Re: Backup trends (2): HOT or COLD

Mark Bole <makbo_at_pacbell.net> wrote in message news:<Awgmc.60702$aT2.30940_at_newssvr25.news.prodigy.com>...

<SNIP>
>
> Myth #1. RMAN only backs up those datablocks which contain data.
> Myth #2: Incremental backups will take significantly less time to backup
> than full backups.
> Myth #3: I can specify incremental backups during a restore operation.

One of the myths I know is the one mentioned earlier about 'RMAN doesn't back up EMPTY blocks' This is a wee bit misleading as, at 9iR2 anyway, it doesn't backup up VIRGIN blocks.

If you create a table with a decent initial size and put no data in it, RMAN won't backup much other than the header (I assume!).

If you now fill it with data and get the HWN moving, RMAN will, obviously, backup the table up to the HWM.

Now delete the data (which leaves the HWM where it is) and RMAN still backs up the table up to the HWM because although the blocks are empty, they are not virgin any more (!).

So the empty thing can lead some people up the garden path.

All I need now is Howard to tell me I'm wrong again :o)

Cheers from behind the firewall :o(

Norm. Received on Thu May 06 2004 - 11:36:37 CDT