Re: about archivelog and database status

"Dino Hsu" <dino1_at_ms1.hinet.net> wrote in message news:2i05otomqhaooh8a2oh0gmrm63a23lsjvn_at_4ax.com...
> Dear all,
>
> Quoting a book: (Jason Couchman, p.667)
> "The following code block shows how to put the database into
> archivelog mode:
> SQL> alter database dismount;
> Database altered.
> SQL> alter database archivelog;
> Database altered.
> SQL> alter database open;
> Database altered."

The first line should read alter database mount; <snip>

> I found the following points:
> 1.'alter database close' is used to go from 'open' to 'mount' status,
> but there are some unknown sessions existing that prevents us from
> doing this. We cannot go from 'open' to 'nomount', either. Therefore,
> we can only 'shutdown immediate' and then 'startup mount'.

IIRC Alter database close; is the equivalent of shutdown normal; In other words No new sessions can connect but the database waits for existing sessions to terminate before closing.

> 2.We can go from 'shutdown' to either one of 'nomount', 'mount', or
> 'open' with no problem; we can also go from 'mount' to either 'open'
> or 'nomount'.
> 3.We cannot go from 'nomount' directly to 'open', we have to go to
> 'mount' first and then 'open'.

These two are correct.

The startup process is

1. prepare instance (setup processes and memory structures as per init.ora) <nomount>
2. mount the database. In fact this means mount (or load) the control file. <mount>
3. actually open the datafiles, redo logs etc <open>

steps 1 to 3 are reversed in a shutdown.

Archive log information is recorded in the control file hence the need to issue alter database archivelog at that stage.

--
Niall Litchfield
Oracle DBA
Audit Commission UK



> 4.'alter database archivelog/noarchivelog' can be performed only when

> the database is 'mount', not when 'nomount' or 'open'.


Correct.