Re: online vs. hot backup (was Re: Type of application - Mailing list pgsql-general

Quoting Ron Johnson <ron.l.johnson@cox.net>:

> On Fri, 2003-10-03 at 14:37, Network Administrator wrote:
> > Quoting Ron Johnson <ron.l.johnson@cox.net>:
> >
> > > On Fri, 2003-10-03 at 13:32, Network Administrator wrote:
> > > > Quoting Richard Huxton <dev@archonet.com>:
> > > >
> > > > > On Thursday 02 October 2003 19:55, Network Administrator wrote:
> > > > > > Quoting Richard Huxton <dev@archonet.com>:
> > > > > > >      [stuff deleted]
> > > [snip]
> > > > The other thing is that I suspect there might be some confusion as to
> the
> > > > difference between "hot backups" (dump of data does not require DB to
> be
> > > "down")
> > > > and "online backups" (dump of data is not needed because on the disk
> state
> > > of
> > > > the DB is current to some "recent" time).  To be perfectly honest,
> I've
> > > only had
> > >
> > > Huh?  This is the 1st time that I've ever seen mention that there
> > > is a distinction between "hot" and "on-line" backup.
> [snip garbage]
> >
> > I might be splitting hairs but I have had this conversation elsewhere.  It
> was
> > quiet awhile ago and I might not be using the right term  for "online".
> Using
> > my terminalogy though, doing a "hot backup" gives you data current to the
> time
> > of that backup.  Doing an "online backup" would give you data current to
> the
> > last time everthing was sync'd to disk.
>
> What the heck kind of DBMS doesn't make sure that the on-disk data
> is current?  In PG, that's "fsync=on", and turning it off is always
> strongly discouraged.
>
> --
> -----------------------------------------------------------------
> Ron Johnson, Jr. ron.l.johnson@cox.net
> Jefferson, LA USA
>
> "Whatever may be the moral ambiguities of the so-called demoratic
> nations and however serious may be their failure to conform
> perfectly to their democratic ideals, it is sheer moral
> perversity to equate the inconsistencies of a democratic
> civilization with the brutalities which modern tyrannical states
> practice."
> Reinhold Nieburhr, ca. 1940
>
>
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Well, like I said this was years ago at this point so you really can't compare
now to then.  I lived through that so I don't equate the terms.  As for
"strongly discouraged", the docs don't read that way.  The implications of both
fsync being "true" or "false".  Either way, its academic now.


--
Keith C. Perry
Director of Networks & Applications
VCSN, Inc.
http://vcsn.com

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