CMS staging from tape Natalia Ratnikova, Fermilab for WLCG pre-GDB Storage meeting CERN, 12 September 2017

Outline CMS data organization Data transfers workflow CMS storage sites topology CMS local staging and transfers details Staging tests status and work in progress 9/12/17 Natalia Ratnikova | WLCG pre-GDB Storage | CMS staging from tape

CMS data organization … CMS data are organized into datasets by physics content Dataset size varies: 0.1 - 100 TB Within a dataset, files are organized into blocks of 1–1000 for scalability Small files are merged after processing to help scalability of storage and catalogs Typical file size is ~ 2.5 G, but there are some quite large files CMS data management tools can manipulate individual blocks as well as full dataset. Data transfers are driven by subscribing datasets or blocks to the Files … Dataset Blocks 9/12/17 Natalia Ratnikova | WLCG pre-GDB Storage | CMS staging from tape

Data transfers workflow Powered by PhEDEx: FTS3 Client GFAL Site Agents 9/12/17 Natalia Ratnikova | WLCG pre-GDB Storage | CMS staging from tape

CMS storage sites topology CMS uses tape storage at 8 sites: T0_CH_CERN T1_US_FNAL T1_DE_KIT T1_RU_JINR T1_ES_PIC T1_IT_CNAF T1_FR_CCIN2P3 T1_UK_RAL During Run 1 CMS data needed for production at Tier-1 sites have been pre-staged manually by the site admins. After Run1 all CMS Tier-1s sites deployed separate endpoints for disk and tape storage Tape storage is used mainly for archiving purpose. Data needed for production are subscribed to Disk by the production operators/tools. 9/12/17 Natalia Ratnikova | WLCG pre-GDB Storage | CMS staging from tape

CMS local staging and transfers details Data are routed from the available sources to the destination, taking into account the link costs, performance and subscription priorities, using priority-window up to a fixed data volume. Sites are using FTS3 as a transport layer to download the routed data. T0/T1 sites run a special local Stager agent to check for data routed from MSS, call local plugins to stage the files and check the status, and mark the staged files as available for the download. Routing, staging, and download are performed asynchronously. 9/12/17 Natalia Ratnikova | WLCG pre-GDB Storage | CMS staging from tape

Staging tests status and work in progress Performed by CMS data operations to test the throughput between T1 MSS/Buffer abd T1 Disk end points the throughput goals reached too many tape mounts reported by the sites fine tuning of the agents configuration to increase the number of staging requests and let MSS system to optimize Triple increase of the router priority windows adjustments on the MSS system side experimenting with the stager idle time to create larger request volume All detailed info is only in the local stager logs: experimenting with FTS3 staging to benefit from central monitoring. 9/12/17 Natalia Ratnikova | WLCG pre-GDB Storage | CMS staging from tape