Caché Monitoring Guide - InterSystems Documentation

Monitoring Caché Mirroring Performance
Following are descriptions of the mirror journal checkpoint information displayed above:
• LastJrnData — The address of the last journal data written to disk (to the mirror journal file) on each system. On a
mirror that has an active (caught-up) backup, the LastJrnData on the backup should be the same as the LastJrnData on
the primary. Sometimes, however, it is possible to observe the backup being ahead of the primary, and vice-versa, due
to the way the data is presently collected.
• CurJrnChkpnt — Relates to how up to date the databases are with respect to the dejournaling processes on the backup
system. This information is updated periodically, but may not be reported in an up-to-date (to-the-second) format;
however, if the backup is restarted, it begins processing updates from this journal offset.
• MinTransIndex — The journal offset of the earliest open transaction on the primary. This indicates how far back
transaction rollback needs to occur during a failover.
• Journal file — The currently active mirror journal file name.
The last section lists the mirrored databases, including the mirror status, on each node; typically, all databases are listed as
active on each node:
SYSONE SYSTWO SYSASYNC
------------------ --------------- --------------- ---------------
. . .
Mirror Databases:
DBONE: Active Active Active
DBTWO: Active Active Active
96 Caché Monitoring Guide