Re: Logical Logs on OWS 7.20 UC2

ramp wrote: > > What i don't know is what happen when the logical logs get full in a not > transactional evironment and with then devicel for logical logs set to > /dev/null . I will get a dead lock or the logs get empty when On-Line > need more space. If the LTAPEDEV=/dev/null then online acts as if ontape -a is always running and marks each log "backed up" as it is completed, in 7.xx+ the log is not actually freed until it is needed for reuse and can only be freed if there are not active transactions contained in that log. You can only get deadlocked on logs, in this case, if a single transaction spans all of the log files so that none can be freed when they are needed for reuse. In a transaction environment you should have lots of large log files to prevent this. A trick to let you unwind this problem if you do get hung up by long transactions is to set LBU_PRESERVE=1 which will prevent the last log file from being used. Then if things to get stuck you can shutdown, change LBU_PRESERVE=0 and restart forcing a rollback of the hung transaction while freeing the last log file to record the rollback (credit Jake Salomon with this slight of hand) this will work if your log files are each large enough to record the fast recovery and rollback information. Once the offending transaction has rolled back all of the other log files will be freed. Art S. Kagel