Release 10.1B: Progress Fathom Replication
User Guide
Latency
Latency within Fathom Replication is defined as the time between the update being performed on the source database and the update occurring on the target database. Fathom Replication latency depends on several factors, all of which should be taken into consideration:
- The number and frequency of updates to the source database — If the database is frequently updated and the after-image blocks are frequently filled, the latency will be much shorter. If there is little uncommitted activity on the source database, the latency may be longer.
- Network volume availability and bandwidth — If the network is slow or near capacity, the latency between the source and target database increases.
- Target database/machine downtime — The longer the target database or machine is unavailable, the higher the latency will be. If the downtime is expected to be a multi-day event, you should consider disabling Fathom Replication on the source database.
During downtime of the target database or machine, the source/production database is unprotected. If the target is used for read-only access, a down target would mean no read-only access.
Extents must not be deleted if they must be used to roll forward in the event of a failure.
For more information about latency, see Chapter 5, " Reference."
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