SQL/MP Installation and Management Guide

Managing a Distributed Database
HP NonStop SQL/MP Installation and Management Guide—523353-004
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Changing Network Environments
quiesced before the communication loss for planned downtime. Transactions on
other nodes will continue, and might not be adversely affected, as a result of local
autonomy, but you might need to use one of the TMF interfaces (such as
TMFCOM) to back out or commit the transactions manually. Transactions requiring
data on the unavailable node return errors. After communication is restored,
transactions can proceed normally.
•
Recovery takes place for a system crash on a single node. If a node crashes, you
can recover it by using a TMF recovery method. HP recommends that you initiate
the START TMF, TRANSACTIONS OFF operation at the crashed node. This
approach enables the TMF subsystem to resolve any network-distributed
transactions active at the time of the crash and to attempt volume recovery.
Keeping TRANSACTIONS OFF during this procedure enables the function to
complete successfully, before new transactions are introduced to the database. If
the node is successfully recovered, transactions can then be turned on. For
additional information, see the TMF Operations and Recovery Guide.
•
A number of situations can cause severe problems with the consistency of a
SQL/MP database. Various techniques can resolve these problems. You should
not, however, attempt these operations without help from your service provider:
°
Recovering a node with distributed objects by using the TIME option of the
TMF subsystem, which can cause an inconsistent database
°
Performing a RESTORE of objects on a node, such that the restored objects
are not consistent with the rest of the database
°
Changing a node name or number by performing a system generation
(SYSGEN)
°
Performing licensed SQLCI2 operations inconsistently throughout the network
catalogs
°
Using the CLEANUP utility on portions of a network database, which can leave
unresolvable references in other catalogs
°
Loading or copying inconsistent data into a network partition
If any situation arises that you think might affect the network-distributed SQL database,
contact your service provider for additional information.