On Wed, 10 Feb 2016 13:28:12 +0100, R.S. wrote: > Peter, > You are right, active log is copied to archlog, but after that the > actlog is "in scratch status", that mean it can be reused. > It is very similar to SMF SYS1.MANx datasets. > > And yes, after succesful copy actlog -> archlog the data will be > searched in archlog. Actlog is logically empty (until reuse). >
No, an offloaded active log dataset is only marked "reusable". Reusable logs are used as far back as possible in rollback/recovery. http://www.idug.org/p/fo/et/thread=23811 http://www-01.ibm.com/support/knowledgecenter/SSEPEK_11.0.0/com.ibm.db2z11.doc.admin/src/tpc/db2z_retrievelogrecords.dita "Log records are retrieved by DB2 through the following events: - A log record is requested using its RBA. - DB2 searches for the log record in the following locations in the order in which they are presented: 1. The log buffers. 2. The active logs. The bootstrap data set registers which log RBAs apply to each active or archive log data set. If the record is in an active log, DB2 dynamically acquires a buffer, reads one or more CIs, and returns one record for each request. 3. The archive logs. DB2 determines which archive volume contains the CIs, dynamically allocates the archive volume, acquires a buffer, and reads the CIs." https://www-01.ibm.com/support/knowledgecenter/SSEPEK_10.0.0/com.ibm.db2z10.doc.inst/src/tpc/db2z_activelogdsstgreqs.dita "When DB2 fills up one active log data set, it must offload the log data to an archive log data set. At the same time, DB2 begins writing to the next active log data set. When DB2 reaches the last active log data set, it starts again with the first active log data set." A reusable log is an active log data set. The RBA range for a reusable log is in the BSDS (see DSNJU004/print log map http://www-01.ibm.com/support/knowledgecenter/SSEPEK_10.0.0/com.ibm.db2z10.doc.ugref/src/tpc/db2z_dsnju004output.dita ) > Regarding buffers I think you ar wrong. Buffers are heavily used for > tables, but not for log. Due to transaction integrity active log is > immediately written to DASD. http://www-01.ibm.com/support/knowledgecenter/SSEPEK_11.0.0/com.ibm.db2z11.doc.admin/src/tpc/db2z_howcreatelogrecords.dita Norbert Friemel ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
