2. Installation Guide

2.16. Cluster Installation and Config

2.16.1. Creating New Cluster Setup

Run the Virtuoso 6 Unix ( MacOsX) installer to perform a default installation:

$ tar xvf virtuoso-universal-server-6.1.tar 
x install.sh
x universal-server.taz
$ sh install.sh

- Extracting Virtuoso Universal Server v6.1

- Creating default environment settings

- Creating default database settings
Configuring: database
Creating directory $VIRTUOSO_HOME/database/backup
Installing new virtuoso.ini in $VIRTUOSO_HOME/database
Installing new php.ini in $VIRTUOSO_HOME/database
Creating symlink to $VIRTUOSO_HOME/bin/virtuoso-iodbc-t

- Registering ODBC drivers

- Registering .NET provider for Mono

- Installing VAD packages in database (this can take some time)

- Checking where license should be stored

- Starting OpenLink License Manager

- Checking for initial Virtuoso license

- Starting Virtuoso server instance

- Finalizing installation


This concludes the first part of the installation.


- Attempting to start browser

Please start a browser manually and open the following URL to finalize 
the installation process:

     http://cname:8890/install/


Installation completed
$

Determine how many nodes you want to start the cluster with: 2, 3, 4, 5, 6, 7, 8 etc. Note: the number of the nodes should be >= 2

Setup Virtuoso environment and stop default database:

$ . ./virtuoso-environment.sh
$ virtuoso-stop.sh
Shutting down Virtuoso instance in [database]
$

Optionally remove the default database such that is does not get started with the cluster:
```
rm  -rf database	
```

Full list of supported options for the script "virtuoso-mkcluster.sh":

  -cluster-size       Number of nodes in cluster
  -cluster-node       Node number in a cluster
  -cluster-port       Base portnumer for cluster
  -cluster-ipc-port   Base portnumer for cluster IPC	
  -cluster_size       Size of the cluster
  -virtuoso_home      Virtuoso home path

Run the virtuoso-mkcluster.sh script to create the cluster, note the default number of nodes is 4, but this can be changed by setting the environment variable CLUSTER_SIZE to the required number of nodes to be created before running the script:

$ virtuoso-mkcluster.sh 
Configuring cluster node: 1/4

Creating directory $VIRTUOSO_HOME/cluster_01
Creating directory $VIRTUOSO_HOME/cluster_01/backup
Creating directory $VIRTUOSO_HOME/cluster_01/logs
Installing new virtuoso.ini in $VIRTUOSO_HOME/cluster_01
Installing new php.ini in $VIRTUOSO_HOME/cluster_01
Creating symlink to $VIRTUOSO_HOME/bin/virtuoso-iodbc-t
Configuring cluster node: 2/4

Creating directory $VIRTUOSO_HOME/cluster_02
Creating directory $VIRTUOSO_HOME/cluster_02/backup
Installing new virtuoso.ini in $VIRTUOSO_HOME/cluster_02
Removing unneeded sections from virtuoso.ini
Creating symlink to $VIRTUOSO_HOME/bin/virtuoso-iodbc-t
Configuring cluster node: 3/4

Creating directory $VIRTUOSO_HOME/cluster_03
Creating directory $VIRTUOSO_HOME/cluster_03/backup
Installing new virtuoso.ini in $VIRTUOSO_HOME/cluster_03
Removing unneeded sections from virtuoso.ini
Creating symlink to $VIRTUOSO_HOME/bin/virtuoso-iodbc-t
Configuring cluster node: 4/4

Creating directory $VIRTUOSO_HOME/cluster_04
Creating directory $VIRTUOSO_HOME/cluster_04/backup
Installing new virtuoso.ini in $VIRTUOSO_HOME/cluster_04
Removing unneeded sections from virtuoso.ini
Creating symlink to $VIRTUOSO_HOME/bin/virtuoso-iodbc-t
$

For each of the cluster_XX directories created edit the cluster.ini file and set the HostXX parameter to the hostname:portno to be used by the cluster nodes for internal communication.

