Severalnines Self-Training: MySQL® Cluster - Part VII

Severalnines Self-Training: MySQL® Cluster - Part VII

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  MySQL Cluster Training presented by severalnines.com Address: Contact: SeveralninesAB Jean-Jérôme Schmidt c/o SICS, Box 1263 Email: [email protected] Isafjordsgatan22 SE-164-29 Kista Copyright 2011 Severalnines AB Control your database infrastructure 1
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  Introduction • At Severalnines, we believe in sharing information and knowledge; we all come from an open source background • We know a lot of things about MySQL Cluster and think that MySQL Cluster is a great technology • These free MySQL Cluster Training slides are a contribution of ours to the knowledge and information sharing that‟s common practice in the open source community • If you have any questions on these slides or would like to book an actual training class, please contact us at: [email protected] Copyright 2011 Severalnines AB Control your database infrastructure 2
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  Training Slides -Concept • Over the coming weeks we will be chronologically releasing slides for the different sections of our MySQL Cluster Training program on our website. • The full agenda of the training with all of its modules is outlined in the next slides so that you can see what topics will be covered over the coming weeks. • Particularly specialised topics such as Cluster/J or NDB API are not fully covered in the slides. We recommend our instructor-led training classes for such topics. • Please contact us for more details: [email protected] Copyright 2011 Severalnines AB Control your database infrastructure 3
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  Full Training Agenda(1/4) • MySQL Cluster Introduction – MySQL eco system – Scale up, scale out, and sharding – MySQL Cluster Architecture – Use cases – Features – Node types and Roles • Detailed Concepts – Data Distribution – Verifying data distribution – Access Methods – Partitioning – Node failures and failure detection – Network Partitioning – Transactions and Locking – Consistency Model – Redo logging and Checkpointing • Internals – NDB Design Internals Copyright 2011 Severalnines AB Control your database infrastructure 4
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  Agenda (2/4) • Installing MySQL Cluster – Setting up MySQL Cluster – Starting/stopping nodes – Recovery and restarts – Upgrading configuration – Upgrading Cluster • Performance Tuning (instructor-led only; contact us at [email protected]) – Differences compared to Innodb/MyISAM – Designing efficient and fast applications – Identifying bottlenecks – Tweaking configuration (OS and MySQL Cluster) – Query Tuning – Schema Design – Index Tuning Copyright 2011 Severalnines AB Control your database infrastructure 5
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  Agenda (3/4) • Management and Administration – Backup and Restore – Geographical Replication – Online and offline operations – Ndbinfo tables – Reporting – Single user mode – Scaling Cluster • Disk Data – Use cases – Limitations – Best practice configuration • Designing a Cluster – Capacity Planning and Dimensioning – Hardware recommendations – Best practice Configuration – Storage calculations Copyright 2011 Severalnines AB Control your database infrastructure 6
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  Agenda (4/4) • Resolving Issues – Common problems – Error logs and Tracefiles – Recovery and Escalation procedures • Connectivity Overview – NDBAPI – Cluster/J – LDAP • Severalnines Tools – Monitoring and Management – Benchmarking – Sandboxes – Configuration and capacity planning • Conclusion Copyright 2011 Severalnines AB Control your database infrastructure 7
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  Agenda: Lab Exercises (only applicable to instructor-led training classes) • Lab Exercises – Installing and Loading data into MySQL Cluster – Starting/stopping nodes, recovery – Query tuning – Backup and Restore – Configuration Upgrade • Would you like to try something particular? – This is possible too, speak with your instructor Copyright 2011 Severalnines AB Control your database infrastructure 8
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  Prerequisites • Readers / Participants have understanding of SQL and basic database concepts. • Laptops/PCs for hands-on exercises • Linux: 1GB RAM • Windows: 2GB RAM • Approx. 20GB disk space and Virtualbox installed. • Virtualbox can be downloaded for free at http://www.virtualbox.org/wiki/Downloads • MySQL Cluster version 7.1 or later Copyright 2011 Severalnines AB Control your database infrastructure 9
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  7th Installment Severalnines Cluster Self-Training Part 6: Management and Administration Copyright 2011 Severalnines AB Control your database infrastructure 10
