One of my databases is very large. Full exports take 13 hours and hot backups take 8. We do them daily, one after the other without overlap.
But soon, more data will be added and I won't be able to squeeze them both in a single day. Does anybody have any experience with running them at the same time? Some of my tables are quite large, and I am using consistent=Y.
Thanks for your responses.
03-01-2001, 11:46 AM
Avoid hot backup and export concurrently.
You can adopt round robin tablespace hot backup.
I think you have insufficient hardware ( disk controllers, disks, tapes). If this is the case, first add enough hardware in order to minimize the backup time.
03-01-2001, 12:32 PM
I agree with you 100% that we need more hardware... it's in the works. But my problem will most likely occur before anything can be done.
Is it bad because of the fact that consistent exports make a lot of rollback, and when the rollback tablespace is getting hot-backed then there is contention? Is it unsafe or just not good practice?
I don't intend to do this long term - just for a little while until we can get better hardware.
03-01-2001, 05:42 PM
I suggest start using RMAN becuase RMAN will wait for DBWR to complete its work before the data block is copied into backup drive. Do not use your own hot backup script if the DB is huge. That way you can reduce creating many archived redo log files.
03-01-2001, 05:48 PM
Yes, we are going to start using RMAN down the road, but like the hardware, we probably won't be able to implement it before this surge of data hits. we have literally hundreds of databases where I work of all shapes and sizes. we like to keep the backup strategy the same, so going to RMAN is not so easy as it would be if we just had a few databases to work with.
So my questions remain -
Are concurrent hot backups and exports bad because of the fact that consistent exports make a lot of rollback, and when the rollback tablespace is getting hot-backed then there is contention? Is it unsafe or just not good practice?
03-01-2001, 06:39 PM
Your exports dont serve any production purpose if you have hot backups.
If you are taking exports because of a fear that some object may be lost / dropped, then go ahead and do an inconsistent export and worry about the inconsistencies later
If the export is for an import into a dev database etc., do you really need to do it every day?
03-01-2001, 08:42 PM
why don't you use incremental export? so you don't need to export whole DB, but just the data changed within one day. RMAN can do similar incremental backup.
by the way, you can also do parallel backup to speed up, if you have several backup destanations or tape drives.
03-01-2001, 10:32 PM
In case of large tables, incremental exports will not do any good since incremental export only exports at the table level and not at the row level.