ASAP 1.1 Hybrid Manual

HP NonStop ASAP Hybrid Manual – 529729-004
Page 3-24
Recovery
ASAP Hybrid for Linux incorporates mechanisms to prevent the loss of metric
data in the event of a failure of either a client application or the ASAP Hybrid for
Linux server itself.
Client Recovery
If a client application stops or fails for any reason, without first removing all
domains it has registered, the data for those domains is preserved by the Hybrid
for Linux server. When the application is restarted and reregisters the domains, it
is reconnected to the preserved domain data. Application failures do not result
in the loss of valuable metric information. In addition, this feature permits
applications to be stopped and restarted when necessary without requiring that
metric values be reset. This feature can be particularly useful if an application
needs to be taken down temporarily in order to make a configuration change or
to install a new version of an application component.
If an application stops or fails without removing all domains, those domains are
marked as down by the Hybrid Linux server, and appropriate alerts are issued by
NonStop ASAP.
ASAP Hybrid for Linux Server Recovery
If the ASAP Hybrid for Linux server fails or is stopped for any reason, all domain
data remains active. Client applications can continue to update data item values,
set the operational state of domains, and even remove domains while the server
is down. The only thing applications cannot do in this case is register new
domains because registration requires that the server be running. When the
server is restarted, it automatically rediscovers all active domains and begins
communicating that data to NonStop ASAP.
This feature lets client applications continue to collect metric data even if the
server is not running and also allows the server to be upgraded to a new version
without impacting running applications.