The system database contains information about all database catalogs in the server cluster, configuration of the current server and various memory, network and transaction statistics. 

Tables 

Disk-based Tables 

Tables stored in the system database on disk.

• syscatalogs - Databases in the cluster
• systables - All tables in the cluster
• syscolumns - All columns in the tables of the cluster
• sysindexes - All indexes and keys in the tables of the cluster
• sysprocedures - All procedures in the cluster
• sysinstances - All server instances in the cluster

Registry Table 

This table is derived from information in the registry and startup settings of the server instances.

• sysconfig - A table containing the current server instance configuration

In-Memory Tables 

These are virtual tables generated dynamically to provide information about the current server cluster.

• msessions - Information about the current connection sessions
• mprocesses - Information about the CPU processes
• mnetwork - Statistics on current network connections
• mtables - Performance monitor on tables
• mprocedures - Statistics on stored procedures
• mtransactionlog - Statistics on the transaction logs
• mtransactions - Statistics on current transactions
• mlocks - Statistics on locks for each server instance
• mpagecache - Statistics on page caches of each instance