Re: Parallelizing RMAN Backup

Hi Pat

I don't know where you got the information on the Rman will not parallel the backup without using the filesperset parameter. I only use the filesperset parameter when backing up archive files. It is the allocation of multiple channels that determinate if it is possible to do backup's in parallel.

Pat Howe wrote:

>>I am researching RMAN and I am trying to understand how to parallelize the
>>backup.
>>I have come across the following statement in various papers and in the 8i
>>Backup and Recovery Course Material :
>>
>>It is important to set FILESPERSET in the backup.
>>This will ensure that each allocated channel only processes the specified
>>number of files.
>>If you DO NOT specify FILESPERSET then the backup would only be undertaken
>>by "1 channel" and "all other allocated channels would sit idle".
>>
>>Yet in the "8.1.6 RMAN User's Guide and Reference" it contradicts this (pg
>>1-31) :
>>
>>The number of channels that you allocate affects the degree of parallelism
>>within the command.
>>RMAN internally handles parallelization. You only need to specify :
>> > 1 'allocate channel' command
>> The objects that you want to backup
>>Parallelism is exploited only within the context of a single command.
>>
>>So it does not mention that you HAVE TO specify the FILESPERSET statement.
>>
>>On digging further into the FILESPERSET statement the manual states (pg
>>1-36) :
>>The default value of this parm is calculated by RMAN as follows ;
>>RMAN takes the lower of the following 2 values ; 64 or
>>number-of-files/number-of-channels.
>>
>>Page 1-37 gives an example of using the Default FILESPERSET - and how RMAN
>>would parallelize the backup.
>>
>>Which is right ?
>>Do you have to specifically specify the FILESPERSET parm in the BACKUP
>>command for RMAN to parallelize the backup operation?
>>or
>>Can you leave it out of the BACKUP command and use the default value ?
>>
>>
>>Thanks in advance
>>
>>_________________________
>> Patrick J. Howe
>> Oracle DBA
>> Illuminet Inc. (Carrier Division of Verisign)
>> 4501 Intelco Loop SE
>> Olympia, WA 98507
>> Email : phowe_at_illuminet.com
>>
>>

-- 

/regards

Peter Gram

Phone : +45 2527 7107
Fax   : +45 4466 8856

Miracle A/S
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