Re: Oracle Backup and Recovery Handbook

In article <4q9q29$htq_at_news.inforamp.net> lokp_at_tdbank.ca writes:
>
>I was going through those case studies listed in the last chapter of
>the 'Oracle Backup and Recovery Handbook' and noticed that the author
>likes to do several log switches in a row before simulate each failure
>case. Does any one know why more than one log switch is required??

I would guess that he wants to make sure that all outstanding log writes are forced to all the redo logs. The redo logs are possibly going to be a bottleneck for I/O, and if you are simulating failures, you want to force the logwriter to flush everything to disk to get consistent results from the testing. The log files are cycled through, so repeated log switches will put them all in the same state from the point of view of the hardware and OS. Remember, there are buffers in the Oracle processes, in the OS kernel that controls the I/O devices, and possibly in the devices themselves.

jg

>
>Thanks...
>
>Peggy Lok
>
>

-- 
Joel Garry               joelga_at_rossinc.com               Compuserve 70661,1534
These are my opinions, not necessarily those of Ross Systems, Inc.   <> <>
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panic: ifree: freeing free inodes...                                   O