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  Topics covered inInstallment 7 • Backup and Restore • Geographical Redundancy • Online and offline operations • Ndbinfo tables • Reporting • Single user mode • Scaling Cluster Copyright 2011 Severalnines AB Control your database infrastructure 11
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  Management and Administration Backup and Restore Copyright 2011 Severalnines AB Control your database infrastructure 12
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  Backup and Restore • The following should be backed up in MySQL Cluster – NDBCLUSTER tables – MySQL System tables (stored in MYISAM) – MYISAM/INNODB tables – optional – Binary logs (optional) – Configuration files (config.ini and my.cnf) Copyright 2011 Severalnines AB Control your database infrastructure 13
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  Backup and Restore • NDBCLUSTER tables – ONLINE BACKUP is built into MySQL Cluster • Only tables stored in the NDBCLUSTER storage engine can be backed up ONLINE. • INNOB/MYISAM tables – mysqldump – Oracle Hotbackup • Binary logs – Copy/rsync • Config files – Copy/rsync Copyright 2011 Severalnines AB Control your database infrastructure 14
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  Online Backup START BACKUP • Backups are started from the management client or mgmapi – ndb_mgm –e “START BACKUP” Management server • Each data node will backup its STORAGE LAYER primary partition – Consistent at “backup complete” DATA DATA “backup start” time, as you wish NODE 1 NODE 2 • Thus the complete backup is P0 P1 spread over several computers S1 S0 Copyright 2011 Severalnines AB Control your database infrastructure 15
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  Online Backup START BACKUP • Backups are written to a backup directory: Management server – Default : DATADIR – BACKUP_DATADIR STORAGE LAYER • BACKUP_DATADIR can be a mount point on a SAN. DATA NODE 1 DATA NODE 2 • Each backup gets an ID – Starting from 1 and always incrementing P0 P1 S1 S0 • The backup consists of three files: – Data file (the records in data memory) • Backup-1.data – Log file (changes during the backup) • Backup-1.log – Meta data (indexes and tables) /data/mysqlcluster/BACKUP/BACKUP-1 • Backup-1.ctl Copyright 2011 Severalnines AB Control your database infrastructure 16
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  Backup and Restore • Exercise – BACKUP Copyright 2011 Severalnines AB Control your database infrastructure 17
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  Restore • The ndb_restoreprogram is used to a MySQL Cluster backup. • A backup taken from two data nodes will have two sets of backup files – A backup taken from four data nodes will have four sets of backup files. • All backup sets must be restored – Ndb_restore can restore one backup set at a time. – Exception – meta data needs to be restored only once. Copyright 2011 Severalnines AB Control your database infrastructure 18
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  Restore • Two data nodes with id=2 and id=3, backup id=1 • To restore the meta data (needs to be executed only once): ndb_restore –c<connectstring> --restore_meta --node-id=2 --backup-id=1 /path/to/backup/files • To restore the data and logs – must be executed once for each backup set: ndb_restore –c<connectstring> --restore_data --node-id=2 --backup-id=1 /path/to/backup/files ndb_restore –c<connectstring> --restore_data --node-id=3 --backup-id=1 /path/to/backup/files Copyright 2011 Severalnines AB Control your database infrastructure 19
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  Backup and Restore • Exercise – Restore Copyright 2011 Severalnines AB Control your database infrastructure 20
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  Backup and Restore • SeveralninesClusterControl allows you to: – Backup data to a central location instead of having the backup files spread out of X computers. – Create backup schedules – Check backup history – Restore backups easily Copyright 2011 Severalnines AB Control your database infrastructure 21
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  Geographical Redundancy • Uses the Normal MySQL Replication to transfer data between a Master and a Slave. – Binary logs – Positions as offsets in the files. • Added extra information to allow failover. Copyright 2011 Severalnines AB Control your database infrastructure 22
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  Geographical Redundancy STORAGE LAYER • Application inserts data • Committed changes from DATA DATA NODE 1 NODE 2 data nodes are sent to all mysql servers with --log- P0 P1 bin set. S1 S0 – This means that several mysql servers can have MASTER – serverid=1 equivalent binary log Injector Thead BINARY LOG Copyright 2011 Severalnines AB Control your database infrastructure 23
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  Geographical Redundancy STORAGE LAYER DATA DATA NODE 1 NODE 2 P0 P1 S1 S0 MASTER – serverid=1 BINARY LOG Copyright 2011 Severalnines AB Control your database infrastructure 24
