Description
The REMOTE_HOST option specifies a comma-delimited list of one or more hosts upon which a command can run.
Each host in the list can be specified as a host name or an IP address in dotted decimal notation.
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For purposes of this discussion, even if one host is specified, it is considered a list with a single entry. |
If multiple hosts are specified, the UCMD Manager will try each one until it successfully connects to a Universal Broker. When a successful connection is established, no more hosts in the list are tried. If the UCMD Manager is unable to establish a connection to a Universal Broker on any of the hosts in the list, the UCMD Manager will fail.
Each host in the REMOTE_HOST list also can include a port number or service name that the UCMD Manager will use to establish a connection with the Universal Broker on that host. This is useful in situations where the remote Broker is configured to accept incoming connections on a port that is different from the UCMD Manager's configured value.
UCMD Manager automatically removes any duplicates found in the list of hosts before it makes its first connection attempt. This includes any host names that resolve to the same IP address, or duplicate IP addresses that are added to the list following DNS expansion (see the
DNS_EXPAND option).
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Duplicate IP addresses may appear in the resolved, expanded, scrubbed list of hosts if a different port number is specified for each occurrence of a particular IP address (for example, 192.168.1.1:7887 and 192.168.1.1:7888 are considered distinct entries). |
To set configuration options that control selection of the hosts in the REMOTE_HOST list, see the
HOST_SELECTION and
CONNECT_TIMEOUT options.
To set configuration options that control processing of the hosts in the REMOTE_HOST list, see the
DNS_EXPAND and
MFT_SAFE_MODE options.
The following text briefly describes each of these options.
HOST_SELECTION
UCMD Manager uses the
HOST_SELECTION option to control which host in the REMOTE_HOST list is selected first. UCMD Manager can be configured to always select the first host or to select a randomly chosen host as it begins its attempts to connect to a remote Universal Broker. In either case, after a host is selected, UCMD Manager processes the list sequentially until either a connection succeeds or all hosts in the list have been tried.
CONNECT_TIMEOUT
UCMD Manager uses the
CONNECT_TIMEOUT option to specify how long it will wait for a connection attempt to succeed before it moves on to the next host in the list.
DNS_EXPAND
To set configuration options that control processing of the hosts in the REMOTE_HOST list, the
DNS_EXPAND and
MFT_SAFE_MODE options are provided.
The
DNS_EXPAND option controls the number of IP addresses returned when UCMD Manager issues a DNS query to resolve a host name. If the Manager is configured to expand the results of the query, all IP addresses defined for a particular host name are returned and expanded (in-place) within the list of hosts. Otherwise, only the first host is returned, and no expansion is performed.
MFT_SAFE_MODE
The
MFT_SAFE_MODE option controls the situations in which more than one host may be specified in the REMOTE_HOST list when manager fault tolerance (MFT) is enabled. Automated restarts may result in an MFT restart being tried on a system that is different from the original system. If a restartable MFT process is not found on that system, new work may be started. The
MFT_SAFE_MODE option guards against duplicate processing in this situation.
Usage
Method | Syntax | IBM i | UNIX | Windows | z/OS |
Command Line, Short Form | -i hostlist |
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Command Line, Long Form | -host hostlist |
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Environment Variable | UCMDHOST hostlist | | | |
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Configuration File Keyword | host hostlist | | | | |
STRUCM Parameter | HOST(hostlist) | |
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Values
hostlist is a list of one or more hosts, in the following format:
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host1\[\[:port1\],host2\[:port2\],host3\[:port3\],...hostn\[:portn\]\] |
In this format:
- host is the IP address (in dotted decimal notation) or host name of the system upon which the command may run.
- port is an optional port number (or service name), which is necessary only if the remote Universal Broker is accepting incoming connections on a port that is different from the value specified by the REMOTE_PORT option.
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The port number, when specified, must be separated from the host by a colon ( : ). |
| Info |
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| Only a single host can be specified, either as an IP address in dotted decimal notation or a host name. In addition, a port number only can be specified with the REMOTE_PORT option. Specifying a port number in the host list is not supported. |
