1. Reference
  2. TimesTen Scaleout Utilities
  3. ttGridAdmin
  4. Host Operations

Host Operations

Use ttGridAdmin commands in this section to define a host in the model, modify a host, delete a host, run commands on all hosts, or list all hosts.

Create a Host (hostCreate)

The hostCreate command defines a host in the model. 

ttGridAdmin hostCreate [name]
                       [-address addr]
                       [-internalAddress addr]
                       [-externalAddress addr]
                       [-dataspacegroup n]
                       [-nodataspacegroup]
                       [-like name [-cascade]]
                       [-comment comment]

Options

The hostCreate command has the options:

Option Description

name

Specifies the name for the host object in the model. The default is the first component of the operating system host name (the host name up to but not including the first ".", such as myhost).

If this option is omitted, the host system must be accessible through passwordless SSH at the time hostCreate is performed.

-internalAddress addr

DNS name or IP address of the host for internal communications, inside the grid. Use this together with -externalAddress. The host must be accessible by passwordless SSH at the specified address.

This option takes one name or address only, and a specified name must resolve to one IP address or to multiple IP addresses on the same network segment.

If host names from /etc/hosts are being used, the /etc/hosts files on all instances in the grid must contain identical entries for all hosts in the grid.

Also see Notes below and Address Formats.

-externalAddress addr

DNS name or IP address of the host for external communications, outside the grid, for client/server connections. Use this together with -internalAddress. The host must be accessible by passwordless SSH at the specified address.

This option takes one name or address only, but a name may resolve to one or more IP addresses.

If host names from /etc/hosts are being used, the /etc/hosts files on all instances in the grid must contain identical entries for all hosts in the grid.

Also see Notes below and Address Formats.

-address addr

DNS name or IP address of the host for both external and internal communications, if a single address is used. The host must be accessible by passwordless SSH at the specified address.

This option takes one name or address only, and a specified name must resolve to one IP address or to multiple IP addresses on the same network segment.

If host names from /etc/hosts are being used, the /etc/hosts files on all instances in the grid must contain identical entries for all hosts in the grid.

Note: Using a single address is not recommended for production environments.

Also see Notes below and Address Formats.

-dataspacegroup n

Specifies that this host will belong to data space group number n. The number of data space groups a grid has is determined by the k value set for the grid.

A host with a data instance must belong to a data space group.

Also see -nodataspacegroup and Notes below.

Note: Once a host is assigned to a data space group and modelApply is performed, you cannot change the assignment.

-nodataspacegroup

Specifies that the host will not be assigned to a data space group. This is the default.

A host with a data instance must belong to a data space group.

Also see -dataspacegroup and Notes below.

-like name

Specifies that this new host should be created with the same attributes as the named existing host, except where other options that you specify override settings from the existing host.

Also see -cascade.

-cascade

Use this option with the -like option to specify that installations and instances associated with the -like host also be defined for the host being created. (These objects will be defined for the new host, but not actually created until you run modelApply.)

-comment comment

Associates a comment with the host object. Put the comment in quotes if there are any spaces. The comment is stored and included in output of the hostList command.

Examples

Create a second management instance by adding a new host to the model with a set of installations and instances identical to those on the existing host (specified in the -like option). This command is run from the first management instance, which is on the first host, mysys1host (defined earlier, in the example for Create a Grid (gridCreate)): 

% ttGridAdmin hostCreate mysys2host -internalAddress intmysys2.example.com 
-externalAddress extmysys2.example.com -like mysys1host -cascade 
Host mysys2host created in Model
Installation installation1 created in Model
Instance gridmgmt1 created in Model

This defines gridmgmt1 on mysys2host, duplicating gridmgmt1 on mysys1host.

Create a host for a data instance, specifying the data space group:

% ttGridAdmin hostCreate mysyshost3 -internalAddress intmysys3.example.com 
-externalAddress extmysys3.example.com -dataSpaceGroup 1
Host mysyshost3 created in Model

Notes

  • In specifying host addresses, for each host use the same format—fully qualified domain name, host name, or IP address—as was used in the gridSshConfig command for that host. For example, do not specify mysys1 for hostCreate if mysys1.example.com was specified for gridSshConfig.

  • You can use hostModify to change some settings later.

  • Hosts on the grid may be configured with either one or two network addresses, depending on system topology. If configured with two addresses, one is used for communications with systems inside the grid (internal) and one is used for client/server access to databases inside the grid from systems outside the grid (external). If configured with one address, which is not recommended for production environments, it is used for both internal and external communications. You must either set -address or set -internalAddress and -externalAddress.

Delete a Host (hostDelete)

The hostDelete command removes a host from the model. 

ttGridAdmin hostDelete name 
                       [-cascade]

Options

The hostDelete command has the options:

Option Description

name

Name of the host object to remove from the model.

-cascade

Specifies that installation and instance objects associated with the host should also be removed from the model.

Examples

This deletes a host that was created in an example in Create a Host (hostCreate). 

% ttGridAdmin hostDelete mysys2host -cascade
Instance gridmgmt1 on Host mysys2host deleted from Model
Installation installation1 on Host mysys2host deleted from Model
Host mysys2host deleted from Model

Notes

  • If the host has any installations or instances, you must either use -cascade or use installationDelete and instanceDelete.