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  Geographical Redundancy STORAGE LAYER DATA DATA NODE 1 NODE 2 P0 P1 S1 S0 MASTER – serverid=1 BINARY LOG Copyright 2011 Severalnines AB Control your database infrastructure 25
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  Geographical Redundancy STORAGE LAYER • Every TimeBetweenEpochs DATA NODE 1 DATA NODE 2 (default 100ms) there is a EPOCH_COMPLETE P0 P1 message sent to the S1 S0 Masters. EPOCH_COMPLETE 12 • The Master binlog buffer MASTER – serverid=1 will be flushed to the Binary log • Epochs contains 0 or BINARY LOG more transactions Copyright 2011 Severalnines AB Control your database infrastructure 26
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  Geographical Redundancy NDB_BINLOG_INDEX STORAGE LAYER Epoch Binlog Pos Type DATA DATA 12 b.01 4 I NODE 1 NODE 2 12 b.01 28 I P0 P1 12 b.01 32 U S1 S0 15 b.01 255 U • The NDB_BINLOG_INDEX is updated. • Stores a map between Epoch Copy to Binary log and Binlog/pos 12 4 28 32 255 Copyright 2011 Severalnines AB Control your database infrastructure 27
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  Geographical Redundancy NDB_APPLY_STATUS STORAGE LAYER Epoch Binlog Pos Type DATA DATA 12 b.01 4 I NODE 1 NODE 2 12 b.01 28 I P0 P1 12 b.01 32 U S1 S0 15 b.01 255 U • The Master writes the unsent MASTER binary log data to the slave network 12 4 28 32 255 Copyright 2011 Severalnines AB Control your database infrastructure 28
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  Geographical Redundancy STORAGE LAYER STORAGE LAYER DATA DATA DATA DATA NODE 1 NODE 2 NODE 1 NODE 2 P0 P1 P0 P1 S1 S0 S1 S0 MASTER – serverid=1 SLAVE IO THREAD receives data and put in RELAY LOG Copy to Binary log 12 12 4 28 32 255 4 28 32 255 Copyright 2011 Severalnines AB Control your database infrastructure 29
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  Geographical Redundancy STORAGE LAYER DATA DATA NODE 1 NODE 2 P0 P1 S1 S0 SLAVE SQL Thread reads from the RELAY LOG 12 4 28 32 255 Copyright 2011 Severalnines AB Control your database infrastructure 30
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  Geographical Redundancy STORAGE LAYER DATA DATA NDB_APPLY_STATUS NODE 1 NODE 2 Server Id Last Epoch P0 P1 1 12 S1 S0 • NDB_APPLY_STATUS SLAVE • Last applied epoch and Applies the entire epoch and updates NDB_APPLY_STATUS table where it came from. 12 • An epoch is applied as 4 28 32 255 one transaction. Copyright 2011 Severalnines AB Control your database infrastructure 31
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  Geographical Redundancy Failover Ndb_ MASTER – serverid=1 SLAVE Binlog ndex Copy to Binary log IO THREAD receives data and put in RELAY LOG 12 12 4 28 32 255 4 28 32 255 STORAGE LAYER STORAGE LAYER DATA DATA DATA DATA NODE 1 NODE 2 NODE 1 NODE 2 NDB_APPLY_STATUS P0 P1 P0 P1 S1 S0 S1 S0 MASTER – serverid=2 SLAVE Ndb_ Binlog ndex Copy to Binary log 12 4 28 32 255 4 28 32 255 Copyright 2011 Severalnines AB Control your database infrastructure 32
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  Geographical Redundancy Failover Ndb_ MASTER – serverid=1 SLAVE Binlog ndex Copy to Binary log 14 12 4 28 32 255 4 28 32 255 STORAGE LAYER STORAGE LAYER DATA DATA DATA DATA NODE 1 NODE 2 NODE 1 NODE 2 NDB_APPLY_STATUS 1 - 12 P0 P1 P0 P1 S1 S0 S1 S0 MASTER – serverid=2 SLAVE Ndb_ Binlog Failover –check what is the applied epoch. ndex Find corresponding binlog/pos. Copy to Binary log Change master Start replication 14 4 28 32 255 4 28 32 255 Copyright 2011 Severalnines AB Control your database infrastructure 33
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  Staging the slave • The slave cluster is staged by restoring a backup from the Master Cluster – ndb_restore … -e • -e - restore epoch • The –e is very important, otherwise the slave cluster will not get the last applied epoch written in ndb_apply_status table. • The last applied epoch will be the epoch when the backup finished. Copyright 2011 Severalnines AB Control your database infrastructure 34
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  Geographical Redundancy • It is also possible to have conflict detection and resolution. • Out of scope in this training. Copyright 2011 Severalnines AB Control your database infrastructure 35
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  Geographical Redundancy • Exercise – setup Geo rep. Copyright 2011 Severalnines AB Control your database infrastructure 36
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  Management and Administration Offline and online operations Copyright 2011 Severalnines AB Control your database infrastructure 37
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  Online/offline Operations • Online Operation – There can still be traffic on the Cluster while the operation is taking place – No Service Interruption • Offline Operation – Traffic needs to be blocked in order to implement the change. – Service Interruption Copyright 2011 Severalnines AB Control your database infrastructure 38
