RE: Tablespace Backup question

On Mon, 5 Jun 2000 Colin.Shaw_at_phs.com wrote:

> Actually, no. Oracle continues to write to the file *exactly* the same when
> in hot-backup mode, with the exception of the checkpoint SCN. Also, full
> blocks (not change vectors) are written to the redo log. You can find more
> details about this at various web sites or in Velpuri's Backup Handbook.
> Not sure if it's discussed in the Oracle Docs.

I believe what you're saying, though I would like to at least confirm this. It seems *QUITE* weird to me. What if half a block (say 16k blocksize) had been written, and the OS context switches and then the other process starts reading the file. I mean how does Oracle avoid datafile corruption?

Perhaps based on the SCN, Oracle knows that it needs to cleanup those datafiles for all transactions after a certain point, so doesn't worry about it. When you startup the db from the hotbackup, the files *ARE* corrupted then, but Oracle knows from the SCN where to recover from, and starts reading the redologs and writing those changes to the right places in the datafiles. I guess that might make some sense.

I need to do some reading. Received on Tue Jun 06 2000 - 01:06:49 CDT