Re: Enabling Archivelog mode, Oracle7- any issues?

"Thomas T" <T_at_T> wrote in message news:3f565f45$1_at_rutgers.edu...
> So I've read books, online docs, and even found Howard Rogers' "Backup &
> Recovery Workshop" document.
>
> I've got a Novell 5 server running an Oracle7 database, on Novell 5, which
> has not been in archivelog mode since Oracle6. It's one of those things
> that I've meant to look at, and in cleaning off my desk (!), I've been
> reminded of it. We take cold backups nightly; the database doesn't see
much
> in the way of transactions- and when it does, we always grab a before &
> after export file. But it'd be nice to be able to take hot backups, and
let
> the library cache and buffer cache fill up with "useful" things instead of
> re-filling themselves each morning.
>
> Are there any issues with turning archivelog mode on? Everything I've
read
> says to "issue these statements and it's done." Granted, I don't doubt
what
> I've read; I'd just like to hear some feedback/opinions from actual DBA's.
>
> Seems like this is all I have to do from server manager:
>
> connect internal (remember, Oracle 7.3, no fancy 9i here...)
> startup mount
> alter database archivelog
> alter database open
> alter system archive log start to 'vol1:oranw_d2\archives'
>
> Then I'd issue a shutdown, perform a cold backup to tape, and finally, go
> into my init.ora and add the following commands:
>
> log_archive_start=true
> log_archive_dest=vol1:oranw_d2\archives
> log_archive_format=arc%s.%t (really the Oracle7 default, but might as
well
> type it in)
>
> After which, I load up server manager again, and issue the startup
command.
>
> I mainly have one question about the above procedure- the alter system
> archive log start command. Am I correct in assuming I should add the "to
> (pathname)" parameter? Nothing I've read, save for the Oracle command
docs,
> mention adding that parameter. The docs just say to issue "alter system
> archive log start".
>
> Or, since I'll be shutting the database down immediately to take a cold
> backup, does it matter? There really won't be a chance for an online redo
> log to fill up and write to disk. Even if it did, couldn't I find it on
the
> drive, and move it manually (via the o/s) to the "proposed" future
> log_archive_dest directory?
>
> Or should I just get a jump on things and add log_archive_dest to the
> init.ora before I even put the database into archivelog mode? Then I'd
just
> say "alter system archive log start"? (I believe this to be the right
> answer...?)

You believe correctly.

The reason the doco doesn't say to add the "to" bit to the 'alter system archive log start' command is that there is a default directory where it ends up. It varies, I think, from platform to platform, but generally seems to be (from memory) ORACLE_HOME/dbs/archive. If you end up with some archived logs there, and some others in a different place because you eventually get round to changing the log_archive_dest parameter, then it isn't going to kill you.

But the simplest thing to do is to get log_archive_start and log_archive_dest set in your init.ora when you do your next cold backup. When you restart your database, they will be set and ready to go. If on the way to restarting your database, you were to stop off in mount state, and issue the alter database archivelog command, then by the time you issue the alter database open command, everything will already be working.

>
> *One more question, while I'm at it. It looks like, once the archived
logs
> get put onto tape, I can delete them from the disk. I'd like to delete
them
> after 48 hours. Does that sound reasonable?

Sort of. The more you can keep on disk, the happier you'll be (On the grounds that restoring from tape can be a pain in the bottom, and recoveries done from disk will be quicker, generally, than those from tape. Depends on your tape drive, of course!), But the principle is that you can delete anything if you've got a copy of it somewhere else first.

>Or should I just leave them on
> the disk, keep an eye on disk usage, and delete old logfiles as I see fit?
> What if I need to recover (unlikely!) 96 hours previous- would I restore
the
> previous 48 hours of log files back onto the disk, and that, along with
the
> current 48 hours, would give me my total 96 hours to recover from?

Correct.

>
> Sorry to ask so many questions but I can't seem to find any of this in the
> literature I've read...

I feel I've failed, in that case. But a new paper is on its way, anyway, and I'll take these comments into mind when doing it.

Regards
HJR
>
> Thanks!
>
> -Thomas
>
>
Received on Thu Sep 04 2003 - 05:01:41 CDT