1. Backup of RMAN catalog: Using OS backup or another RMAN catalog?
Read that if using OS Backup, BMR not possible in case of loss of catalog!
2. Channels : Auto or Manual allocation - which is best - is it hardware/MML&MMS vendor dependent?
3. Any BP's on Rman..links etc. ?
1. Either way is fine. Most shops prefer OS or regular hot backups. What's BMR?
2. A channel represents a stream of data to a device type. So yes, you gotta point this appropriately per the MML. Auto / Manual - your choice. Whatever works for you. Might as well set auto, and overide when required by manually allocating channels within your script.
3. BP - Blood pressure? Here's a link to the RMAN user guide. It should address most of your RMAN questions.
AFAIK - "as far as i know". It indicates a certain level of uncertainity.
Anyway - I've not performed RMAN BMR. But look at the below RMAN userguide and procedures for performing BMR. There is nothing there which explicitly or implicitly indicates that one absolutely requires a catalog. It's just a "blockrecover..datafile..restore" command. I don't see why this would *require* a catalog.
Nothing in the docs. - can only surmise that since it's in a format that only RMAN can read/write, an OS backup may not be of use.
Have sent an e-mail to the author's website - will post if an enlightening reply is received!!
Can you quote the lines from the book? Am guessing all that the author would've said is - you can't perform BMR on the target with an OS backup (of the target); but only with an RMAN backup (of the target). That is actually pretty obvious.
BMR not possible in case of loss of catalog!
like you said.
All, I'm saying is you should be able to use the controlfile of the target to perform BMR even if you lose the catalog.
OS/Traditional backups can't be used for BMR, because of the architecture (RMAN rereads fractured blocks without need for placing files in backup mode). For one, there is no interface with a traditional/OS backup to say "hey, I need block# to be replaced on file#", then read all my backed up archivelogs, look if this block has changed, and if it did - replace it (just that one corrupted block). RMAN has this capability because it tracks the information - it tracks used/changed blocks.
Well the controlfile could be used unless the corrupt blocks info. is aged out & overwritten - do not remember if this is a permanent or circularly reused record in the controlfile - would expect it to be permanent - guess will have to pore deeper through the docs. - but will be obliged if you could clarify this. Will post the exact lines from the book when I can - the developer who brought this to my attention has it & have'nt been able to touch base with him yet !!