Tom Lane wrote:
> Dan Gorman <dgorman@hi5.com> writes:
>> All of our databases are on NetApp storage and I have been looking
>> at SnapMirror (PITR RO copy ) and FlexClone (near instant RW volume
>> replica) for backing up our databases. The problem is because there
>> is no write-suspend or even a 'hot backup mode' for postgres it's
>> very plausible that the database has data in RAM that hasn't been
>> written and will corrupt the data.
> Alternatively, you can use a PITR base backup as suggested here:
> http://www.postgresql.org/docs/8.2/static/continuous-archiving.html
I think Dan's problem is important if we use PostgreSQL to a large size database:
- 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.
- If we don't use hardware level snapshot operation, it takes long time to take
a large backup data, and a lot of full-page-written WAL files are made.
So, I think users need a new feature not to write out heap pages during taking a
backup.
Any comments?
Best regards,
--
Toru SHIMOGAKI<shimogaki.toru@oss.ntt.co.jp>
NTT Open Source Software Center