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  Online operations • Adding nodes – Adding data nodes – Adding mysql servers • Changing configuration – values except • Hostnames • NoOfReplicas • Upgrade – Software – Hardware – OS • Schema modifications – Add column (ALTER ONLINE TABLE… ADD COLUMN x INT) – Create Index / Drop Index Copyright 2011 Severalnines AB Control your database infrastructure 39
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  Offline operations • NoOfReplicas=2  3 – Requires a backup and restore • Schema Changes – data types, column sizes, names – The table in question must be locked: • On all mysql servers except one: LOCK TABLE t1 READ; • On the exception: ALTER TABLE t1 MODIFY b CHAR(255); • UNLOCK TABLES; Copyright 2011 Severalnines AB Control your database infrastructure 40
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  Management and Administration Monitoring Copyright 2011 Severalnines AB Control your database infrastructure 41
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  Monitoring MySQL Cluster • MySQL Cluster offers the following monitoring interfaces – NDBINFO - containing system tables stored accessible from the mysql server – LOGEVENTs – subscribe using the mgmapi • SeveralninesClusterControl collects information from both these sources. – Web interface – Command line tools Copyright 2011 Severalnines AB Control your database infrastructure 42
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  NDBINFO • The NDBINFO (MySQL Cluster 7.1 and later) is a schema containing statistical counters collected from the data nodes. – Memory usage (memoryusage) – Statistical counters (counters) – Redo log information (logspaces) – Redo buffer information (logbuffers) – Disk page buffer memory stats (diskpagebuffer) • All this information is also collected by SeveralninesClusterControl. Copyright 2011 Severalnines AB Control your database infrastructure 43
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  How do youspot issues? • ClusterControl can assist – Query Monitoring/Histogram – Health Reports – Configuration Management • You can also watch our video describing how to find configuration issues: http://www.severalnines.com/resources/videos Copyright 2011 Severalnines AB Control your database infrastructure 44
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  How do youspot issues? Copyright 2011 Severalnines AB Control your database infrastructure 45
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  How do youspot issues? Copyright 2011 Severalnines AB Control your database infrastructure 46
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  How do youspot issues? Copyright 2011 Severalnines AB Control your database infrastructure 47
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  Management and Administration Reporting Copyright 2011 Severalnines AB Control your database infrastructure 48
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  Reporting • Best practice is to separate reporting from the real- time database. – Running reporting on a realtime database will affect performance. • From MySQL Cluster it is possible to replicate to an InnodbMySQL server. – Run the reporting/heavy queries on this server. Copyright 2011 Severalnines AB Control your database infrastructure 49
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  Reporting MySQL Cluster Application/realtime Reporting, heavy queries DATA Sync repl. DATA NODE 0 NODE 1 Asynch. replication Replication servers Copyright 2011 Severalnines AB Control your database infrastructure 50
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  Reporting • How to set it up – http://johanandersson.blogspot.com/2009/05/ha-mysql-write- scaling-using-cluster-to.html • If one master fails, the reporting slave can failover to the other master – No data loss • If the reporting slave fails – restart it – The reporting slave can reconnect and resume. Copyright 2011 Severalnines AB Control your database infrastructure 51
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  Management and Administration Single User Mode Copyright 2011 Severalnines AB Control your database infrastructure 52
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  Single User Mode • MySQL Cluster has a Single User Mode that it is possible to enter. In practice it is rarely used. • ndb_mgm> ENTER SINGLE USER MODE 7 – This means that only an application with Nodeid=7 is allowed to connect and operate on MySQL Cluster – All other applications will be blocked • ndb_mgm> EXIT SINGLE USER MODE – Only useful if you have a dedicated adminstrative MySQL Server. – Then you “lock” the database and you can do offline ALTER TABLEs from this MySQL Server. Copyright 2011 Severalnines AB Control your database infrastructure 53
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  Management and Administration Scaling MySQL Cluster Copyright 2011 Severalnines AB Control your database infrastructure 54
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  Scaling MySQL Cluster • MySQL Cluster consists of two layers that can be scaled – Data/storage Layer – Access Layer (mysql servers, application nodes) • But how to know when it is time to scale? • The following variables need to be studied – Network • Iftop – Disk • Iostat – CPU • top • vmstat Copyright 2011 Severalnines AB Control your database infrastructure 55
