Yeah, I think we're all saying the same thing. I'll just comment on a
couple of your comments about hot backups.
1. I'll say I'm a fan of RMAN. The value of it significantly outweighs
it's cost. True incremental backups (10g+) and two-command
restore/recover are enough. But RMAN has come a long way. RMAN is 8 is
nowhere near as good as it is in 9, and even farther from RMAN in 10g.
2. Recovering from hot backups requires a single command "recover
database." All you need is for the archivelogs that span the time of
the backup to be in the right place, or tell Oracle where they are.
It's the same command that's used to roll last night's cold backup
forward to the point of failure. With a cold backup it's optional; with
a hot backup it's required. If you don't want to roll to current point
in time, you have to add an "until" statement, like "until cancel" or
"until <time>." It's really not that big of a deal.
3. Under normal conditions, the control file's got nothing to do with
the difficulty of recovering from a hot backup. The control file simply
must be more recent than the backup, but that's the same with a cold
backup. Now, if you lost ALL control files (something that should never
happen if you're multiplexing/mirroring them) then yes, you'd have to do
another step if you're recovering from a hot backup.
4. The performance difference (and space difference) while in backup
mode is negligible. It's probably one of the most misquoted and
misunderstood things in Oracle. On the times I've measure it, the
difference was less than 3%, and that was only under extreme load.
I hope this helps our mutual friend. ;)
---
W. Curtis Preston
Backup Blog @ www.backupcentral.com
VP Data Protection, GlassHouse Technologies
-----Original Message-----
From: Jeff Lightner [mailto:jlightner AT water DOT com]
Sent: Monday, July 09, 2007 11:21 AM
To: Curtis Preston; Mike Kiles; VERITAS-BU AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Oracle 8 Backup - NBU6.0 MP4
It appears you misread something. If you're doing RMAN you don't do it
cold at all. I said he had to use RMAN because he said he couldn't
take the DB down (which he would have to do for a cold backup).
Earlier I'd noted that one could do a hot backup but noted that hot
backups are harder to "recover" (not "restore"). This is for reasons
DBAs could tell you but I couldn't - something about the control file.
I guess he could do hot backup mode instead if he can't shut it down but
there is additional work for restore as well as additional logging it
does while in that mode and the performance impact of that logging and
later commits to DB. I've never measured these and given that he's
running Oracle 8 stair-stepping might make hot backup preferable to
RMAN.
In summary I was discussing 3 different things:
Cold backup
DB down - NBU "standard" backup of the filesystem(s) or raw device(s)
containing DB spaces.
Hot backup
DB in "hot backup mode" - NBU "standard" backup of the filesystems(s) or
raw devices(s).
RMAN backup
DB up - RMAN feeding the backup to NBU with Oracle add on using RMAN
repository and RMAN/NBU-ORACLE scripts.
For the record we do the BCV copy of hot backup every day except Sunday
when we do a BCV copy of cold backup. When we write to tape we're
actually doing so from the BCV copy. This is for our 4 TB Production
backup. We have a smaller 300 GB Production that is backed up using
RMAN.
Support is problematical however - does Oracle actually support 8
anymore with RMAN? Will the newer NBU versions support an older RMAN if
that is required for Oracle 8?
I haven't written a book about it so I'm willing to assume you know more
about it than I do. :-)
-----Original Message-----
From: Curtis Preston [mailto:cpreston AT glasshouse DOT com]
Sent: Monday, July 09, 2007 2:04 PM
To: Jeff Lightner; Mike Kiles; VERITAS-BU AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Oracle 8 Backup - NBU6.0 MP4
Jeff, in your previous post, you mentioned backing up the database hot
using the commands he mentioned. Why are you now saying he has to do it
cold and has to use RMAN?
What he's proposing is fine. It's not as good as RMAN (by far), but he
definitely doesn't have to buy the agent just to back up Oracle. The
database must be in archivelog mode for it to work, but he specified
that he's doing that.
1. Login as oracle user
2. connect internal (or as sysdba)
3. alter database begin backup
4. Select * from sys.dba_data_files
(that will give you a complete list of data files to back up)
4. Back up the files/filesystems found in #4
5. alter database end backup
6. alter system archive log current
7. Find out the value of LOG_ARCHIVE_DEST, where archived redo logs are
sent
8. Back up LOG_ARCHIVE_DEST, or at least the files that were created
just before, during, and just after the backup
Shameless plug: This procedure (and how to use RMAN without buying an
agent for it) is covered in my book:
http://www.oreilly.com/catalog/backuprecovery
---
W. Curtis Preston
Backup Blog @ www.backupcentral.com
VP Data Protection, GlassHouse Technologies
-----Original Message-----
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of Jeff
Lightner
Sent: Monday, July 09, 2007 7:13 AM
To: Mike Kiles; VERITAS-BU AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Oracle 8 Backup - NBU6.0 MP4
If you can't shut it down you'll need to use RMAN and the NetBackup
Oracle add on. I can't offer a lot of guidance on that since we do
have DBAs that created the repository it needs and are responsible for
the scripts and cron scheduling - we only created the policy and the
"schedules" (full, incremental etc...) within that which they call from
the scripts. There are sample RMAN scripts with the NBU Oracle stuff.
-----Original Message-----
From: Mike Kiles [mailto:mikekiles AT yahoo DOT com]
Sent: Monday, July 09, 2007 10:04 AM
To: Jeff Lightner; VERITAS-BU AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Oracle 8 Backup - NBU6.0 MP4
Database is not big it is only about 200GB, but we can
not shut it down for backups. We dont have a DBA here,
only some developers who can assist me, but they are
not very familiar with backups.
Thx
--- Jeff Lightner <jlightner AT water DOT com> wrote:
> If you aren't going to set up RMAN you need to do
> backups of the
> filesystem(s) or raw device(s) where the dataspaces
> are defined. The
> best way to do this is with the database completely
> down. This is
> called a "cold backup". You can also do a "hot
> backup" by putting the
> database in "hot backup" mode but that requires more
> effort to get going
> after restore. How large is your DB? For really
> large ones having it
> down long enough for a cold backup or even in hot
> backup mode isn't
> really a good thing. Most shops with really large
> DBs do a BCV/snap of
> the database then do the backup to tape from the
> that BCV/snap copy
> after splitting and restarting the primary DB.
>
> RMAN requires a separate Oracle repository. Do you
> not have Oracle DBAs
> to deal with that part of it?
>
> -----Original Message-----
> From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
> [mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu]
> On Behalf Of Mike
> Kiles
> Sent: Monday, July 09, 2007 9:19 AM
> To: VERITAS-BU AT mailman.eng.auburn DOT edu
> Subject: [Veritas-bu] Oracle 8 Backup - NBU6.0 MP4
>
> Good Day
>
> I have asked to a full backup of our oracle 8
> database
> which is running in archive log mode. RMAN is not
> set
> up and I was told to put the database in backup
> mode.
> I am not a DBA and would appericiate your help if
> someone can tell me the exact commands to run on the
> database server (Tru64) prior to me starting the
> backup and the commands to run after backup is
> finished.
>
> Here is what I was thinking of running prior to
> starting the backup:
> - Login as oracle user
> - connect internal
> - alter database begin backup
>
> After the backup is finished
> - Login as oracle user
> - connect internal
> - alter database end backup
>
> I read some dicussions about switching log files and
> also about backing up control files, but I couldnot
> find out the commands to accomplish thes and where
> to
> put them.
>
> Anything else that I may have missed?
>
> Thanks
>
> MK
>
>
>
>
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