| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
 |
 | |||
| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
|
| |||
Home -> Community -> Mailing Lists -> Oracle-L -> RE: MS SQL hasn't given up!
The txn log is just a separate database file(s) and they can autogrow in
increments (MB or %). The growth can be unrestricted or restricted to a
fixed MB size. Though command line TSQL can create the files with space
allocated in units (KB/MB/GB/TB). The wizard isn't quite as flexible. There
can also be multiple transaction log files though I believe the virtual log
files (logs within logs) extended through the additional files as needed as
opposed to the circular log jumping that happens in Oracle.
I think it is important as Oracle DBA's we have at least a conceptual knowledge of what SQL Server can and cannot do. So when management says they want to switch to SQL Server you have something to back up your opinions. I ran into this where the management was MSS/Win2K focused to the max I had to battle against them and the MS marketing guy. I won but it was a lot of work to prove my case. Actually, used application porting time/costs/metrics as DBMS/OS capabilities was a much harder sell.
>From: STEVE OLLIG <sollig_at_lifetouch.com>
>Reply-To: ORACLE-L_at_fatcity.com
>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>Subject: RE: MS SQL hasn't given up!
>Date: Fri, 28 Feb 2003 12:49:29 -0800
>
>no problem Rich. the transaction log mirroring can be done by the DBMS.
>and SQueal Server has disk devices much like a tablespace that can be
>placed
>on different disks and such. transaction logs are kind of like tables in
>that they must be placed in a device. so yes, these mirrored transaction
>logs can be kept apart and "safe".
>
>Rachel's comment is also accurate however. if things go way wrong (usually
>happens to a novice dba) the transaction log can get stuffed so full that
>there's no way to "archive" it and you end up "truncating" it. users tend
>not to like it when they can't do DML ;-) anyway, once a transaction log
>has been truncated there is no transaction recovery until the next database
>backup completes. and yes - the database backup utility does hot backups.
>
> > -----Original Message-----
> > From: Jesse, Rich [SMTP:Rich.Jesse_at_qtiworld.com]
> > Sent: Friday, February 28, 2003 1:47 PM
> > To: Multiple recipients of list ORACLE-L
> > Subject: RE: MS SQL hasn't given up!
> >
> > Steve, when you say "mirror" are the writes duplicated from SQueaL
>Server
> > or
> > hardware? My DBA instructor had distributed some e-mails from a student
> > who
> > left the mirroring of redos up to hardware. One controller firmware
>patch
> > is all it took to corrupt both copies of the redos.
> >
> > So, if the mirror is done at the hardware level, it wouldn't be the same
> > as
> > Oracle. Also, if the TX logs are in the DB, how separated can the
>mirrors
> > be?
> >
> > Hope this isn't getting too off-topic. I just want to make sure that
>I'm
> > not burning any bridges by refusing to let SQueaL Server get any more
>DBs
> > here...
> >
> > Thx!
> > Rich
> >
> >
> > Rich Jesse System/Database Administrator
> > rich.jesse_at_qtiworld.com Quad/Tech International, Sussex, WI
>USA
> >
> >
> > -----Original Message-----
> > Sent: Friday, February 28, 2003 1:19 PM
> > To: Multiple recipients of list ORACLE-L
> >
> >
> > Rich - on your first point - that's why you would choose to mirror the
> > transaction log in SQeal Server. Same effect.
> >
> > the transaction log is a fixed size. it can be extended while the db is
> > online. but shrinking it is quite a bother (at least was back in the
>day
> > -
> > it's been a while). if the transaction log fills up all DML stops.
> > database still recoverable though. just need to clean out or extend the
> > log
> > and all is well again.
> >
> > no snapshot too old errors though ;-)
> >
> > > -----Original Message-----
> > > From: Jesse, Rich [SMTP:Rich.Jesse_at_qtiworld.com]
> > > Sent: Friday, February 28, 2003 12:14 PM
> > > To: Multiple recipients of list ORACLE-L
> > > Subject: RE: MS SQL hasn't given up!
> > >
> > > Yes and no. If your logs are backed up every 30 minutes, then you are
> > > effectively saying that you are willing to lose up to 30 minutes of
> > > transactions, in the event of failure on the TX logs (e.g. hardware).
> > > OTOH,
> > > Oracle can easily be made to be completely recoverable up to the last
> > > transaction ("no data lost") by duplicating, triplicating, etc. both
>the
> > > online redos and the archives.
> > >
> > > Also, isn't the transaction log area in SQueaL Server in the DB itself
> > and
> > > at a fixed size (as opposed to Oracle, where you can add redo groups
> > > on-the-fly)? In other words, if it fills up, what happens? Does it
>get
> > > overwritten or does the DB continue in an unrecoverable mode?
> > >
> > > Trying to understand more of this wonderful Enterprise product...
> > >
> > > Rich
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.net
> > --
> > Author: Jesse, Rich
> > INET: Rich.Jesse_at_qtiworld.com
> >
> > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > San Diego, California -- Mailing list and web hosting services
> > ---------------------------------------------------------------------
> > To REMOVE yourself from this mailing list, send an E-Mail message
> > to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
> > the message BODY, include a line containing: UNSUB ORACLE-L
> > (or the name of mailing list you want to be removed from). You may
> > also send the HELP command for other information (like subscribing).
>--
>Please see the official ORACLE-L FAQ: http://www.orafaq.net
>--
>Author: STEVE OLLIG
> INET: sollig_at_lifetouch.com
>
>Fat City Network Services -- 858-538-5051 http://www.fatcity.com
>San Diego, California -- Mailing list and web hosting services
>---------------------------------------------------------------------
>To REMOVE yourself from this mailing list, send an E-Mail message
>to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
>the message BODY, include a line containing: UNSUB ORACLE-L
>(or the name of mailing list you want to be removed from). You may
>also send the HELP command for other information (like subscribing).
>
-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: david davis INET: ddoralist_at_hotmail.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Fri Feb 28 2003 - 15:34:32 CST
 |
 |