Re: What is Oracle doing during statup?

From: Graeme Barnett <gbarnett_at_csl.co.uk>
Date: 13 Mar 2002 07:17:33 -0800
Message-ID: <47120ba9.0203130717.5dbac978@posting.google.com>

I'll explain better, the system is from a customer, who uses the OFA and therefore has disk1db, disk2db, disk3db. Due to limited space, I've restored the database to one directory and create root symbolic links called disk1db, disk2db, disk3db which point to this one directory.
Could this cause the problem?

I've also changed the init.ora parameters as there was a warning about shared memory in the last log file. But according to the alert log it said 'system parameters with non-default values' and listed the old values.

What is going on?

Ta,
Graeme

-----Original Message-----

From:	David Fitzjarrell [SMTP:DavidF_at_bcgsystems.com]
Sent:	Wednesday, March 13, 2002 3:03 PM
To:	Graeme Barnett
Subject:	RE: Oracle startup activities

If you can't identify the controlfile then, yes, using symbolic links is a problem. You may be restoring the files in the original locations and not restoring the links to them. The files are there, but not where Oracle expects to find them. You'll need to recreate the links (if possible) before this instance will start, I believe.

-----Original Message-----
From: Graeme Barnett [mailto:gbarnett_at_csl.co.uk] Sent: Wednesday, March 13, 2002 9:00 AM
To: David Fitzjarrell
Subject: RE: Oracle startup activities

> Can anyone tell me what Oracle does when it starts up? I'm particularly
> asking as I want to know why Oracle 8 on Solaris is taking around 10
> minutes just to start the instance I've just extracted from a customers
> backup tape. Regards, Graeme
>
> A couple of questions if I may --
>
> Is this a cold or hot backup?
>

        Cold backup.

> How large is the database?
>

        About 6 gig

> Answers to these questions will help determine why the startup takes a
> while. Now, on to what Oracle does during startup:
>
> Oracle begins by allocating sufficient memory to house all of the required
> structures (SGA, PGA, UGA, buffers, etc.) and setting various parameters
> from the init.ora file, i.e., start archive logging, set a utl_file
> directory and so forth. The figures reported on the console reflect these
> settings.
>
> Next Oracle accesses the control files listed in the init.ora file and
> populates the various views/tables with data file information. [If the
> control files are not readable the database will not mount and new control
> files will need to be created.] It also assesses the need for recovery
> based upon the latest checkpoint in the control file and the latest
> recorded checkpoint in each data file. The database is then mounted.
>
> Oracle finally verifies the data files and starts any recovery operations
> necessary to bring them into line with the recorded checkpoints in the
> control files; this can take some time if this was a hot backup and the
> files are numerous and large. Once the recovery is completed the database
> is opened.
>
> This is by no stretch of the imagination a thorough discussion of the
> intricacies of the startup process, however it should give you a good idea
> of what is going on and why it may take a bit of time to actually get an
> instance up and running.
>
>

	Thanks.
	After running for 10 minutes it gives the error ORA-00205: error in
identifying controlfile.
	The alert file contains ORA-205 signalled during: alter database

mount...

        The datafile is present and has the correct permissions. The only 'non-normal' thing that's going on is that it's been accessed via symbolic
links rather than normal directories - this wouldn't cause a problem would
it?

        Cheers,

        Graeme Received on Wed Mar 13 2002 - 09:17:33 CST