From Glenn.Travis@sas.com Mon, 24 Sep 2001 15:25:52 -0700 From: Glenn Travis Date: Mon, 24 Sep 2001 15:25:52 -0700 Subject: RE: EMC BCV Splits and Hot Backup mode. Message-ID: MIME-Version: 1.0 Content-Type: text/plain Yes! That did it. Now that I know splits are not instantaneous (atomic), it is perfectly clear why you need 'hot backup' mode (to capture the complete oracle blocks). Thanks everyone! -----Original Message----- Sent: Monday, September 24, 2001 6:02 PM To: Multiple recipients of list ORACLE-L Glenn , even though everything are mirrored , splitting is not instantaneous. When track or block level splitting ( I don't know EMC uses which one. I know Hitachi uses track level splitting ) takes place what happens to the committed transaction which is being flushed to that very same track or tracks....? Only half of the info would be in the split copy. Thats why such copies are said to be in 'inconsistent state'. Neither ORACLE nor software responsible for split knows what pieces are missing. To bring those pieces back you got to merge teh BCV again. So the safest way of creating a copy is to place the tablespaces in hot backup mode. I assume you are quiet familier with Hot backup mode so I won't go in detail but suffice it to say that in the present case the missing pieces are in the log file which should be archived at the end of hot backup and safed off with the backup for recovery purpises. When you recover the database in the BCV you have to apply the archived log file and thus you are supplying the missing piece. Hope this helps. Regards, RS --- Glenn Travis wrote: > Well, yeah. But why is it inconsistent? Please > provide details. As you are with EMC, do you have > any papers which discuss at that level? (not the > process steps, I have those. but why?) > > I know that if only the datafiles are mirrored, then > yes, you must use hot backup as the redo changes > need to be written in full Oracle blocks. But what > if everything (datafiles, redo, control, archive) > are all in the mirrored set? How would anything get > inconsistent by breaking a mirror? > > -----Original Message----- > Sent: Monday, September 24, 2001 4:19 PM > To: Glenn.Travis@sas.com; oracledba@lazydba.com > > > > The reason for split is to get a consistent data > -----Original Message----- > Sent: Monday, September 24, 2001 12:41 PM > To: LazyDBA.com Discussion > > > It is my understanding that the common > implementation of copying an Oracle > database on an EMC using BCVs is this; > > 1) put the source database in BEGIN BACKUP mode for > all the tablespaces, > 2) break the mirror, > 3) put tablespaces in END BACKUP mode > 4) recover on target, or backup the files. > > Question: > Why is it necessary to put the database in 'hot > backup' mode when splitting > a BCV? If it is just like splitting a mirror, why > do you need the database > in hot backup mode at all? Wouldn't it be the same > as losing one side of a > mirrored pair? When that happens, no extra > processing is needed. > > > > > > > -------- > Oracle documentation is here: > http://tahiti.oracle.com/pls/tahiti/tahiti.homepage > To unsubscribe: send a blank email to > oracledba-unsubscribe@LAZYDBA.com > To subscribe: send a blank email to > oracledba-subscribe@LAZYDBA.com > Visit the list archive: > http://www.LAZYDBA.com/odbareadmail.pl > Tell yer mates about http://www.farAwayJobs.com > By using this list you agree to these > terms:http://www.lazydba.com/legal.html > -- > Please see the official ORACLE-L FAQ: > http://www.orafaq.com > -- > Author: Glenn Travis > INET: Glenn.Travis@sas.com > > Fat City Network Services -- (858) 538-5051 FAX: > (858) 538-5051 > San Diego, California -- Public Internet > access / Mailing Lists > -------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an > E-Mail message > to: ListGuru@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). __________________________________________________ Do You Yahoo!? Get email alerts & NEW webcam video instant messaging with Yahoo! Messenger. http://im.yahoo.com -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Sakthi , Raj INET: rajan_sakthi@yahoo.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru@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.com -- Author: Glenn Travis INET: Glenn.Travis@sas.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru@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).