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Home -> Community -> Usenet -> c.d.o.server -> Re: Redo Log Question
And Here is the Official Oracle Word, (which by the way says
MULTIPLEX, MULTIPLEX, MULTIPLEX OFFERS THE HIGHEST LEVEL OF PROTECTION
(KNOWING WE DON'T LIVE IN A PERFECT WORLD) AGAINST BOTH LOGICAL AND
PHYSICAL FAILURE...
This is Oracle's recommendation as documented in the Oracle8i Backup
and Recovery Guide, Chapter 2, Managing Data Structures:
"Oracle provides the capability to multiplex an instance's online redo log files to safeguard against damage. When multiplexing online redo log files, LGWR concurrently writes the same information to multiple identical online redo log files, thereby eliminating a single point of failure. You can also mirror redo logs at the operating system level, but in so doing you run the risk of operating system or hardware induced corruption. In most cases, multiplexing of online logs is best.
Oracle recommends multiplexing the online redo log on separate physical disks or possibly different file systems. If the file systems or disk subsystems support mirroring, this operation adds another level of redundancy. The online redo log is the source of your recovery data. Loss of all copies of an online log can mean the loss of committed transaction data."
"Howard J. Rogers" <howardjr2000_at_yahoo.com.au> wrote in message news:<yAoN9.8372$jM5.23630_at_newsfeeds.bigpond.com>...
> alter database add logfile member '/blah/blah/blah.log4b.rdo' to group 4;
>
> Regards
> HJR
>
> "Chucky" <chuck.carson_at_syrrx.com> wrote in message
> news:3E05D398.7010208_at_syrrx.com...
> >
> > How would I add more logs per group on a database that has already been
> > created and is up and running?
> >
> > Thx,
> > CC
> >
> > Howard J. Rogers wrote:
> > > "Chuckster" <chuckycarson_at_networkcloud.com> wrote in message
> > > news:3E04A739.5020503_at_networkcloud.com...
> > >
> > >>When you have your redo logs created as follows:
> > >>LOGFILE
> > >> GROUP 1 '/u01/oradata/syrlims/redo01.log' SIZE 10M,
> > >> GROUP 2 '/u02/oradata/syrlims/redo02.log' SIZE 10M,
> > >> GROUP 3 '/u03/oradata/syrlims/redo03.log' SIZE 10M,
> > >> GROUP 4 '/u04/oradata/syrlims/redo04.log' SIZE 10M
> > >
> > >
> > > Correct. No redundancy. If you wanted redundancy, it would look like
> this:
> > >
> > > LOGFILE
> > > GROUP 1
> > > ('/u01/oradata/syrlims/redo1a.log','/u05/blahblahblah/redo1b.log') SIZE
> > > 10M,
> > > GROUP 2 ('/u02/oradata/syrlims/redo2a.log','/u06/bbb/redo2b.log')
> SIZE
> > > 10M,
> > > GROUP 3 ('/u03/oradata/syrlims/redo3a.log','/u07/bbb/redo3b.log')
> SIZE
> > > 10M,
> > > GROUP 4 ('/u04/oradata/syrlims/redo4a.log','/u08/bbb/redo4b.log')
> SIZE
> > > 10M
> > >
> > > Extra groups buy you time before you start over-writing earlier logs
> (and,
> > > specifically, buys ARCH time to archive the earlier logs before your try
> and
> > > re-use them).
> > >
> > > Extra members per group buys you resilience and redundancy.
> > >
> > > And I've renamed your original files so that the number indicates the
> group
> > > and the letter indicates the member, which I find easier to manage than
> the
> > > 'official' recommendation of, for example, REDO0101 and REDO0102.
> > >
> > > Regards
> > > HJR
> > >
> > >
> > >>
> > >>This is merely 4 different log files with no redundancy correct? If I
> > >>wanted path redundancy, I would need to add more log files per group and
> > >> make sure they are on different volume groups/spindles correct?
> > >>
> > >>Thanks,
> > >>CC
> > >>
> > >>
> > >>
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Received on Mon Dec 23 2002 - 09:01:49 CST
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