The only place I can think of redo log size being an issue is if you have a standby. If you are transferring 10g files across the network to a standby, I could see the network getting overloaded. Cant think of anyplace else where that may be a problem. just remember to create sufficient redo log groups that they can be copied off to archive logs before the groups wrap around. On Mon, Dec 9, 2013 at 11:36 AM, Chris Taylor < christopherdtaylor1994@xxxxxxxxx> wrote: > My client has a production database that is hitting 150-160 redo log > switches PER HOUR during the hours of 1-3 am. This is database that is > loaded thru an nightly ETL process where tables are truncated and reloaded > from the source. Average redolog switches during nightly processing is 50+ > but during the day we see reasonable switches of 0,2,4 or 6 per hour. > > Performance is a concern and as expected we are seeing logfile switch > completion in the top 5 wait events during those periods. > > Current RedoLog sizes are 300MB. If I take Oracle's recommended 4 per > hour then we are at approximately 38.75x above the recommended value. I'd > like to get the redo log switches down to 4-6 per hour but that means > resizing my redologs to about 10GB per log member. > > I'm going to set archive_lag_target to a 15 minute interval, but I'm > concerned that 10GB might be "too big". I can't think of a technical > reason why but I've got a nagging feeling that I might be overlooking > something. > > I was thinking there might be a negative impact to backups, but logically > the amount of archive log data being backed up for the same period should > be similar (whether its many ~300 MB archived logs or few ~10GB archived > logs). > > The filesystems in question reside on a NetApp appliance and the > filesystems for database files and the backup location are NFS mounted. > > Is there any obvious thing I'm missing here? I'm going to reduce the > count of redo log files while increasing the size (that's the plan anyway). > I plan to have a couple of additional groups to take into account any slow > archiving so that I should have a "spare" redolog group in case Oracle > tries to wrap around to a group that is being archived. > > Thoughts? > > Chris Taylor > -- Andrew W. Kerber 'If at first you dont succeed, dont take up skydiving.'