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Re: Datafile Resize/Max Extents Question

From: Connor McDonald <connor_mcdonald_at_yahoo.com>
Date: Fri, 21 Dec 2001 21:17:35 +0000
Message-ID: <3C23A6EF.3BCB@yahoo.com>


Gary Luck wrote:
>
> postbus_at_sybrandb.demon.nl (Sybrand Bakker) wrote in message news:<a20d28ee.0112190042.7b08e68b_at_posting.google.com>...
> > klokwerks_at_yahoo.com (Gary Luck) wrote in message news:<1b60dac2.0112181014.3e13c49b_at_posting.google.com>...
> > > Firstly, I'm new to Oracle and I'd like to thank everyone that contributes to
> > >
> > > this newsgroup- you have helped me immensely.
> > >
> > > I have an Agilent Chemstor database running Oracle 7.3.4 on NT 4.0SP6a. When
> > >
> > > it was initially set up, the main data collecting tablespace was created
> > >
> > > thusly:
> > >
> > > 15 datafiles of 2GB each
> > > 'last' datafile set to extend to 16GB by 1GB increments
> > >
> > > The company is only doing cold backups right now- once every Sunday afternoon
> > >
> > > the database is manually shutdown and backed up to tape using Backup Exec
> > >
> > > 8.6. After testing disaster recovery scenarios with Backup Exec it was found
> > >
> > > that using hot backups, the database was not recoverable. When I was hired,
> > >
> > > I was tasked with making hot backups work. I have written a sql script to
> > >
> > > perform the hot backups and run nightly using NT's 'at' command. This is
> > >
> > > running wonderfully on a replica test box I have been using. The only
> > >
> > > problem is, it is taking a little over five hours nightly because of all of
> > >
> > > the 'empty' data I'm backing up. There is one datafile that has been filled
> > >
> > > and one other that is about half-filled(1GB). So essentially, I'm backing up
> > >
> > > 30GB to get 3GB of data.
> > >
> > > On my test system I resized the empty datafiles to 200MB each and set extents
> > >
> > > of 200MB to a maximum size of 2GB each. I used Oracle's Storage Manager to
> > >
> > > do this and it worked seemlessly.
> > >
> > > My question is this(finally):
> > >
> > > This will give me about 135 extents for this single tablespace- is that too
> > >
> > > many? Also, should I use Server Manager or SQLplus to resize the datafiles
> > >
> > > instead of Storage Manager? What should I do about the 'last' datafile that
> > >
> > > is set to extend to 16GB? That seems inexcuseable to me.
> > >
> > > Again, thanks to all.
> > >
> > > Later, gary.
> > > klokwerks_at_yahoo.com
> >
> > First of all: get away from 7.3.4. It has been desupported for almost
> > a year now, and newer versions have better facilities to deal with
> > your problems.
> > Rman in version 8.0 and beyond is capable of backing up only the
> > changed blocks (instead of the full 30G). This would make this whole
> > discussion more or less academical.
> > Secondly: as this is 7.3.4 space management is very costly. The number
> > of free extents highly depends on how often your tables extend. I
> > would consider it more important those free extents match extents to
> > be allocated in size.
> > I don't think NT is ever going to allow 16G datafiles. It might have a
> > limit of 2G.
> > It doesn't matter whether you use sql*plus or svrmgr23 to resize your
> > datafiles. The command is part of the sql language. I would choose
> > sql*plus for it's editing facilities
> >
> > Hth
> >
> > Sybrand Bakker
> > Senior Oracle DBA
>
> Thanks for the response...
>
> I can't get away from 7.3.4- its a canned package for the Chemstore
> product from Agilent. I would love to go to 8, but they don't produce
> a version of Chemstore on it yet.
>
> I checked my max extents for each tablespace and they are set to 249
> so I'm assuming I'm in good shape there. As for the datafile set to
> grow over 2GB- do you think I should bring this down to 2GB for max
> extent size and then add new datafiles to the tablespace when the need
> arises?
>
> Again, thanks much.

If you can't get off 7.3.4, why not have more tablespaces - so the unit of backup (ie tablespace) is smaller. You could backup a subset of the database each night

hth
connor

-- 
==============================
Connor McDonald

http://www.oracledba.co.uk

"Some days you're the pigeon, some days you're the statue..."
Received on Fri Dec 21 2001 - 15:17:35 CST

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