$ more cluster_01/cluster.ini
[Cluster]
Threads             = 20
Master              = Host1
ThisHost            = Host1
ReqBatchSize        = 10000
BatchesPerRPC       = 4
BatchBufferBytes    = 20000
LocalOnly           = 2
MaxKeepAlivesMissed = 1000
Host1               = hostname:22201
Host2               = hostname:22202
Host3               = hostname:22203
Host4               = hostname:22204
MaxHosts            = 5
$ more cluster_02/cluster.ini
[Cluster]
Threads             = 20
Master              = Host1
ThisHost            = Host2
ReqBatchSize        = 10000
BatchesPerRPC       = 4
BatchBufferBytes    = 20000
LocalOnly           = 2
MaxKeepAlivesMissed = 1000
Host1               = hostname:22201
Host2               = hostname:22202
Host3               = hostname:22203
Host4               = hostname:22204
MaxHosts            = 5
$ more cluster_03/cluster.ini
[Cluster]
Threads             = 20
Master              = Host1
ThisHost            = Host3
ReqBatchSize        = 10000
BatchesPerRPC       = 4
BatchBufferBytes    = 20000
LocalOnly           = 2
MaxKeepAlivesMissed = 1000
Host1               = hostname:22201
Host2               = hostname:22202
Host3               = hostname:22203
Host4               = hostname:22204
MaxHosts            = 5
$ more cluster_04/cluster.ini
[Cluster]
Threads             = 20
Master              = Host1
ThisHost            = Host4
ReqBatchSize        = 10000
BatchesPerRPC       = 4
BatchBufferBytes    = 20000
LocalOnly           = 2
MaxKeepAlivesMissed = 1000
Host1               = hostname:22201
Host2               = hostname:22202
Host3               = hostname:22203
Host4               = hostname:22204
MaxHosts            = 5
$

Start the cluster using the standard virtuoso-start.sh script which automatically detects the number for nodes to be started:

$ virtuoso-start.sh
Starting Virtuoso instance in [cluster_01]
Starting Virtuoso instance in [cluster_02]
Starting Virtuoso instance in [cluster_03]
Starting Virtuoso instance in [cluster_04]
$

The default SQL port of the master node is 12201, as indicated in the virtuoso.ini file of the cluster_01 directory, and can then be used for connecting to the newly created cluster and check its status to ensure all nodes are online:

$ isql 12201
Connected to OpenLink Virtuoso
Driver: 06.01.3127 OpenLink Virtuoso ODBC Driver
OpenLink Interactive SQL (Virtuoso), version 0.9849b.
Type HELP; for help and EXIT; to exit.
SQL> status ('cluster');
REPORT
VARCHAR
_______________________________________________________________________________

Cluster 4 nodes, 4 s. 1 m/s 0 KB/s  0% cpu 0%  read 0% clw threads 1r 0w 0i buffers 2981 0 d 0 w 0 pfs

1 Rows. -- 7 msec.
SQL> cl_ping(1,500, 1000);

Done. -- 7 msec.
SQL> cl_ping(2,500, 1000);

Done. -- 52 msec.
SQL> cl_ping(3,500, 1000);

Done. -- 60 msec.
SQL> cl_ping(4,500, 1000);

Done. -- 51 msec.
SQL>

To split the node across across physical machines for better performance and scalability, simply perform a parallel Virtuoso installation on the additional physical machines and move the cluster nodes required to the designated machine. Example, for the default 4 node cluster to be split across two identical machines it would make sense to split 2 nodes across each machine, thus you would move say the cluster_03 and cluster_04 directory nodes to the new machine (removing them from the original). The cluster.ini file on each node would then need to be updated to set the HostXX parameters to point to the new locations for nodes 03 and 04:

Machine 1 (hostname1)

$ more cluster_01/cluster.ini
[Cluster]
Threads             = 20
Master              = Host1
ThisHost            = Host1
ReqBatchSize        = 10000
BatchesPerRPC       = 4
BatchBufferBytes    = 20000
LocalOnly           = 2
MaxKeepAlivesMissed = 1000
Host1               = hostname1:22201
Host2               = hostname1:22202
Host3               = hostname2:22203
Host4               = hostname2:22204
MaxHosts            = 5
$ more cluster_02/cluster.ini
[Cluster]
Threads             = 20
Master              = Host1
ThisHost            = Host2
ReqBatchSize        = 10000
BatchesPerRPC       = 4
BatchBufferBytes    = 20000
LocalOnly           = 2
MaxKeepAlivesMissed = 1000
Host1               = hostname1:22201
Host2               = hostname1:22202
Host3               = hostname2:22203
Host4               = hostname2:22204
MaxHosts            = 5
$

