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backup concept(user managed) [message #289472] Sat, 22 December 2007 02:52 Go to next message
Vivek.k.thakur
Messages: 30
Registered: December 2007
Location: DELHI, INDIA
Member

Dear all,
hi! plese tell me , when we fire command ALTER TABLESPACE ........BEGIN BACKUP, oracle server freeze the header of the data file, simultaneously users applying DML's on it, where the server process writes ? some people say it updates datafile and some says, that this information is written in log files. I am totally confuse about this concept. Please tell me that how this processing accomplishes. And which oracle background process does perfom these all activities. Means which one background process freeze the header.


Thanks
Vivek Kumar
Re: backup concept(user managed) [message #289473 is a reply to message #289472] Sat, 22 December 2007 03:13 Go to previous messageGo to next message
Michel Cadot
Messages: 64140
Registered: March 2007
Location: Nanterre, France, http://...
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Quote:

where the server process writes ?

In datafiles.

Quote:

it updates datafile and some says, that this information is written in log files.

Choose the one you will trust.
By the way, Oracle ALWAYS writes modifications in log files. This is the purpose of log files.
In backup mode, Oracle writes the whole block in log files the first time you modify it (after putting the file/tablespace in backup mode), then it writes only the modifications as always.

Quote:

which oracle background process does perfom these all activities.

Writes are usely done by DBWR unless these are direct writes, in this case they are done by those who make direct writes.

Quote:

which one background process freeze the header.

No background process, this is you when you execute the "begin backup".

All is in Database Concepts

Regards
Michel
Re: backup concept(user managed) [message #289474 is a reply to message #289472] Sat, 22 December 2007 03:17 Go to previous messageGo to next message
Mohammad Taj
Messages: 2412
Registered: September 2006
Location: Dubai, UAE
Senior Member

http://www.orafaq.com/wiki/User_Managed_Online_Backups
http://www.dizwell.com/prod/node/10
http://www.fortunecity.com/skyscraper/oracle/699/orahtml/oracle/10bullet.html


hope this help
Re: backup concept(user managed) [message #289475 is a reply to message #289473] Sat, 22 December 2007 03:26 Go to previous messageGo to next message
Vivek.k.thakur
Messages: 30
Registered: December 2007
Location: DELHI, INDIA
Member

Thank you very much sir.
Re: backup concept(user managed) [message #289651 is a reply to message #289472] Mon, 24 December 2007 21:26 Go to previous message
ora_zhp
Messages: 10
Registered: September 2007
Junior Member
http://www.dizwell.com/prod/node/10
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