Toru SHIMOGAKI wrote:
Steve Atkins wrote:
- When we take a PITR base backup with hardware level snapshot operation
(not filesystem level) which a lot of storage vender provide, the
backup data
can be corrupted as Dan said. During recovery we can't even read it,
especially if meta-data was corrupted.
I can't see any explanation for how this could happen, other
than your hardware vendor is lying about snapshot ability.
All of the hardware vendors I asked always said:
"The hardware level snapshot has nothing to do with filesystem
condition and of course with what data has been written from operating
system chache to the hard disk platter. It just copies byte data on
storage to the other volume.
Right that has been my understanding as well.
Joshua D. Drake
So, if any data is written during taking snapshot, we can't assurance
data correctness *strictly* .
In Oracle, no table data is written between BEGIN BACKUP and END BACKUP,
and it is not a problem REDO is written..."
I'd like to know the correct information if the explanation has any
mistakes, or a good way to avoid the probrem.
I think there are users who want to migrate Oracle to PostgreSQL but
can't because of the problem as above.
Best regards,
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