RE: BEGIN BACKUP MODE !!

From: Christopher Spence <cspence_at_FuelSpot.com>
Date: Tue, 02 Oct 2001 06:47:19 -0700
Message-ID: <F001.0039E9A0.20011002054520@fatcity.com>

It freezes increasing the SCN of the data files associated with the tablespace. Then it writes full block data to the redo logs instead of the standard old, new, operation data. If the block has already been written out, it will use an algorithm to avoid constantly writing out the same blocks.

However, in nutshell, there is an increased log on the logs and archive logs as well as their processes. Transactions go along fine with no differences. In addition, yes, data IS written to the data files while in begin backup mode and thus corrupting the data files (that is why full blocks are written out so they can be overlaid over the corrupted blocks in their entirety).

It is not recommended to do more than one tablespace in backup mode at the same time on a highly transactional system. Although this is highly system dependant.

"Do not criticize someone until you walked a mile in their shoes, that way when you criticize them, you are a mile a way and have their shoes."

Christopher R. Spence
Oracle DBA
Phone: (978) 322-5744
Fax: (707) 885-2275

Fuelspot
73 Princeton Street
North, Chelmsford 01863

-----Original Message-----
Sent: Tuesday, October 02, 2001 6:30 AM
To: Multiple recipients of list ORACLE-L

Hello All,

When you take begin back up of tablespace what exactly oracle does internally.

what happen the transcation in that period.

Please tell me .
Regards,
saroj.
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Author: Dash, Saroj (CAP,CEF)
INET: Saroj.Dash_at_gecapital.com

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Author: Christopher Spence
INET: cspence_at_FuelSpot.com

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