  • Deleting instances and installations removes the objects from the model but does not remove the physical instances and installations.

Execute a Command or Script on Grid Hosts (hostExec)

The hostExec command runs a command (such as a system command or TimesTen command) or a script on hosts in the grid, as specified. 

ttGridAdmin hostExec [-only hostname]
                     [-exclude hostname]
                     [-parallel n]
                      command | -script filepath

Options

The hostExec command has the options:

Option Description

-only hostname

The command or script is run only on the specified hosts. Specify just one host with -only, but you can use -only multiple times on the command line.

Use host names as defined in the model.

Without -only or -exclude, the command or script is run on all hosts in the model.

-exclude hostname

The command or script is performed on all hosts in the grid except for the specified hosts. Specify just one host with -exclude, but you can use -exclude multiple times on the command line.

Use host names as defined in the model.

Without -only or -exclude, the command or script is performed on all hosts in the model.

-parallel n

Specifies that the command or script runs on no more than n hosts simultaneously. The default is 10. A value of 1 results in serial execution.

command | -script filepath

command specifies a command to run.

Or:

-script filepath specifies the path and name of a shell script to run. The script must be on the local system, then is copied to each host.

Examples

This example first shows the existing hosts in the grid, then uses hostExec to run the df / command (to show disk space) on each host, excluding mysys3host and mysys4host. So the command is performed on mysys1host and mysys2host. 

% ttGridAdmin hostList
Name        IntAddress             ExtAddress             DSG Comment
----------- ---------------------- ---------------------- --- -------
mysys1host  intmysys1.example.com  extmysys1.example.com    1
mysys2host  intmysys2.example.com  extmysys2.example.com    2
mysys3host  intmysys3.example.com  extmysys3.example.com    1
mysys4host  intmysys4.example.com  extmysys4.example.com    2

% ttGridAdmin hostExec -exclude mysys3host -exclude mysys4host df /
Commands executed on:
  mysys1host rc 0
  mysys2host rc 0
Return code from mysys1host: 0
Output from mysys1host:
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/xvda2           173483816  28416336 136254988  18% /
Return code from mysys2host: 0
Output from mysys2host:
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/xvda2           117144964  35319512  75874836  32% /

Notes

  • The command or script is run on each host as the instance administrator through passwordless SSH.

  • No environment variables are set on the hosts, other than those set by SSH by default.

  • The command returns 2000 if execution did not complete prior to the timeout.

  • During execution, stdout and stderr output is displayed as part of the stdout and stderr output from the hostExec command. Because output is buffered, the output from different commands is not intermingled.

List All Hosts in the Model (hostList)

The hostList command lists information about hosts in the specified version of the model. 

ttGridAdmin hostList [-latest|-current|-version n]

Options

The hostList command has the options:

Option Description

-latest

Lists hosts in the latest model—the model being modified and not yet applied to the grid. This is the default.

-current

Lists hosts in the current model—the model most recently applied to the grid.

-version n

Lists hosts in the specified version number of the model.

Examples

The following two examples, relating to examples shown in Modify a Host (hostModify) and List Model Versions (modelList), show identical output, indicating that version 4 is the latest version (the version not yet applied to the model).

For each host, the host name, internal address, external address, and associated data space group are listed (optionally with a comment).

% ttGridAdmin hostlist
Name        IntAddress             ExtAddress             DSG Comment
----------- ---------------------- ------------------     --- --------------------
mysys1host  intmysys1.example.com  extmysys1.example.com    1
mysys2host  intmysys2.example.com  extmysys2.example.com    1
mysys3host  intmysys3.example.com  extmysys3.example.com    1 Move from location1.
mysys4host  intmysys4.example.com  extmysys4.example.com    2

% ttGridAdmin hostlist -version 4
Name        IntAddress             ExtAddress             DSG Comment
----------- ---------------------- ------------------     --- --------------------
mysys1host  intmysys1.example.com  extmysys1.example.com    1
mysys2host  intmysys2.example.com  extmysys2.example.com    1
mysys3host  intmysys3.example.com  extmysys3.example.com    1 Move from location1.
mysys4host  intmysys4.example.com  extmysys4.example.com    2

Modify a Host (hostModify)

The ttGridAdmin hostModify command modifies a host object in the model. 

ttGridAdmin hostModify name
                       [-dataspacegroup n]
                       [-nodataspacegroup] 
                       [-comment comment]

Options

The hostModify command has the options:

Option Description

name

Name of the existing host object to modify.

-dataspacegroup n

Specifies the number of the data space group that this host will belong to. The number of data space groups a grid will have is determined by the k value set for the grid.

A host with a data instance should always belong to a data space group.

-nodataspacegroup

Specifies that this host will not be part of any data space group (the default)

-comment comment

Associates a comment with the host object or modifies an existing comment. Put the comment in quotes if there are any spaces. The comment is stored and included in output of the hostList command.

Notes

  • The host system must be accessible through passwordless SSH at the time hostModify is executed.

  • If modelApply has already been run for a model including this host, you cannot change the data space group assignment.