CMS

Goals

• L-Store plugin for root, so that rootio can read (write?) L-Store files
• CMS then uses REDDnet as temporary storage for user analysis (Tier 3 and below)
• Other CMS Applications possible, begin with above.

Benchmarks

• IBP --> CMSSW streaming tests
  • CMSSW_1_2_0
  • input: 1.5GB root file, 100 events
  • ROOT/L plugin
    • extends TFile Class
    • Naive implementation
      • relays block requests directly from root
      • no blocksize specified in root (optimizing blocksize may reduce latency significantly)
      • no caching or read-ahead (also may reduce latency)
  • PING measures network latency
  • IPERF & File Download measures network bandwidth
• RUNNING ON VAMPIRE, 2GHz CPU:

Vanderbilt Campus has a 0.60 Gbit/s connection to outside

Data Source	# Depots (stripe)	URL	PING time (ms)	IPERF		File (lors) Download	CMSSW default (mins)
				in	out
local gpfs	0	/gpfs2/					11
Vanderbilt REDDnet Depots	10	vudepot1.accre.vanderbilt.edu	0.16				1.0
across campus IBP Depot	1	vpac12.phy.vanderbilt.edu	0.46				3.5
Remote IBP Depots	5	ounce.cs.utk.edu	13				20
		pound.cs.utk.edu	13
		acre.cs.utk.edu	13
		umich-depot01.ultralight.org	83
		ibp.its.uiowa.edu	35

• RUNNING AT CALTECH, 2.4GHz Opteron:

Caltech has 10 Gbit/s connection to Ultralight

Data Source	# Depots (stripe)	URL	PING time (ms)	IPERF		1.5GB File Download		CMSSW default (mins)	CMSSW >blksize (mins)
				in	out	time (m:s)	rate (Mbits/s)
local disk	0	/dev/hda3						1.0
Vanderbilt REDDnet depots	10	vudepot1.accre.vanderbilt.edu	78					100
U Mich REDDnet depots	2	umich-depot01.ultralight.org	63			4: 0	51	33
Caltech REDDnet depots	2	caltech-depot01.ultralight.org	0.60			0: 16	770	1.0
UT Knoxville IBP depot	1	acre.cs.utk.edu	93
U Iowa IBP depots	1	ibp.its.uiowa.edu	70

Current Work in Progress

• Figure out how to get necessary code included in CMSSW
  • Talk to Bill Tannenbaum, Phillipe Canal,...
  • include L-Store code in CMSSW distribution so it is built on platforms correctly for use with rest of CMS software.
  • that way no software for users to download themselves, no changing of configuratino scripts, etc.
  • how test and validate before checking in?
  • how to check code in?
• Figure out all issues needed to integrate with CMS data distribution model
  • phEDeX, TFILE, DBS/DLS,...
• Switch Root plugin to use L-Store version of libxio

Demos

Demos at March 2007 OSG Grid Meeting (UC San Diego)

Can use Vladimir's or Dmitri's analysis for all of below.

Interactive Root

• First upload a file to Depots spread across the WAN, use LORSView to show where and how they go.
• Then read it back in root, show it works.
• Mainly an introduction to the issues.

100 Node ACCRE Run

• each reads its own file from WAN set of depots.
• show speed versus local copies of file (data tethered analysis).

100 CPU Grid Job

• similar to ACCRE Run, each job reads its own file from WAN depots.
• jobs are distributed accross open science grid sites
• demonstrates complete lack of data tether.

To Do To Get Ready

• Run all of the above many times before actual demo!
• Get LORSview upload working
• Figure out how to submit 100 CPU Grid Job.
• Want to run all 100 ACCRE jobs simultaneously? Need to work with ACCRE on that...

Get Rick Cavanaugh to run his analysis

• need most of the stuff needed for "Summer 2007 demo" but maybe not all fully in place.
• he runs himself.
• work with him so he understands full functionality possible.
• work with him to develop ideas for better implementing Summer 2007 demo
  • what docs are needed
  • best approach to getting users using it
  • etc.

Summer 2007 Demo

• A "scratch space" demo for CMS users.
• Use deployed REDDnet resources which should become available June 2007
• Load REDDnet with "hot" data files, convince a few users to try them out
• Must have L-Store code fully integrated with CMS software

General Testing

verify ROOT/L works

• package up plugin for CMS L-Store test community
• gain experience via benchmarking
• finalize API (add write access?)
• checkin plugin to root cvs
  • it will take a while for this ROOT addition to propagate into CMSSW
• explore CMSSW procedures for checkin of LORS and/or LSTORE
  • it will take months for L-Store to be available for check-in

increasing level of stress tests:

(validate and benchmark)

do various combinations of the following:

• single jobs vs simultaneous jobs
• many jobs: at one cluster vs across the grid
• simultaneous jobs hitting same ibp depot accessing one or many files
• simultaneous jobs hitting same file at one depot or striped across many depots

Also need to benchmark and profile various types of jobs:

• I/O intensive skims
• CPU intensive jobs
• show benchmarks/demonstrate which jobs work well with L-Store and which jobs won't work well (if any). Have thorough benchmarks for the worst-case scenario.
• gather numbers to discuss impact on bandwidth as L-Store usage explodes.
• will people feel more free to do unnecessary computations?

assemble interactive analysis demos:

• host variety of interesting datasets
  • need to identify these datasets
• make a wiki
  • with instructions
  • links to necessary data catalogs
    • L-Store
    • DBS/DLS
• gather visually interesting ROOT Macros
  • event/detector displays
  • histograms/results
• any FW-lite tools (even development versions) to try

assist user-analysis batch production:

• identify and host a wide variety of datasets
  • calibration datasets
  • various backgrounds, pileup
  • variety of signal samples
• populate catalogs to find datasets
• web tools to assist this
  • how to find datasets
  • how to upload results
  • how to register results in catalogs
  • how to coordinate with L-Store and DBS/DLS

provide info on joining CMS/L (via L-Store? via REDDnet? ultralight?)

• how to add an ibp depot

Long Term Needs

• L-store version of libxio
• Stable, production REDDnet depot deployment
  • including request tracker support!
• L-store software fully integrated with CMS software, and being distributed.
  • this means need source code for L-Store version of libxio - check into CMS distribution

SRM interface

• in principle, this is important for CMS usage.
• Need to get new support person on board with this and up to speed.