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CRX 1.4
TarPersistenceManager and Clustering
with TarPersistenceManager
Speaker: Honwai Wong, SSE
Duration: 45 min
Feedback: techsummit@day.com
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Agenda
 TarPM (TarPersistenceManager)
 Functionality
 Configuration
 Optimization
 Hot Backup
 Migration
 TarPM (TarPersistenceManager) Clustering
 Architecture
 Global Data Store
 Setup
 Configuration
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TarPM
Functionality
 Disk-based PersistenceManager
 Uses standard Tar file format (POSIX standard)
 Append-only write operations, thus extremely efficient
 Particularly suitable for high data creation and modification
use-cases
 Takes advantage of key-value pair data structure of CRX
 Maintains index files for fast access
 Hot backup capability
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TarPM
Configuration
 TarPM configuration is done on a per workspace-level
e.g. <crx_home>/workspaces/crx.default/workspace.xml
 no mandatory parameters, preset with default values
<PersistenceManager class=
quot;com.day.crx.persistence.tar.TarPersistenceManagerquot; />
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TarPM
Configuration - Parameters
Parameter Description default
The directory where local files are stored. This can be an base directory
localPath absolute or relative path. of workspace
If the current data file grows larger than this number (in MB),
maxFileSize 64
a new data file is created.
After an abnormal termination, at most this much data (in
maxIndexBuffer 32
MB) needs to be scanned to re-create the tar entry index.
optimizeSleep Number in milliseconds to wait after each optimization step. 1
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TarPM
Optimization
 Append-only operation leads to increased disk usage
 Data in the tar files is never overwritten
 Delete will append 0 length entries
 Optimization task copies active data from old tar files into new
ones and subsequently deletes old tar files
 Different modes of operation supported
 Recommended to run during times of low system usage
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TarPM
Optimization - Modes
 Manually trigger optimization from CRX Explorer
 Place a file called optimize.tar in data-directory
 TarPM detects this file and starts optimization
 optimize.tar is renamed to optimizeNow.tar
 after optimization finished, optimizeNow.tar is deleted automatically
 stop task by deleting this file
 Automate using cron-job
 Offline optimization using command-line tool
 java -cp <jars> com.day.crx.persistence.tar.TarUtils -optimize <directory>
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TarPM
Hot Backup
 Reminder: tar files are append-only
 Backup at any time including runtime
 Place file stopdelete.tar to prevent the TarPM from deleting old
files while backing up
 Consistent backup by copying data_*.tar files, sorted by
modification date, newest last
 e.g. ls -tr data_*.tar | xargs -n1 -J % cp -v % /backup
 When restoring, incomplete transactions are rolled back
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TarPM
Migration
 Migration of workspaces using CRX Console
 Low-level copy of existing workspace to new TarPM workspace
 Tool is provided with CRX
 Comprehensive documentation on docs.day.com
 see section CQ 4.2 / Setup / Migration
 Part of migration presentation from Tech Summit 2007
 http://daycare.day.com/home/day_public/tech_summit_2007.html
 Author: Dominique Jaeggi, SSE, Day
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TarPM Clustering
Architecture
 Master/Slave relation between CRX cluster nodes participating
in a cluster
 Consists of 2 or more CRX cluster nodes with TarPM
 Synchronization via file-based Cluster Journal
 Direct communication between cluster nodes via TCP/IP using
HTTP
 Only Master CRX node writes data
 Master is elected automatically
 Automatic fail-over
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TarPM Clustering
Architecture - Overview
Cluster Node A Cluster Node B
(Master)
s
old
H s CRX CRX
ock Journal posts
L to master
TAR PM TAR PM
master write
read
master write
read
Master Data TAR
Cluster
Journal (FS)
FS
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TarPM Clustering
Global Data Store
 Central storage for binary data, even beyond repository
boundaries
 Only one copy per unique object is kept
 Storing and reading does not block other users, done outside
Persistence Manager
 Objects in the Data Store are immutable
 Only unique data identifier of existing objects in the Data Store
are stored in the Persistence Manager
 Transactional semantics guaranteed
 Hot Backup by simply copying all files :)
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TarPM Clustering
Global Data Store - Configuration
 Configured in repository.xml of CRX
 e.g. <crx_home>/server/runtime/0/_crx/WEB-INF/repository.xml
 File-based or database-backed
 org.apache.jackrabbit.core.data.FileDataStore
 org.apache.jackrabbit.core.data.db.DbDataStore
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TarPM Clustering
FileDataStore - Config Parameters
Parameter Description default
repository.home/
path The directory where to store binary objects. repository/datastore
Binary objects bigger than this value (in bytes) are
minRecordLength 100
stored in the Data Store.
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TarPM Clustering
DbDataStore - Config Parameters
Parameter Description default
url The database URL used to access the database. -
user Name of the database-user. -
password Password of the user. -
Binary objects bigger than this value (in bytes) are
minRecordLength 100
stored in the Data Store.
maxConnections The maximum number of open connections. 3
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TarPM Clustering
Architecture
Cluster Node A Cluster Node B
(Master)
s
old
H s
ock
CRX CRX
L Journal posts
to master
TAR PM TAR PM
master write
read
master write
read
Master Data TAR
Cluster
Journal (FS)
Global Data Store
FS
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TarPM Clustering
Setup
 Install CRX
 Configure clustering in repository.xml
 Configure TarPM to run in cluster mode
 Setup additional CRX cluster node by copying complete
instance
 Delete repository-local revision, if present
 On startup, CRX cluster node will sync up with master data
based on journal
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TarPM Clustering
Repository Configuration
 Enable clustering on a repository-wide level
 e.g. <crx_home>/runtime/0/_crx/WEB-INF/repository.xml
 Unique cluster id
 Cluster Journal
<Cluster id=quot;cluster-node-1quot; syncDelay=quot;1quot;>
<Journal class=quot;org.apache.jackrabbit.core.journal.FileJournalquot;>
<param name=quot;revisionquot; value=quot;${rep.home}/revision.logquot; />
<param name=quot;directoryquot; value=quot;/data/shared/journalquot; />
</Journal>
</Cluster>
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TarPM Clustering
Repository Configuration - Parameters
luster
C
Parameter Description
id This is required to be a unique literal id of the cluster node.
Delay in milliseconds before changes to the journal are
syncDelay automatically detected. Default: 5000
urnal
Jo
Parameter Description
FQN of org.apache.jackrabbit.core.journal.Journal interface
class
implementation.
revision Location and filename of repository-local revision counter.
directory Shared directory of journal entries and global revision counter.
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TarPM Clustering
Workspace Configuration
 enable clustering on the TarPM
 e.g. <crx_home>/crx/workspaces/crx.default/workspace.xml
 set cluster flag
 configure local and shared paths
<PersistenceManager class=quot;com.day.crx.persistence.tar.TarPersistenceManagerquot;>
<param name=quot;clusterquot; value=quot;truequot; />
<param name=quot;localPathquot; value=quot;${wsp.home}quot; />
<param name=quot;sharedPathquot; value=quot;/data/sharedquot; />
</PersistenceManager>
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TarPM Clustering
TarPM Configuration - Parameters
Parameter Description default
cluster Enables clustering. FALSE
localPath Path where to store local tar-files and index-files. workspace.home
sharedPath Path where to store shared data, i.e. tar-files. workspace.home
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TarPM
Questions?
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