/s

4. OSG@UCSD 12/16/04 Frank Würthwein4 SRM-dCache scalability IO scalability is essentially infinite. –Depends primarily on # of pools and IO per pool. Scalability limits lie elsewhere: –Large rate of client requests Tight loops that try to open many files will bring system into its knees. –Large rate of metadata accesses Limit # of files per directory Do not allow user access to virtual filesystem Applications need to avoid “stupid” behavior!

5. OSG@UCSD 12/16/04 Frank Würthwein5 The “geek gap” SRM-dCache is as complex as it is powerful. –Requires well packaged “cookie cutter” configurations to minimize knowledge required from site admins. –Requires some thought about hardware: How much infrastructure hardware per cluster? Choose filesystem that doesn’t fragment. Choose linux kernel that isn’t buggy. Some performance tuning (p2p, cost function, “quotas”)

6. OSG@UCSD 12/16/04 Frank Würthwein6 Deployed flavors As cache for mass storage (HPSS,Enstore,OSM, …) Virtualizing space on RAID servers – replication only for load balancing Virtualizing compute node space –N copies of every file; “lazy” replication –virtual RAID in addition to load balancing.

7. OSG@UCSD 12/16/04 Frank Würthwein7 FNAL plans Space reservation & quotas authorization module MIS Integration, deployment, operations

8. OSG@UCSD 12/16/04 Frank Würthwein8 Reservations & Quotas Quota exists as a hard partitioning of pools and types of files that may be loaded into those pools. SRM v2 type reservations are being retrofitted into SRM v1.1 by 3/2005.

9. OSG@UCSD 12/16/04 Frank Würthwein9 Security & ACLs Cron based synch of dcache & VOMS exists today. Authorization module with callout to GUMS by 3/2005

10. OSG@UCSD 12/16/04 Frank Würthwein10 MIS Interface to GRIS & GIIS works Plan of Action being developed by 2/2005. –Internal accounting schema must allow efficient queries. –Must allow VO specific queries –Send info to MonALISA

11. OSG@UCSD 12/16/04 Frank Würthwein11 Integration, deployment, operations ~1/2005: Deploy resilient dCache at CMS sites & start operations challenge from Tier-1 to Tier-2. (UCSD will allow some VOs on part of its cluster) ~3/2005: Re-deploy new version incl. reservations, security, MIS enhancements.

12. OSG@UCSD 12/16/04 Frank Würthwein12 Concerns by fkw Application’s use of SRM-dCache –dCache specific scalability issues –“Expectation management” Devil’s in the details –Personally, I would proceed well planned & carefully integrate a few sites at a time rather than a large free for all.