[Info-vax] OpenVMS x64 Atom project

[Arne Vajhøj]

On 6/6/2021 12:45 PM, Jan-Erik Söderholm wrote:
> Den 2021-06-06 kl. 17:36, skrev Arne Vajhøj:
>> But the rule is still that either the database will be unavailable
>> for significant time or one need a snapshot capability where updates
>> can be done but the backup sees the snapshot data at the time of the
>> snapshot.
>>
>> Storage or file system or database - the basic problem is the same.
> 
> Yes. Rdb solves that using a "quiet point". As can be seen from the log
> file above, that took 2 sec (freezing and waiting for active transactions
> to finish). EFter that 2 sec delay, all update activity are back to normal
> while the backup continues to run. The data backed up is the data that
> was there at the point in time of the "quiet point lock release".
> 
> And any "snapshot" data is only saved to the "snapshot file" in the case
> that some process request to update it. If not, there is no reason to
> copy any data, of course. 99% of the database will be untouched during
> the backup and thus not copied to the snapshot file.
> 
> So most of the data backed up is "real" data, not snapshot data.

Yes.

I think that is common as well.

I believe that SpiraLog would have worked similarly - if anyone
still remembers that.

Arne