Machine 2 (hostname2)

$ more cluster_03/cluster.ini
[Cluster]
Threads             = 20
Master              = Host1
ThisHost            = Host3
ReqBatchSize        = 10000
BatchesPerRPC       = 4
BatchBufferBytes    = 20000
LocalOnly           = 2
MaxKeepAlivesMissed = 1000
Host1               = hostname1:22201
Host2               = hostname1:22202
Host3               = hostname2:22203
Host4               = hostname2:22204
MaxHosts            = 5
$ more cluster_04/cluster.ini
[Cluster]
Threads             = 20
Master              = Host1
ThisHost            = Host4
ReqBatchSize        = 10000
BatchesPerRPC       = 4
BatchBufferBytes    = 20000
LocalOnly           = 2
MaxKeepAlivesMissed = 1000
Host1               = hostname1:22201
Host2               = hostname1:22202
Host3               = hostname2:22203
Host4               = hostname2:22204
MaxHosts            = 5
$

The nodes can then be started on each machine, with 2 nodes being started on each in this case to form the cluster:


Machine 1 (hostname1)

$ virtuoso-start.sh
Starting Virtuoso instance in [cluster_01]
Starting Virtuoso instance in [cluster_02]
$

Machine 2 (hostname2)

$ virtuoso-start.sh
Starting Virtuoso instance in [cluster_03]
Starting Virtuoso instance in [cluster_04]
$

To stop the cluster use the standard virtuoso-stop.sh script which automatically detects the number for nodes to be stopped:

$ virtuoso-stop.sh
Stopping Virtuoso instance in [cluster_01]
Stopping Virtuoso instance in [cluster_02]
Stopping Virtuoso instance in [cluster_03]
Stopping Virtuoso instance in [cluster_04]
$

2.16.2. Backup and Restore

Backup

There are 2 ways to backup Virtuoso Cluster DB:

Backup every node using back_online
For example, for every cluster in its backup folder execute:
```
backup_online ('dbp', 10000000, 0, 'backup');
```

Make backup of all nodes at once using cl_exec. For example, execute:

cl_exec ('backup_online (''dbp'', 10000000, 0,  vector (''backup''))');

Restore from Backup

After backup is done for every node in its backup folder, in order to restore, execute from the ..\bin folder the virtuoso-restore.sh:

# . ./virtuoso-restore.sh all dbp

where the second parameter is the restore prefix.

2.16.3. Cluster Configuration

Set "FAST_START=1" in the viruoso-start.sh file and then run:
```
viruoso-start.sh
```
or

Execute the following line:

# /etc/init.d/virtuoso start
Starting OpenLink Virtuoso:                                [  OK  ]

In order to check the nodes, connect to port 12201 using the ISQL tool:
```
isql 12201
```

To check the cluster status, execute the following command:

SQL> status('cluster');
REPORT
VARCHAR
_______________________________________________________________________________

Cluster 4 nodes, 293 s. 0 m/s 0 KB/s  0% cpu 0%  read 0% clw threads 1r 0w 0i buffers 1781 0 d 0 w 0 pfs

1 Rows. -- 4 msec.

2.16.4. Troubleshooting Tips

If an operation seems to hang, see the output of:

status ()

Check for the presence of the following conditions:

The cluster line shows 0% CPU, no message traffic and an unchanging number of buffers wired, this is probably a bug. To reset, restart the cluster or the offending process if found. Restart is done by executing:
```
raw_exit (); 	
```
over an SQL connection to the process in question.
The cluster line shows many threads waiting compared to total threads. If CPU is 0 and this does not change there could be a transaction that holds locks indefinitely. To clear, execute:
```
txn_killall (1);	
```
Do this at a node that has local threads waiting. This is seen in the Lock Status paragraph of status ('') when connected to the node in question.
The cluster line shows a changing number in the pfs field. The system is swapping and slowed down.
If the status () itself hangs, try another process of the cluster. See that there is no temporary atomic activity like a long checkpoint. If the situation persists there is a bug. The checkpoint can be seen by the presence of the checkpinmt_in_progress file in each server's working directory.
To check the integrity of database files, do:
```
cl_exec ('backup ''/dev/null''');
```
If this returns, the databases are OK. If one is found to be corrupt the corresponding server exits.