DB2Storage Objects 19
• The amount of time to cover with all logs (Time 1 up to Current Time)
• The amount of time to cover with active logs (Time 2 up to Current Time)
Figure5. DB2Log a ndIts Data Sets

3.6.3 Archive Logs

Archive logdat a sets are DB2 managed backups of the activelog data sets.
Archivelog data sets are created automatically by DB2 whenever an active log is
filled. They mayalso be created with the -ARCHIVE command for operational
requirements. Additionalcircumstances may trigger the archiving process. The
DB2 forOS/390 Administration Guide, SC26-8957,describes these in detail.
DB2 supports dual archive logs and it is recommended to use dual archive log
data sets forall production environments. When dual archive log is specified,
during the archiving, the primary active log is read and two archive log data sets
are written in parallel. For better archive log availability,customers sho uldde fine
both copies on differentdevices (or SMS classes) to physically separate the dual
data sets.
Archive logdat a sets are requiredfor any recovery that spans a period of time in
excess of the time coveredby the active logs. Archive log data sets are
sequential data sets that can be:
• Defined on disk or on tape
•Migrated
• Deleted with standard procedures
Archive logdat a sets are requiredfor data integrity. Procedures are required to
ensure that archivelog data sets are only deleted when they are not going to be
required anymore.
This book contains references relatedto archive log deletes, in the following
sections:
• “Deleting Image Copies and Archive Logs” on page 21.
• “Impact of Log Size on Backup and Recovery Strategy” on page 18.
DB2 LOGACTIVE LO GARCHIVE + ACTIVE LOG
Start
Time
Time
1Time
2
Current
Time