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  SQL Layer/Access Layer • To determine if the SQL Layer / Access Layer needs to be scaled, it is sufficient to look at the CPU utilization. (Network saturation is not very common). – However if CPU utlization is low AND cpu utilization is low on the data nodes the requests are spending time in the network. • Optimize those request (better indexes, force index etc) • MySQL Servers can be added online, just install the binaries, issue GRANTs and start the MySQL Server. – Make sure you have connection slots available. • With SeveralninesClusterControl, a new MySQL Server can be provisioned with a single click. Copyright 2011 Severalnines AB Control your database infrastructure 56
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  Data Layer /Storage Layer • Network – Is the network fully utilized (this is very very seldom the case)? • CPU – What is the %util of the TC, LQH or CMVMI threads? – cat /data/mysqlcluster/ndb_X_out.log |greptid • The PIDs of the different threads are printed out – top –Hd1 • Is one of the threads mentioned above running at 100% • If yes  add data node (one node group needs to be added at a time). Copyright 2011 Severalnines AB Control your database infrastructure 57
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  Data Layer /Storage Layer • Disk – iostat –kx 1 – Is the ioutil at 100%? • If yes  by better disks, checkpoint with a lower rate, increase redo log size, • It is also possible to add more data nodes in order to spread out the write load across more instances. • Check if the write back cache is enabled, if not, enable it. – Note – E.g EC2 disks are inherently slow. DiskCheckpointSpeed should be set lower, e.g 5MB/s. Copyright 2011 Severalnines AB Control your database infrastructure 58
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  Add Data NodeOnline • There are two way of adding data nodes – Dynamically / “Hard” - edit config.ini • Cons: You must perform a rolling restart – Statically / “Easy”: Plan ahead and allocate “slots” for data nodes at configuration time • Cons: You must know the hostnames from the beginning. • Pros: Easy • Start with 2 data nodes but configure for 8 data nodes • It is not possible to shrink the number of data nodes. Copyright 2011 Severalnines AB Control your database infrastructure 59
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  Dynamic - AddData Node Online • Edit config.ini and add: [NDBD] Nodeid:X Hostname=„newhost1‟ [NDBD] Nodeid:Y Hostname=„newhost2‟ • Perform a rolling restart in the following order: – Restart the management servers – Restart the mysql servers – Restart the already existing data nodes – Start the data nodes on „newhost1‟ and „newhost2‟ ndbmtd --initial Copyright 2011 Severalnines AB Control your database infrastructure 60
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  “Static/plan ahead”- AddData Node Online • In config.ini before you start Cluster the first time [NDBD] Nodeid:X Nodegroup: 65536 (magic number) Hostname=„newhost1‟ [NDBD] Nodeid:Y Nodegroup: 65536 (magic number) Hostname=„newhost2‟ • To add data nodes simply start the data nodes on „newhost1‟ and „newhost2‟ – ndbmtd –initial • Note, in some releases the magic number is 65535. Copyright 2011 Severalnines AB Control your database infrastructure 61
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  Add Data NodeOnline • In any case the final step is to redistribute the data. • Foreach table do: – ALTER TABLE t1 REORGANIZE PARTITION • This will rehash the table • This is an ONLINE operation. • It will take some time. – http://johanandersson.blogspot.com/2009/03/online-add- node-preliminary-numbers.html – http://johanandersson.blogspot.com/2009/03/online-add- node-preliminary-numbers-2.html • However, it is not a common task to add data nodes. Increasing/decreasing # mysql servers is more common. Copyright 2011 Severalnines AB Control your database infrastructure 62
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  Coming next inInstallment 8: Disk Data Copyright 2011 Severalnines AB Control your database infrastructure 63
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  We hope thesetraining slides are useful to you! Please visit our website to view the next section of this training. For any questions, comments, feedback or to book a training class, please contact us at: [email protected] Thank you! Copyright 2011 Severalnines AB Control your database infrastructure 64
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  Disclaimer © Copyright2011 Severalnines AB. All rights reserved. Severalnines& the Severalnineslogo(s) are trademarks of Severalnines AB. MySQL is a registered trademark of Oracle and/or its affiliates. Other names may be trademarks of their respective owners. Copyright 2011 Severalnines AB Control your database infrastructure 65