Re: VM-Ware Backup of VM safe?

> -----Ursprüngliche Nachricht-----
> Von: pgsql-general-owner(at)postgresql(dot)org [mailto:pgsql-general-
> owner(at)postgresql(dot)org] Im Auftrag von George Neuner
> Gesendet: Donnerstag, 21. September 2017 18:35
>
> I can't speak for all VM managers, but Vmware's standard static
snapshots
> *do* capture both the memory and power states of the machine. If a
snapshot
> is taken while a machine is running, restarting from that snapshot is
the same
> as if the machine woke up from suspension.

Thanks for clarification.

>
>
> >I may be wrong, but my understanding of a VSS writer is that all
> >transaction and log files are flushed to disk prior tot he snapshot.
>
> You understanding is correct - but I think you are maybe misapplying it
to this
> case. VSS operates in the *host*, not in the virtual machine. And VSS
is purely
> a Windows mechanism - it does not apply in Unix or Linux.

[...]

I am aware that VSS is purely Windows, and your comment about VSS aware
application is true. Backup programs / VM managers like Data Protection
Manager trigger these applications to put the files into a safe state
prior to the snapshot. As far as I am aware, MS SQL server provides this
mechanism while PostgreSQL does not. And for this reason, I would
certainly encourage using PostgreSQL's backup mechanisms for business
critical applications.

I just spoke with several admins who were not aware of these differences
between several databases.

Klaus