Versions of the Cluster Edition earlier than 15.0.3 used a single Backup Server for the cluster, which was a potential bottle neck for dump and load commands.
Cluster Edition version 15.0.3 and later allows a cluster to use multiple Backup Servers with one of these methods:
Dedicated method – each instance is assigned a specific Backup Server.
Round-robin method – at the time of the dump or load command, the Cluster Edition assigns the instance a Backup Server from a group according to availability.
A single Backup Server named SYB_BACKUP
The Cluster Edition stores information about all Backup Servers in sysservers. When you issue a dump or load command from any instance, the Cluster Edition searches sysservers for the name Backup Server entry, SYB_BACKUP. If it finds the SYB_BACKUP entry pointing to a srvnetname entry of $DEDICATED or $ROUNDROBIN, it uses the appropriate Backup Server to perform the dump or load operation.
For example, the “snack” cluster is configured to use the dedicated method, and includes an instance named “cupcake.” Because the SYB_BACKUP entry points to “$dedicated,” the cluster uses the cupcake_BS Backup Server to perform any dump or load:
srvid srvstatus srvname srvnetname srvclass srvsecmech srvcoss srvstatus2 ------- --------- ------------ ----------- ---------- ------------ ---------- ---------- 1 8 SYB_BACKUP $dedicated 7 NULL NULL 2 2 8 cupcake cupcake 7 NULL 1000 4 3 8 cupcake_BS cupcake_BS 7 NULL 0 2 4 8 cookie cookie 7 NULL 1000 4 5 8 cookie_BS cookie_BS 7 NULL 0 2
If the snack cluster was configured for the round-robin method, the cupcake instance would use the first available Backup Server to perform dump and loads.
When you upgrade, the Cluster Edition adds entries for all Backup Servers to sysservers.
Entries for Backup Servers are removed from sysservers when you remove an instance from the cluster.
