The Vault Data Manager

Derek Hower2/10/2011

Summary• This talk:

– Is: A Conceptual overview & discussion– Is not: A Vault tutorial– Is not: Polished. Interruptions will hide that.

• Vault unifies:– Data storage– Data analysis– Job management

• Features:– Designed for flexibility & sharing– Should be sufficient to meet NSF guidelines

• Proposal (open to discussion): – The group should phase-in Vault

Outline• Elephants• Motivation/Goals• Vault Overview• Discussion• NSF• Status

An Aside on • Vault is written (mostly) in Ruby– Don’t have to use it• Has a command line & web interface

– But…• Not all operations are accessible from command line• You need to write submission/analysis scripts anyway

• Will GEM5 stand for this “ruby” thing?– The simulator side component is in C

• Want it in Python?– I’m available for consultation

So you built a DBMS?(a.k.a. Dear Spyros,)

• Vault does have elements of a DBMS– Serialized commit, file storage, etc.

• But is much more – Interface, Job management, Repository, etc

• Why not use a DBMS under the hood?– I think they are clumsy to work with– Some operations don’t map well (job stats,

permissions)

Outline• Elephants• Motivation/Goals• Vault Overview• Discussion• NSF• Status

Motivation• There is no unified data management plan– Collaborating can be a pain– Interpreting data can be a pain– Unstructured data is error prone

• Custom parsers for every experiment, etc

• Loosely unified job management– Condor, but everyone has their own submission

scripts• Some people (me) need enforced organization– Vault was made for me. Maybe you’ll like it too.

Goals• Repeatability– Don’t do anything until you know you can do it again

• Flexibility– Multiple tools– Storage – Migration & compression– Scheduling

• Promote Collaboration– Share data, actively work together– Protect data with permissions

• Data Integrity

A Note on Storage• Why focus on storage reduction/management?– Aren’t stats just text files?

• Case Study: Rocks– Typical job:

• Stat file: 170K• Stdout: 743• Stderr: 27K• Config: 17K

– Total: 215K/job– 215K * 2000 jobs = 430M of text per experiment!!

• Key: Most of the text is redundant

Outline• Elephants• Motivation/Goals• Vault Overview• Discussion• NSF• Status

What is Vault?

• Demo Time!

Features• Search• Consistency• Repeatability• Flexible permissions• Multiple views• Flexible storage options• Documentation• Result parsing tools• Modular software architecture• Annotations

Configuration

Vault Object OrganizationRepository

ExperimentExperiment

Experiment

Job ScaffoldJob Scaffold

Job ScaffoldJob Scaffold

Job ScaffoldRun

Apparatus

Job ScaffoldJob Scaffold

Job

Stat MiscOut MiscOut

Scheduler

Vault Repositories• Three components:– One Metafile– One or more Storage Directories– One or more Sandbox Directories

• Access managed by filesystem• To share or not to share?– + Increase collaboration– - Hard to manage storage needs– - Limited data protection– Vault’s answer: repository linking

Repository Linking

Derek’s Repository

~drh5/vault.storage Perm: 744

Polina’s Repository

~pdudnik/vault.storage Perm: 744

Calvin Repository

…/projects/calvin/vault.storage Perm: 774

Implementation Note

• Vault uses a flat storage scheme– Every object is a “blob” identified by a hash of its contents

• Benefits– Objects can be stored anywhere

• Repository Linking is easy• Storage management is flexible

– Identical files are stored once• Hash Collision?

– Chance is order 1:2^80. And it’s good enough for git.

~/vault.storage

5CA…1AB 1E0…BAD CAF…EBA BE0…111

Experiments• Complete description of an experiment– Copy of the tool (apparatus)– Copy of all inputs– Copy of commands

• Becomes immutable once run– Exception: annotations

• Key to repeatability

Apparatus• Describes how to control a tool– SCM control– Building– Running

• Allow Vault to be used with many different tools

• Apparati are vault plugins– Ruby code– Saved with the experiment

Scheduler• Controls where and when jobs are run• Like Apparati, are Vault plugins• Two existing (more possible):– SerialScheduler– MultifacetCondorScheduler

Run• Container for a run of an experiment• Experiments may be run multiple times

• Contains:• Scheduler, Jobs

Job Scaffold• Describes how a job is configured & controlled• Elements:– Configuration– Command line– Repetitions

Configuration• Can be:• A standard vault configuration • <key>:<value> list

• A non-standard text file

Stats• All vault tools *must* use the vault stat

infrastructure• C/C++ library– Collection of macros• vs_new_signed_scalar(name, desc, data_ptr)• vs_new_signed_sarray(name, desc, size, array_ptr)• etc.

– Below tool stat managers (e.g., GEM5 stat class)– Includes stat server for real-time updates

Stat File Format• Produces two files– Header• XML description of stats

– Data• Binary data file

• Most jobs from same tool produce identical headers– Vault’s storage stores one copy

• Data files are small

Views• Two (three?) views– Command line– Web server– Access through Ruby

• PIs: only need to know one command– vault serve

• Demo to follow

Configuration

Vault OrganizationRepository

ExperimentExperiment

Experiment

Job ScaffoldJob Scaffold Job Mold

Job ScaffoldJob Scaffold

Run Apparatus

Job ScaffoldJob Scaffold

Job

Stat MiscOut MiscOut

Scheduler

Data Analysis• Unified data storage/access leads to common

analysis tools/techniques• Vault comes with a few neat parsing helpers– e.g., in Ruby:

– Finds all jobs matching config, gets the stat “insns” from each, and returns the arithmetic mean of all of them

insns = repo.find(:config => some_config).insns.arith_mean

Outline• Elephants• Motivation/Goals• Vault Overview• Discussion• NSF• Status

About Repeatability• Vault experiments are repeatable because:– Experiments are run from versioned source code– Inputs are logged

• Vault experiments may not be repeatable if– The SCM repository moves/disappears– Software update• But, can reconstruct the original software

Data Integrity• Vault behaves like an SCM/DBMS– Nothing is written to the repository until commit

• Allows script development without polluting repository

Best Practices• TBD– Storage structure?– Experiment naming convention?– What to do when something goes wrong?

(experiment fails)

Outline• Elephants• Motivation/Goals• Vault Overview• Discussion• NSF• Status

NSF Data Management Plans• the types of data, samples, physical collections,

software, curriculum materials, and other materials to be produced in the course of the project;– Vault stat files

• the standards to be used for data and metadata format and content (where existing standards are absent or deemed inadequate, this should be documented along with any proposed solutions or remedies);– Vault can conform to *any* standard (stat templates)

NSF Data Management Plans• policies for access and sharing including

provisions for appropriate protection of privacy, confidentiality, security, intellectual property, or other rights or requirements;– Filesystem permissions

• policies and provisions for re-use, re-distribution, and the production of derivatives; and– Vault’s emphasis on repeatability

NSF Data Management Plans• plans for archiving data, samples, and other

research products, and for preservation of access to them.– Vault’s emphasis on repeatability– Data is backed up in AFS